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April 15, 2021

https://www.sciencedaily.com/releases/2021/04/210415114202.htm

Impacts of coronavirus lockdowns: New study collects data on pollutants in the atmosphere

One consequence of the coronavirus pandemic has been global restrictions on mobility. This, in turn, has had an effect on pollution levels in the atmosphere. Researchers from across the world are using this unique opportunity to take measurements, collect data, and publish studies. An international team led by Forschungszentrum Jülich's Institute of Climate and Energy Research -- Troposphere has now published a comprehensive review providing an overview of results up to September 2020. The study also has its own dedicated website, where additional measurement data can be added to supplement and refine existing research results. At the same time, this collection of data allows scientifically substantiated predictions to be made about the pollution levels of future mobility scenarios.

The meta-analysis was coordinated by Prof. Astrid Kiendler-Scharr, director at Jülich's Institute of Climate and Energy Research -- Troposphere. The analysis covers the measurement data of around 200 studies from the first seven months following the onset of the pandemic. It focuses on the following air pollutants: nitrogen dioxide, particulate matter, ozone, ammonia, sulfur dioxide, black carbon, volatile organic compounds (VOCs), and carbon monoxide. A third of the studies take into account the prevailing meteorological situation when calculating the influence of lockdowns on the air composition. The Government Stringency Index (SI) -- summarizing the severity of local shutdown measures in a number that can be compared at international level -- acted as a reference value.A key finding of the analysis is that lockdowns, which have the sole aim of slowing down the infection rate, are also reducing the global pollution of the atmosphere with nitrogen dioxide and particulate matter -- the higher the SI, the greater this impact. However, this only applies to pollutants that primarily have an anthropogenic origin, i.e. are directly emitted by humans, especially in the field of mobility. In contrast, ozone levels increased. This increase was a result of atmospheric chemical processes caused by reduced nitrogen oxide levels in the air.The study also highlights current gaps in the data collection and the need for further research. The authors are therefore of the opinion that the period of analysis should be extended to cover the entire year of 2020. The scientists place a particular emphasis on hydrocarbons, which have so far only been examined sporadically in studies, and on extended analyses looking at the impact of emission changes on the climate.An important addition to the meta-analysis is a database that can be accessed via a website (COVID-19 Air Quality Data Collection -- The website also invites scientists to present data from their new studies and to thus become part of the reference system. It therefore acts as a "living version," with the presentation of collected results being constantly refined. Similarly, there are plans to further develop the data collection to include measurement results and the analysis of other pollutants that are not part of the current canon, for example hydrocarbons.The important data could also form the basis for better assessments of the impacts on atmospheric chemistry in future scenarios. This includes a considerable, long-term reduction in pollution levels for a comprehensive transition to electromobility.

Ozone Holes

April 5, 2021

https://www.sciencedaily.com/releases/2021/04/210405123308.htm

Ozone pollution harms maize crops, study finds

Although stratospheric ozone protects us by filtering out the sun's ultraviolet radiation, tropospheric ozone is a harmful pollutant. A new study has shown that ozone in the lower layers of the atmosphere decreases crop yields in maize and changes the types of chemicals that are found inside the leaves.

Ozone is formed when nitrous oxide, released from industries and tail pipes of cars, is broken down by sunlight and chemically reacts to form ozone. Researchers at the University of Illinois Urbana-Champaign have been studying the effects of ozone pollution on crops for over 20 years at a unique facility where crops can be grown under real-world farm field conditions but with increased concentrations of ozone pollution."Ozone pollution is higher in the northern hemisphere, and peaks in the warmer, summer months. High concentrations of ozone pollution overlap temporally and spatially with crop growth, so it is important to study how the high ozone concentrations affect crop yields," said Jessica Wedow, a former PhD student in the Ainsworth lab.The researchers looked at three types of maize: two inbred lines B73 and Mo17, and the hybrid cross B73 × Mo17. Surprisingly, they found that chronic ozone stress caused a 25% decrease in yield in the hybrid crops while the inbred plants remained unaffected. The hybrid plants also aged faster than the inbred crops.To understand why B73 × Mo17 was affected, the researchers measured the chemical composition of the leaves. "The inbred plants did not respond to ozone. On the other hand, the hybrid plants produced more ??tocopherol and phytosterols, which help quench reactive oxygen molecules and stabilize the chloroplast membranes," Wedow said. These results suggest that the since the hybrid maize is more sensitive to ozone exposure, they may be producing more chemicals that deal with the consequences of chronic ozone stress."This study provides clues to improve maize tolerance to ozone pollution," said Lisa Ainsworth (GEGC), the Research Leader of the USDA ARS Global Change and Photosynthesis Research Unit. The group is currently studying whether these responses are consistent across other important grasses, including those used for bioenergy.

Ozone Holes

December 2, 2020

https://www.sciencedaily.com/releases/2020/12/201202114540.htm

Ozone breaks down THC deposited on surfaces from thirdhand cannabis smoke

Second- and thirdhand tobacco smoke have received lots of attention, but much less is known about the compounds deposited on surfaces from cannabis smoke. Now, researchers reporting in ACS'

Smoking emits reactive chemicals that remain in the air (so-called secondhand smoke) or deposit onto surfaces, including walls, windows, clothing and upholstery (thirdhand smoke). Unlike the secondhand variety, thirdhand smoke lingers long after a person stops smoking. Nicotine is semi-volatile and reacts with other chemicals on surfaces, producing new compounds that, if volatile, can also become airborne. Because cannabis smoke is chemically distinct from tobacco smoke, Aaron Wylie and Jonathan Abbatt wanted to characterize the compounds formed when THC, by itself or in cannabis smoke, on surfaces reacts with ozone in the air.The researchers coated glass and cotton cloth, to simulate windows and clothing, with a THC solution. Then, they exposed the surfaces to concentrations of ozone that could exist in indoor air. In their analysis, they found that over time, the amount of THC on glass and cotton decreased, while the quantities of three THC oxidation products increased. In other experiments, the team used a smoking machine to deposit cannabis smoke onto cotton. Upon exposure to ozone, the same three compounds formed at roughly the same rate as observed for the THC-coated cloth. Because of the low volatility of THC and its oxidation products, the compounds are unlikely to be emitted to the air where they could be inhaled in as large amounts as nicotine, the researchers say. They say that somebody could still be exposed to THC and its derivatives, whose health effects are unknown, if they, for example, lick their fingers after touching a surface contaminated by cannabis smoke.The authors acknowledge funding from the Chemistry of Indoor Environments program at the Alfred P. Sloan Foundation.

Ozone Holes

November 23, 2020

https://www.sciencedaily.com/releases/2020/11/201123120730.htm

Shift in atmospheric rivers could affect Antarctic sea ice, glaciers

Weather systems responsible for transporting moisture from the tropics to temperate regions in the Southern Hemisphere have been gradually shifting toward the South Pole for the past 40 years, a trend which could lead to increased rates of ice melt in Antarctica, according to new research.

Atmospheric rivers are long, narrow jets of air that carry huge amounts of water vapor from the tropics to Earth's continents and polar regions. The new study finds atmospheric rivers in the Southern Hemisphere are shifting due in part to ozone depletion, greenhouse gas emissions and natural variations in sea surface temperature.This shift of atmospheric rivers may affect moisture and heat transported into Antarctica, said Weiming Ma, an atmospheric scientist at UCLA and lead author of the new study published in the AGU journal "The most important implication of our finding is that due to this shift, more atmospheric rivers are expected to make landfall over Antarctica, which will have effects on the surrounding sea ice and glaciers on the continent," Ma said.Atmospheric rivers form when warm, turbulent air from the tropics encounter cold fronts in mid-latitude regions. The narrow band between these two competing air masses grows thick with condensed water vapor as temperatures drop in the region of saturated air.Sometimes measuring thousands of kilometers in length, these cloud systems can contribute up to 60% of the annual precipitation in some regions, such as California, Chile and western Europe.In the past, scientists have used simulations to predict the future occurrence of atmospheric rivers over western Europe, showing that these weather patterns are likely to become more common under a warming climate. However, since their direction and movement are determined in large part by Earth's jet streams, and as the westerly jet is expected to shift toward the North Pole in future climate models, researchers predict that atmospheric rivers will likely move poleward as well.But the new study found atmospheric rivers in the Southern Hemisphere have already been following this trend, steadily creeping toward the South Pole for at least the last four decades. Using simulations based on multiple models and datasets spanning back to 1979, the researchers looked for broad trends and potential mechanisms that might explain observed patterns.According to modeling results from the new study, at least part of the observed trend can be explained by increases in greenhouse gas emissions and ozone depletion over Antarctica and their corresponding effect on temperature gradients between the equator and South Pole; however, the shift also appears to be driven by natural, long-term changes in sea surface temperatures."We found evidence for cooling over the equatorial Pacific and the Southern Ocean, which is caused by a pattern called the inter-decadal Pacific Oscillation," said Ma. "This is a natural pattern that takes place over multiple decades and one that isn't driven by human activity."These cooler patterns in sea surface temperature pull the westerly jet stream further south, pushing atmospheric rivers along with them. It's unclear exactly how this might affect rain and snowfall patterns over South America, but it seems likely that portions of Antarctica will experience increased rates of ice melt as a result, according to the researchers."Global sea level change depends critically on the fate of the Antarctic ice sheet, and that ice is impacted by how many atmospheric rivers hit Antarctica and how strong they are," said Marty Ralph, the director for the Center for Western Weather and Water Extremes at the Scripps Institution of Oceanography, who was not involved in the new study.While atmospheric rivers over East Antarctica have been associated with increased snowfall accumulation in some years, they seem to have the opposite effect on the other side of the continent. According to research published in 2019 that used a similar dataset, an average of only 12 atmospheric rivers a year make their way across the western portion of Antarctica, yet they contribute up to 40% of the summer ice melt in some areas and appear to be responsible for the majority of ice melt in winter and in high-elevation glaciers.Large ice melts in West Antarctica are still fairly rare, occurring only a few times each decade. However, scientists warn that increasing temperatures due to global climate warming and the shifting occurrence of atmospheric rivers in the southern hemisphere will likely cause the frequency and severity of those melting events to increase in the near future.

Ozone Holes

September 24, 2020

https://www.sciencedaily.com/releases/2020/09/200924082709.htm

Climate pledges 'like tackling COVID-19 without social distancing'

Current global pledges to tackle climate change are the equivalent of declaring a pandemic without a plan for social distancing, researchers say.

In the Paris Agreement, nations agreed to limit global warming to "well below 2°C."But University of Exeter scientists say governments are engaged in "climate hypocrisy" by publicly supporting the agreement while subsidising the fossil fuel industry, destroying forests and pursuing other harmful policies.Writing in the journal The call comes as world leaders including UK Prime Minister Boris Johnson discuss climate action and a "sustainable recovery" from the pandemic at the UN General Assembly."Restoring the ozone layer and minimising the COVID-19 pandemic both required governments to enact specific legislation to address the precise causes of these problems," said Professor Mark Baldwin, of Exeter's Global Systems Institute (GSI)."By contrast, Paris Agreement commitments are the equivalent of intending to restore the ozone layer without a plan for eliminating ozone-depleting substances, or intending to end the COVID-19 pandemic without a plan for social distancing to reduce the spread of the virus."We know the climate crisis is caused mainly by fossil fuels."Current climate and energy policies are therefore nonsensical because they condemn greenhouse gas emissions by individuals while promoting fossil fuel production."Today we have governments publicly supporting the Paris Agreement, but simultaneously opening new coal mines, destroying forests, supporting fracking, subsidising the fossil fuel industry and supporting fossil fuel projects in the developing world."Professor Tim Lenton, director of the GSI, said: "The fundamental reason we are not solving the climate crisis is not a lack of green energy solutions -- it is that many governments continue energy strategies that prioritise fossil fuels."These entrenched energy policies subsidise the discovery, extraction, transport and sale of fossil fuels, with the aim of ensuring a cheap, plentiful, steady supply of fossil energy into the future."Some governments are introducing policies to reduce demand for fossil fuels and shift to green energy sources, but these policies are not enough."Green energy is not yet replacing fossil fuels -- it is merely augmenting it. Energy from both fossil fuels and green sources is increasing."Individual behaviour choices -- such as diets and modes of travel -- are important, but more fundamental is to replace the supply of fossil fuels with green energy."The researchers call for a "comprehensive global plan" to solve the climate crisis.They make seven recommendations:Professor Baldwin added: "To bring about real change, we must address complex issues involving politics, fake news, human behaviour, government subsidies, taxes, international trade agreements, human rights, lobbying by the fossil fuel industry, and disinformation campaigns."

Ozone Holes

September 21, 2020

https://www.sciencedaily.com/releases/2020/09/200921130640.htm

Unexpected wildfire emission impacts air quality worldwide

In lab studies of wildfire, nitrous acid seems like a minor actor, often underrepresented in atmospheric models. But in the real-world atmosphere, during wildfires, the chemical plays a leading role -- spiking to levels significantly higher than scientists expected, driving increased ozone pollution and harming air quality, according to a new study led by the University of Colorado Boulder and the Belgian Institute for Space Aeronomy.

"We found nitrous acid levels in wildfire plumes worldwide are two to four times higher than expected," said Rainer Volkamer, CIRES Fellow, professor of chemistry at CU Boulder and co-lead author on the Nitrous acid in wildfire smoke is accelerating the formation of an oxidant, the hydroxyl radical or OH. Unexpectedly, nitrous acid was responsible for around 60 percent of OH production in the smoke plumes worldwide, the team estimated -- it is by far the main precursor of OH in fresh fire plumes. The hydroxyl radical, then, can degrade greenhouse gases, and it can also accelerate the chemical production of ozone pollution -- by as much as 7 parts per billion in some places. That's enough to push ozone levels over regulated levels (eg, 70 ppb in the United States)."Fire size and burn conditions in the real world show higher nitrous acid than can currently be explained based on laboratory data, and this added nitrous acid drives faster chemistry to form ozone, oxidants and modifies aerosols in wildfire smoke," Volkamer said.Nitrous acid, while abundant after wildfire, degrades quickly in sunlight, and is thus exceedingly difficult to study globally. So the CU Boulder team worked with European colleagues to combine two sets of data: 1) global measurements from a satellite instrument TROPOMI observed nitrous acid in wildfire plumes around the world, and 2) custom instruments flown on aircraft during a 2018 wildfire study in the Pacific Northwest during the BB-FLUX campaign. Remarkably, the team was able to compare near-simultaneous measurements made within minutes by the satellite looking down on a plume, and the aircraft-based instrument looking up into the same plume from below."Kudos to the pilots and the entire team for dealing actively with this fundamental sampling challenge," Volkamer said. "Simultaneous measurements conducted at different temporal and spatial scales helped us to understand and use what are the first global measurements of nitrous acid by our Belgium colleagues." With the new comparison in hand, Volkamer and his colleagues -- including Nicolas Theys, the study's lead author from BIRA -- could then scrutinize satellite data from a large number of wildfires in all major ecosystems across the planet to assess nitrous acid emissions.The chemical is consistently higher than expected everywhere, but levels differ depending on the landscape. "Nitrous acid emissions relative to other gases involved in ozone formation varied by ecosystem, with the lowest in savannas and grasslands and highest in extratropical evergreen forests," said Kyle Zarzana, chemistry postdoctoral scientist at CU Boulder who led instrument deployment for the aircraft measurements, and coauthor on the new paper."Wildfire smoke contains many trace gases and aerosols that adversely affect visibility and public health over large distances, as we are recently witnessing from fires raging in the Western United States that affect air quality on the East Coast," said Volkamer. "Our findings reveal a chemically very active ingredient of this smoke, and help us to better keep track as photochemistry rapidly modifies emissions downwind."

Ozone Holes

September 8, 2020

https://www.sciencedaily.com/releases/2020/09/200908131032.htm

Detecting soil-surface ozone early can help prevent damage to grapes and apples

Farmers and fruit growers are reporting that climate change is leading to increased ozone concentrations on the soil surface in their fields and orchards -- an exposure that can cause irreversible plant damage, reduce crop yields and threaten the food supply, say materials chemists led by Trisha Andrew at the University of Massachusetts Amherst.

Writing in They write, "We selected grapes (Vitis vinifera L.) as our model plant because the fruit yield and fruit quality of grapevines decrease significantly upon exposure to ground level ozone, leading to significant economic losses." Ground-level ozone can be produced by the interaction between the nitrates in fertilizer and the sun, for example.UMass Amherst viniculturist Elsa Petit, who advised the chemistry team, says the sensor tattoo could be especially useful to the grape industry. "With climate change, ozone will increase and this new sensor might be extremely useful to help farmers act before the damage is recognizable by eye," she says. Ground-level ozone can be mitigated by early detection and treating the soil surface with charcoal or zeolite powders.As Andrew explains, her lab, funded by the National Science Foundation, adapted the electrode vapor-deposition method they had developed earlier to coat fabrics for medical sensing devices for a new use -- on living plants. The conducting polymer film, poly(3,4-ethylenedioxytiophene), PEDOT, is just 1 micron thick so it lets sunlight in and does not hurt leaves. Non-metal, carbon-based polymers that act as conducting electrodes are increasingly used in soft materials design since they were invented in the 1970s, she adds."Ours acts like a temporary tattoo on a human," Andrew says. "It doesn't wash away and the polymer's electrical properties don't degrade, even over a long time. We have some tattooed plants in a greenhouse on campus and a year later they are still growing fine, putting out roots and leaves as normal."To test for early ozone damage, she and colleagues use a hand-held impedance spectrometer adapted from human medical practice. When it touches the electrode tattoo, a read-out reports the electrical resistance vs frequency relationship. This voltage value changes in the presence of various factors, including oxidative damage from ozone.Andrew says, "You get a wave-form image; a software program fits the wave so we can extract certain tissue parameters. We can recognize patterns for different kinds of damage. It's consistent and remarkably accurate. If you use it on the same plant over a year, as long as the plant is healthy the signal doesn't really change over that time.""The problem scientifically is that visual ozone damage looks exactly the same as if you watered the plant too little or it got too much sun. This project became intellectually interesting to us when we looked at the ozone signature of our read-outs and it was very different from drought or UV damage. Ozone produces a unique change in the high-frequency electrical impedance and phase signals of leaves."The scientists hope their invention could be used by farmers and fruit growers who could place a few "reporter plants" among crops to periodically monitor soil ozone levels. "It gives you a picture of what is going on in your soil," Andrew suggests. "You can be alerted if the fertilizer level is wrong, for example. This can happen, especially with food crops that need a lot of sun and fertilizer to produce, like melons, grapes and orchard fruits. Some plants are very sensitive to it."

Ozone Holes

September 4, 2020

https://www.sciencedaily.com/releases/2020/09/200904101806.htm

Pollination: Air pollution renders flower odors unattractive to moths

A team of researchers from the Max Planck Institute for Chemical Ecology in Jena, Germany, and the University of Virginia, USA, has studied the impact of high ozone air pollution on the chemical communication between flowers and pollinators. They showed that tobacco hawkmoths lost attraction to the scent of their preferred flowers when that scent had been altered by ozone. This oxidizing pollutant thus disturbs the interaction between a plant and its pollinator, a relationship that has evolved over millions of years. However, when given the chance, hawkmoths quickly learn that an unpleasantly polluted scent may lead to nutritious nectar.

Pollination is a critical ecosystem service, one that is performed mainly by insects. Flowers attract insects using floral scents, which are chemical signals that the pollinators can have an innate preference for. This preference is the result of the co-evolutionary relationship between flowers and their pollinators that has evolved over millions of years.For about 20 years, the term "Anthropocene" has been used in the scientific community to refer to the geological epoch in which humans are responsible for many changes in biological and atmospheric processes. However, until recently, little has been known about the effects of anthropogenic climate change and atmospheric pollution on natural environmental odors that drive chemical communication between organisms.A team of researchers from the Max Planck Institute for Chemical Ecology and the University of Virginia has investigated whether human-driven ozone pollution in the air influences the attraction of a pollinating moth to the scent of one of their favorite flowers. Ozone is an oxidant, a highly reactive chemical and pollutant known to cause respiratory diseases in humans. Now, ozone is also thought to change the floral scents that flowers emit to attract their pollinators.For their experiments, the scientists used the tobacco hawkmoth Manduca sexta. "The hawkmoth Manduca sexta is the perfect model for our study. Although it is highly attracted by flower odors, it also uses its visual system to locate flowers. Flowers that usually attract hawkmoth often share specific compounds in their blend and are visually very conspicuous due to their bright white color," says study leader Markus Knaden, who heads a research group in the Department of Evolutionary Neuroethology at the Max Planck Institute.The research team first determined the exact compositions of the flower odors -- with and without increased ozone content -- and the respective concentrations of individual odor components using gas chromatography. For the ozone-altered odors, the researchers used ozone concentrations that can be measured on hot days in the natural habitat of tobacco hawkmoths. They tested the responses of the moths in behavioral assays in a wind tunnel, allowing the insect to investigate both the original floral odor and to the ozone-altered floral odor."We were surprised, even shocked, that the innate attraction to the odor of tobacco flowers was completely lost in the presence of increased ozone levels," said Knaden, describing what was observed during the experiments.The question remained whether ozone in the air would spoil the appetite of hungry and foraging tobacco hawkmoths, or whether it would prevent insects from finding their food source. Would insects be able to figure out that even polluted flower odors can offer rewards? To answer this question, researchers tested whether tobacco hawkmoths could learn to accept an initially unattractive scent as a food cue if they smelled it while simultaneously being offered a sugar solution reward. The researchers assessed several different ways in which the moth could learn to recognize flowers based on the ozone-altered floral scent. This was critical to relating these experiments to real-world learning. In the real world, a floral scent only becomes ozone-altered as it moves downwind of the flower and mixes with ozone. To see if moths could learn ozone-altered floral scents even when they are decoupled from the sugar reward at the flower, the researchers developed an experiment where the moth had to follow the ozone-altered odor to the flower, but were presented with the original scent at the flower containing the sugar reward."While we anticipated that Manduca sexta could learn new floral scents and hoped that they would be able to learn the polluted floral scent of their host flower, we were amazed to see that Manduca sexta could learn the polluted floral blend in a number of different ways, including learning a polluted scent that was decoupled from a sugar reward. This type of learning, which we were surprised to find in Manduca sexta, could be very important in insects' ability to use learning to cope with their rapidly changing environments," says first author Brynn Cook from the University of Virginia. What is especially noteworthy and pertinent about this kind of responsiveness to a changing environment is that it occurs in real time and not over evolutionary timescales.Although the study shows that tobacco hawkmoths can learn to rely on ozone-altered and initially unattractive plumes to recognize their flowers, air pollution still poses a serious risk to pollination and pollinators. "Learning may be key to insects recognizing their host plants in polluted environments, but one of the major questions remaining from our study is whether pollinators will be able to find their flowers in the first place. Without initially recognizing smells, will pollinators only have visual cues to help them locate host flowers in order to learn the pollution-altered floral scent? Another important aspect to consider is that other pollinators may not have the same facility to learn new smells that Manduca sexta has. Specialist pollinators, for instance, may not have that flexibility in learning. Our study is just a starting point. Field studies are going to be critical to understanding which flowers and insects are most affected by which pollutants, and likely why," says Cook.Air pollution and climate change have far-reaching consequences for our ecosystem; by no means have all of these been studied and understood. For example, we still know little about the impact of atmospheric changes on the chemical communication between plants and insects. Not only are plant odors altered, but also the sex pheromone female insects use to attract males. Atmospheric changes have the potential to cause alterations in pheromones that could lead to mating failure. Insect mortality has risen dramatically in recent years, and researchers worldwide are searching for the causes. Since 2020, the Max Planck Center next Generation Insect Chemical Ecology, a cooperation between the Max Planck Society and two Swedish universities in which the Max Planck Institute for Chemical Ecology and the co-authors of the study, Bill Hansson and Markus Knaden, play a major role, has been dedicated to this field of research.

Ozone Holes

August 27, 2020

https://www.sciencedaily.com/releases/2020/08/200827105911.htm

Forest emissions: A chiral surprise in the rainforest

Forests such as the Amazon rainforest emit huge amounts of biogenic volatile organic compounds (BVOC) into the atmosphere. These compounds impact the physical and chemical properties of the atmosphere and also our climate. The molecules react rapidly with ambient OH radicals and ozone, thereby influencing the oxidation capacity of the atmosphere for pollutants such as carbon monoxide and greenhouse gases such as methane. Furthermore, BVOC are precursors to secondary organic aerosols, which affect the Earth's radiative budget. Many BVOCs such as a-pinene are chiral. This means that they exist in two non-superimposable mirror image forms just like our left and right hands. Scientists speak of enantiomers, or plus and minus forms. However, all physical properties such as their boiling point, mass and their reaction rate with atmospheric oxidizing agents like OH and ozone are identical.

Despite the chemical similarity of these chiral pairs, insects and plants can distinguish enantiomeric forms of pheromones and phytochemicals, although little attention has been paid to the mixing ratio of the two separated forms in forests. Previous measurements reported minus α-pinene to be the dominant chiral molecule of the tropical forest. Scientists from the Max Planck Institute for Chemistry, the Johannes Gutenberg-University Mainz and from Brazil have now made a surprising discovery: from the 325-meter-high measuring tower in the Amazon rainforest, they were able to show that the ratio of the α-pinene enantiomers varies in the vertical by a factor of ten. The team around the Max Planck researcher Nora Zannoni was also able to demonstrate that the concentrations are altitude-dependent and vary with the time of day and in both wet and dry seasons.While plus-α-pinene dominates at 40 meters anytime and at 80 meters during the night, the minus form predominates at 80 meters during the day and at all other higher heights anytime. The team also observed that the minus α-pinene concentration depends on temperature at 80 meters while plus α-pinene does not. "The photosynthetic activity of the vegetation depends on temperature and stomatal opening. It thus drives the emissions of minus α-pinene, demonstrating that leaves are the main source of emission of this isomer, and that the two isomers are released from leaves through different pathways," says Zannoni, who is first author of a study recently published in the science magazine During the dry season, the chiral ratio of the two forms reverses at 80 meters. "This indicates a strong, uncharacterized source of plus α-pinene in the canopy," says Jonathan Williams, group leader at the institute in Mainz and last author of the study. Since the researchers couldrule out atmospheric sinks such as the chiral-selective degradation of pinene by OH radicals and ozone or deposition onto aerosols as well as the influence of wind direction and sunlight, they instead suspect that insect stresses such as herbivores feeding and termites emissions are responsible for the plus α-pinene higher values. In order to test a possible impact of insects the researchers conducted additional measurements above termite nests which confirmed that such emissions can overturn the ambient chiral ratio of α-pinene. As termite populations are expected to increase significantly in the future with continued deforestation and climate warming, their influence needs to be considered in forest emission models and forest signaling."We also know that plants can release large amounts of plus α-pinene when injured or eaten," Williams adds. This is supported by measurements of volatile compounds associated with leaf wounding that even revealed when the herbivores were most active. The atmospheric chemists Zannoni and Williams conclude that they need to rethink how canopy emissions of volatile organic compounds are simulated, and take the whole ecosystem into account.The research was co-financed by the H2020 project "ULTRACHIRAL" of the European Union.

Ozone Holes

August 26, 2020

https://www.sciencedaily.com/releases/2020/08/200826083036.htm

Experts reveal major holes in international ozone treaty

A new paper, co-authored by a University of Sussex scientist, has revealed major holes in an international treaty designed to help repair the ozone layer, putting human health at risk and affecting climate.

Evidence amassed by scientists in the 1970s and 1980s showed that the depletion of the ozone layer in the stratosphere was one of the first truly global threats to humanity.Chemicals produced through economic activity were slowly drifting to the upper atmosphere where they were destroying the ozone layer, which plays an indispensable role in protecting humanity and ecosystems by absorbing harmful ultraviolet radiation from the sun.In 1987, countries signed up to a treaty to take reparative action, known as the 'Montreal Protocol on Substances that Deplete the Ozone Layer, which was eventually ratified by all 197 UN member states.'But in a paper published today in Professor Joseph Alcamo, Director of the Sussex Sustainability Research Programme and former Chief Scientist at UNEP, said: "The Montreal Protocol and its amendments have no doubt been an effective worldwide effort to control the toughest substances depleting the ozone. But our paper shows that the treaty has developed too many gaps to fully repair the ozone layer. It's time to plug the holes in the ozone hole treaty."Professor Alcamo, along with lead author Professor Susan Solomon of Massachusetts Institute of Technology (MIT) and co-author Professor A. R. Ravishankara of Colorado State University, have identified several 'gaps' which consist of ozone depleting substances not covered in the treaty.These include:The authors have called for a range of solutions to plug the gaps including:The ozone layer absorbs harmful ultraviolet radiation from the sun but this protective layer is slowly destroyed by industrial gases that slowly drift up from the earth's surface including CFCs (chlorofluorocarbons) contained in refrigerants, foaming agents and, earlier, propellants in aerosol sprays.Discovery of the 'ozone hole' above high latitudes in the 1980s provided final evidence of the importance of ozone depletion.By 1985, countries had signed the Vienna Convention, which pledged to reduce CFCs and other ozone-depleting substances. Two years later, they signed the Montreal Protocol that laid out a plan of action.During his time as the first Chief Scientist of UNEP, which hosts the Secretariat of the Montreal Protocol, Professor Alcamo coordinated groups of scientists in producing policy-oriented reports that addressed emerging ozone depletion issues.UNEP reports that 98% of the chemicals targeted for removal in the Montreal Protocol had been phased out by 2009, avoiding hundreds of millions of cases of skin cancer and tens of millions of cases of cataracts. However, this new paper shows that some important sources were not targeted by the Protocol -- and urgently need to be now.Professor Alcamo said: "Since most ozone-depleting gases and their current substitutes are also potent greenhouse gases, it's time to use the Montreal Protocol to draw down these gases even faster to help avoid dangerous global warming."We won't be able to reach the global Sustainable Development Goals by 2030 without closing the gaps in the ozone treaty. It's hard to imagine, for example, how the global health and climate goals could be reached without drastically drawing down all ozone-depleting gases and their substitutes. If we fail, humanity will have to face a higher risk of skin cancers and more rapid climate change."

Ozone Holes

August 21, 2020

https://www.sciencedaily.com/releases/2020/08/200821141311.htm

Ozone across northern hemisphere increased over past 20 years

In a first-ever study using ozone data collected by commercial aircraft, researchers from the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder found that levels of the pollutant in the lowest part of Earth's atmosphere have increased across the Northern Hemisphere over the past 20 years. That's even as tighter controls on emissions of ozone precursors have lowered ground-level ozone in some places, including North America and Europe.

Tropospheric ozone -- ozone between Earth's surface and 12 to 15 kilometers above Earth -- is a greenhouse gas and air pollutant that, at high levels, can harm people's lungs and damage plants.In a study published today in the journal Gaudel and her co-authors, CIRES scientists in NOAA and international colleagues, also found the most striking increases in areas where ozone levels were once lowest: Malaysia/Indonesia, Southeast Asia and India, for example. Those regions had very low ozone values between 1994-2004, and very high levels in recent years, between 2011-2016.Previous studies could not draw firm conclusions on Northern Hemisphere ozone trends, according to Gaudel, because there are too few long-term monitoring locations and because new satellites with near-global coverage have provided conflicting results on ozone trends.So the researchers turned to aircraft data from Europe's In-Service Aircraft for the Global Observing System (IAGOS) program. "Since 1994, IAGOS has measured ozone worldwide using the same instrument on every plane, giving us consistent measurements over time and space from Earth's surface to the upper troposphere," Gaudel said. Between 1994 and 2016, commercial aircraft captured 34,600 ozone profiles, or about four profiles each day.Gaudel and her colleagues used these measurements to calculate changes in tropospheric ozone from the mid-1990s to 2016 above 11 regions in the Northern Hemisphere. They found an overall increase in ozone in all regions where they looked, including four in the mid-latitudes, two in the subtropics, two in the tropics and three equatorial regions. On average, median ozone values had increased by 5% per decade.In the so-called "lower troposphere," which is closer to Earth's surface, ozone has decreased above some mid-latitude regions, including Europe and the United States, where ozone precursor emissions have decreased. The researchers found those reductions were offset by increases higher in the troposphere -- with the net result being an overall ozone increase from the surface to 12 km.To understand what was causing the observed ozone changes, the researchers looked at the emissions inventories of one of the main ozone precursors -- nitrogen oxides (NOx) -- used as input for the global chemistry transport model MERRA-2 GMI, which reproduces accurately the IAGOS measurements. The model showed that increased anthropogenic emissions in the tropics were likely driving the observed increase of ozone in the Northern Hemisphere.Next, Gaudel wants to take a closer look at ozone in the tropics. Africa may be emerging as a global hotspot for air pollution precursors, for example, and IAGOS data will let her dig deeper into that continent's role in recent trends. She'll also compare tropical ozone measurements from IAGOS, taken above polluted regions, with measurements from the NASA Atmospheric Tomography (ATom) field campaign, which measured trace gases and aerosol particles in more remote, less polluted regions including the tropics. And she'll look at measurements from TROPOMI, an instrument on board a European Space Agency satellite gathering information on atmospheric composition."We want to understand the variability of ozone and its precursors and the impact of polluted regions on remote regions," Gaudel said. "So we're using the best tools we have, including IAGOS, ATom data and TROPOMI data, to get profiles and columns of ozone and its precursors from different kinds of human activities and natural sources."

Ozone Holes

August 18, 2020

https://www.sciencedaily.com/releases/2020/08/200818142104.htm

Exploding stars may have caused mass extinction on Earth, study shows

Imagine reading by the light of an exploded star, brighter than a full moon -- it might be fun to think about, but this scene is the prelude to a disaster when the radiation devastates life as we know it. Killer cosmic rays from nearby supernovae could be the culprit behind at least one mass extinction event, researchers said, and finding certain radioactive isotopes in Earth's rock record could confirm this scenario.

A new study led by University of Illinois, Urbana-Champaign astronomy and physics professor Brian Fields explores the possibility that astronomical events were responsible for an extinction event 359 million years ago, at the boundary between the Devonian and Carboniferous periods.The paper is published in the The team concentrated on the Devonian-Carboniferous boundary because those rocks contain hundreds of thousands of generations of plant spores that appear to be sunburnt by ultraviolet light -- evidence of a long-lasting ozone-depletion event."Earth-based catastrophes such as large-scale volcanism and global warming can destroy the ozone layer, too, but evidence for those is inconclusive for the time interval in question," Fields said. "Instead, we propose that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the protracted loss of ozone.""To put this into perspective, one of the closest supernova threats today is from the star Betelgeuse, which is over 600 light-years away and well outside of the kill distance of 25 light-years," said graduate student and study co-author Adrienne Ertel.The team explored other astrophysical causes for ozone depletion, such as meteorite impacts, solar eruptions and gamma-ray bursts. "But these events end quickly and are unlikely to cause the long-lasting ozone depletion that happened at the end of the Devonian period," said graduate student and study co-author Jesse Miller.A supernova, on the other hand, delivers a one-two punch, the researchers said. The explosion immediately bathes Earth with damaging UV, X-rays and gamma rays. Later, the blast of supernova debris slams into the solar system, subjecting the planet to long-lived irradiation from cosmic rays accelerated by the supernova. The damage to Earth and its ozone layer can last for up to 100,000 years.However, fossil evidence indicates a 300,000-year decline in biodiversity leading up to the Devonian-Carboniferous mass extinction, suggesting the possibility of multiple catastrophes, maybe even multiple supernovae explosions. "This is entirely possible," Miller said. "Massive stars usually occur in clusters with other massive stars, and other supernovae are likely to occur soon after the first explosion."The team said the key to proving that a supernova occurred would be to find the radioactive isotopes plutonium-244 and samarium-146 in the rocks and fossils deposited at the time of extinction. "Neither of these isotopes occurs naturally on Earth today, and the only way they can get here is via cosmic explosions," said undergraduate student and co-author Zhenghai Liu.The radioactive species born in the supernova are like green bananas, Fields said. "When you see green bananas in Illinois, you know they are fresh, and you know they did not grow here. Like bananas, Pu-244 and Sm-146 decay over time. So if we find these radioisotopes on Earth today, we know they are fresh and not from here -- the green bananas of the isotope world -- and thus the smoking guns of a nearby supernova."Researchers have yet to search for Pu-244 or Sm-146 in rocks from the Devonian-Carboniferous boundary. Fields' team said its study aims to define the patterns of evidence in the geological record that would point to supernova explosions."The overarching message of our study is that life on Earth does not exist in isolation," Fields said. "We are citizens of a larger cosmos, and the cosmos intervenes in our lives -- often imperceptibly, but sometimes ferociously."Also participating in the study were scientists from the University of Kansas; Kings College, UK; the European Organization for Nuclear Research, Switzerland; the National Institute of Chemical Physics and Biophysics, Estonia; the United States Air Force Academy; and Washburn University.The Science and Technology Facilities Council and the Estonian Research Council supported this study.

Ozone Holes

July 28, 2020

https://www.sciencedaily.com/releases/2020/07/200727194737.htm

Lockdown saw modest drop in China air pollution, study finds

Large improvements of air quality in China during the COVID-19 lockdown have been widely reported, but new research reveals that the two pollutants most harmful to human health, fine particulate matter (PM2.5) and ozone, were only slightly reduced.

The study, by scientists from the University of Leeds, UK and the Southern University of Science and Technology, China, analysed air pollutant concentrations from China's national network of around 1,300 monitoring stations to quantify the response of air pollution across China during the COVID-19 lockdown.They found that the falls in some air pollutants like nitrogen dioxide (NOThe study is published today in the IOP Publishing journalSenior author Professor Dominick Spracklen, from the University of Leeds, said: "Although China's air quality has improved in recent years, indoor and outdoor air pollution still has serious health impacts, with 12 per cent of deaths in China in 2017 attributable to it."Understanding trends in air quality is therefore essential to assess the effectiveness of recent air quality measures and help inform future air pollution mitigation. The application of control measures during the COVID-19 outbreak enabled us to analyse the potential air quality improvements resulting from a reduction in emissions."To understand the impact of the control measures during the COVID-19 outbreak, the researchers compared pollutant concentrations in 2020 with expected concentrations had the COVID-19 outbreak not occurred.They used a time series of China-wide measurements of key pollutant concentrations, from January 2015 to April 2020, to isolate the changes during the lockdown period compared with concentrations otherwise expected based on recent trends, seasonality, and the effects of the Lunar New Year (the precise date of which changes from year to year).Lead author Ben Silver, from the University of Leeds, said: "During the lockdown period in China, defined as January 23rd to March 31st, 2020, we found that the largest reductions occurred in NO"Much smaller reductions were observed for other pollutants. PMCo-author Xinyue He, from the Southern University of Science and Technology, Shenzen, China, said: "Chinese NO"PMProfessor Spracklen added: "The modest improvement in air quality during the lockdown, despite very large reductions in emissions from some sources such as traffic, highlights the challenge facing China as it tries to further improve air quality."Our study provides insight into the effects of future emission reductions and can help inform development of effective air pollution mitigation strategies."

Ozone Holes

July 20, 2020

https://www.sciencedaily.com/releases/2020/07/200720093238.htm

Geoengineering is just a partial solution to fight climate change

Could we create massive sulfuric acid clouds that limit global warming and help meet the 2015 Paris international climate goals, while reducing unintended impacts?

Yes, in theory, according to a Rutgers co-authored study in the journal But the regional impacts of geoengineering, including on precipitation and the Antarctic ozone layer hole, depend on how much greenhouse gas emissions from humanity are being reduced simultaneously. If carbon dioxide emissions from burning coal, oil and natural gas continue unabated, geoengineering would not prevent large decreases in precipitation and depletion of the life-sustaining ozone layer. If society launches massive efforts to reduce carbon emissions, remove carbon dioxide from the atmosphere and adapt to climate change, small doses of geoengineering may help reduce the most dangerous aspects of global warming, the study says."Our research shows that no single technology to combat climate change will fully address the growing crisis, and we need to stop burning fossil fuels and aggressively harness wind and solar energy to power society ASAP," said co-author Alan Robock, a Distinguished Professor in the Department of Environmental Sciences in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. "This mitigation is needed whether society ever decides to deploy geoengineering or not."Using a climate model, scientists studied whether it's possible to create sulfuric acid clouds in the stratosphere to reflect solar radiation and limit global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) or 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial temperatures. Those two goals were set at the 2015 United Nations climate change conference in Paris to try to reduce the negative impacts of global warming.Robock noted that the study was done with only one climate model that addressed different global warming and geoengineering scenarios. Other studies are needed to check the robustness of the results and to further examine the potential risks of any geoengineering scheme.Lili Xia, a Rutgers research scientist, co-authored study. Scientists at the National Center for Atmospheric Research, Cornell University, University of Colorado, Boulder, Utrecht University, Delft University of Technology, University of Texas, Rio Grande Valley, Indiana University and Pacific Northwest National Laboratory contributed.

Ozone Holes

June 30, 2020

https://www.sciencedaily.com/releases/2020/06/200630155750.htm

Removing toxic chemicals from water: New environmentally-friendly method

Researchers from Swansea University have developed a new environmentally friendly method for removing toxic chemicals from water.

A newly invented machine, called the Matrix Assembly Cluster Source (MACS), has been used to design a breakthrough water treatment method using a solvent-free approach.The research, from The Institute for Innovative Materials, Processing and Numerical Technologies (IMPACT) within the College of Engineering at Swansea University, was funded by the EPSRC and led by Professor Richard Palmer.Professor Richard Palmer explains: "The harmful organic molecules are destroyed by a powerful oxidising agent, ozone, which is boosted by a catalyst. Usually such catalysts are manufactured by chemical methods using solvents, which creates another problem -- how to deal with the effluents from the manufacturing process?The Swansea innovation is a newly invented machine that manufactures the catalyst by physical methods, involving no solvent, and therefore no effluent. The new technique is a step change in the approach to water treatment and other catalytic processes."Professor Palmer continues: "Our new approach to making catalysts for water treatments uses a physical process which is vacuum-based and solvent free method. The catalyst particles are clusters of silver atoms, made with the newly invented MACS machine.It solves the long-standing problem of low cluster production rate -- meaning, for the first time, it is now possible to produce enough clusters for study at the test-tube level, with the potential to then scale-up further to the level of small batch manufacturing and beyond."The clusters are approximately 10,000 times smaller than the width of a human hair and have been of significant interest to researchers because of their unique properties. However, due to the inadequate rate of cluster production, research in this area has been limited.The new MACS method has changed this -- it scales up the intensity of the cluster beam to produce enough grams of cluster powder for practical testing. The addition of ozone to the powder then destroys pollutant chemicals from water, in this case nitrophenol.On the future potential of this breakthrough technology, Professor Palmer summarises: "The MACS approach to the nanoscale design of functional materials opens up completely new horizons across a wide range of disciplines -- from physics and chemistry to biology and engineering. Thus, it has the power to enable radical advances in advanced technology -- catalysts, biosensors, materials for renewable energy generation and storage.It seems highly appropriate that the first practical demonstration of Swansea's environmentally friendly manufacturing process concerns something we are all concerned about -- clean water!"

Ozone Holes

May 27, 2020

https://www.sciencedaily.com/releases/2020/05/200527150158.htm

Erosion of ozone layer responsible for mass extinction event

Researchers at the University of Southampton have shown that an extinction event 360 million years ago, that killed much of the Earth's plant and freshwater aquatic life, was caused by a brief breakdown of the ozone layer that shields the Earth from damaging ultraviolet (UV) radiation. This is a newly discovered extinction mechanism with profound implications for our warming world today.

There have been a number of mass extinction in the geological past. Only one was caused by an asteroid hitting the Earth, which was 66 million years ago when the dinosaurs became extinct. Three of the others, including the end Permian Great Dying, 252 million years ago, were caused by huge continental scale volcanic eruptions that destabilised the Earth's atmospheres and oceans.Now, scientists have found evidence showing it was high levels of UV radiation which collapsed forest ecosystems and killed off many species of fish and tetrapods (our four limbed ancestors) at the end of the Devonian geological period, 359 million years ago. This damaging burst of UV radiation occurred as part of one of the Earth's climate cycles, rather than being caused by a huge volcanic eruption.The ozone collapse occurred as the climate rapidly warmed following an intense ice age and the researchers suggest that the Earth today could reach comparable temperatures, possibly triggering a similar event. Their findings are published in the journal The team collected rock samples during expeditions to mountainous polar-regions in East Greenland, which once formed a huge ancient lake bed in the arid interior of the Old Red Sandstone Continent, made up of Europe and North America. This lake was situated in the Earth's southern hemisphere and would have been similar in nature to modern day Lake Chad on the edge of the Sahara Desert.Other rocks were collected from the Andean Mountains above Lake Titicaca in Bolivia. These South American samples were from the southern continent of Gondwana, which was closer to the Devonian South Pole. They held clues as to what was happening at the edge of the melting Devonian ice sheet, allowing a comparison between the extinction event close to the pole and close to the equator.Back in the lab, the rocks were dissolved in hydrofluoric acid, releasing microscopic plant spores (like pollen, but from fern like plants that didn't have seeds or flowers) which had lain preserved for hundreds of millions of years. On microscopic examination, the scientists found many of the spores had bizarrely formed spines on their surface -- a response to UV radiation damaging their DNA. Also, many spores had dark pigmented walls, thought to be a kind of protective 'tan', due to increased and damaging UV levels.The scientists concluded that, during a time of rapid global warming, the ozone layer collapsed for a short period, exposing life on Earth to harmful levels of UV radiation and triggering a mass extinction event on land and in shallow water at the Devonian-Carboniferous boundary.Following melting of the ice sheets, the climate was very warm, with the increased heat above continents pushing more naturally generated ozone destroying chemicals into the upper atmosphere. This let in high levels of UV-B radiation for several thousand years.Lead researcher Professor John Marshall, of the University of Southampton's School of Ocean and Earth Science, who is a National Geographic Explorer, comments: "Our ozone shield vanished for a short time in this ancient period, coinciding with a brief and quick warming of the Earth. Our ozone layer is naturally in a state of flux -- constantly being created and lost -- and we have shown this happened in the past too, without a catalyst such as a continental scale volcanic eruption."During the extinction, plants selectively survived, but were enormously disrupted as the forest ecosystem collapsed. The dominant group of armoured fish became extinct. Those that survived -- sharks and bony fish -- remain to this day the dominant fish in our ecosystems.These extinctions came at a key time for the evolution of our own ancestors, the tetrapods. These early tetrapods are fish that evolved to have limbs rather than fins, but still mostly lived in water. Their limbs possessed many fingers and toes. The extinction reset the direction of their evolution with the post-extinction survivors being terrestrial and with the number of fingers and toes reduced to five.Professor Marshall says his team's findings have startling implications for life on Earth today: "Current estimates suggest we will reach similar global temperatures to those of 360 million years ago, with the possibility that a similar collapse of the ozone layer could occur again, exposing surface and shallow sea life to deadly radiation. This would move us from the current state of climate change, to a climate emergency."The remote locations visited in East Greenland are very difficult to access, with travel involving light aircraft capable of landing directly on the tundra. Transport within the vast field area was by inflatable boats equipped with outboard motors, all of which had to fit in the small aircraft.All field logistics was organised by CASP, an independent charitable trust based in Cambridge specialising in remote geological fieldwork. Mike Curtis, Managing Director of CASP says: "We have a history of assisting research geologists such as John Marshall and colleagues to access remote field areas and we are particularly pleased that their research has proved to have such potentially profound implications."

Ozone Holes

May 14, 2020

https://www.sciencedaily.com/releases/2020/05/200514131712.htm

CFC replacements are a source of persistent organic pollution in the Arctic

Substances used to replace ozone-depleting chlorofluorocarbons (CFCs) may be just as problematic as their predecessors, a new study shows.

In 1987, Canada implemented the Montreal Protocol, a global agreement to protect Earth's ozone layer by ceasing the use of substances like CFCs. Unfortunately, the CFC-replacement substances used to replace them are proving problematic as well, with accumulating levels of their degradation products recently found in the Canadian Arctic."In many ways, the degradation products from these substances may be just as concerning as the original chemical they were meant to replace," said Alison Criscitiello, director of the Canadian Ice Core Lab (CICL), housed in the University of Alberta's Faculty of Science. "We are seeing significant levels of these short-chain acids accumulating in the Devon Ice Cap, and this study links some of them directly to CFC replacement compounds."An ice core drilled on the summit of Devon Ice Cap in the Canadian high Arctic shows a tenfold increase in short-chain perfluorocarboxylic acid (scPFCA) deposition between 1986 and 2014. scPFCAs form through atmospheric oxidation of several industrial chemicals, some of which are CFC replacement compounds. scPFCAs are highly mobile persistent organic pollutants and belong to the class of so-called "forever chemicals" because they do not break down. A few preliminary studies have shown toxicity of these substances to plants and invertebrates."This is the first multi-decadal temporal record of scPFCA deposition in the Arctic," explained Criscitiello. "Our results suggest that the CFC-replacement compounds mandated by the Montreal Protocol are the dominant source of some scPFCAs to remote regions."Over the past four years, Criscitiello and colleagues drilled four ice cores across the eastern Canadian high Arctic. This interdisciplinary work is thanks to a strong collaboration between Criscitiello and the labs of York University atmospheric chemist Cora Young and Environment and Climate Change Canada research scientist Amila De Silva.These same Canadian Arctic ice cores also contain significant levels of perfluoroalkyl acids (PFAAs). These results demonstrate that both perfluoroalkyl carboxylic acids (PFCAs) and perfluorooctane sulfonate (PFOS) have continuous and increasing deposition on the Devon Ice Cap despite North American and international regulations and phase-outs. This is the likely result of ongoing manufacture, use, and emissions of these persistent pollutants, as well as their precursors and other new compounds in regions outside of North America."These results show the need for a more holistic approach when deciding to ban and replace chemical compounds," explained Criscitiello. "Chemicals degrade, and developing a strong understanding of how they degrade in the environment, and what they degrade to, is vital."

Ozone Holes

May 11, 2020

https://www.sciencedaily.com/releases/2020/05/200511124444.htm

COVID-19 lockdowns significantly impacting global air quality

Levels of two major air pollutants have been drastically reduced since lockdowns began in response to the COVID-19 pandemic, but a secondary pollutant -- ground-level ozone -- has increased in China, according to new research.

Two new studies in AGU's journal In addition to nitrogen dioxide, one of the new studies finds particulate matter pollution (particles smaller than 2.5 microns) has decreased by 35 percent in northern China. Particulate matter is composed of solid particles and liquid droplets that are small enough to penetrate deep into the lungs and cause damage.The two new papers are part of an ongoing special collection of research in AGU journals related to the current pandemic.Such a significant drop in emissions is unprecedented since air quality monitoring from satellites began in the 1990s, said Jenny Stavrakou, an atmospheric scientist at the Royal Belgian Institute for Space Aeronomy in Brussels and co-author of one of the papers. The only other comparable events are short-term reductions in China's emissions due to strict regulations during events like the 2008 Beijing Olympics.The improvements in air quality will likely be temporary, but the findings give scientists a glimpse into what air quality could be like in the future as emissions regulations become more stringent, according to the researchers."Maybe this unintended experiment could be used to understand better the emission regulations," Stavrakou said. "It is some positive news among a very tragic situation."However, the drop in nitrogen dioxide pollution has caused an increase in surface ozone levels in China, according to one of the new studies. Ozone is a secondary pollutant formed when sunlight and high temperature catalyze chemical reactions in the lower atmosphere. Ozone is harmful to humans at ground-level, causing pulmonary and heart disease.In highly polluted areas, particularly in winter, surface ozone can be destroyed by nitrogen oxides, so ozone levels can increase when nitrogen dioxide pollution goes down. As a result, although air quality has largely improved in many regions, surface ozone can still be a problem, according to Guy Brasseur, an atmospheric scientist at the Max Planck Institute for Meteorology in Hamburg, Germany, and lead author of one of the new studies."It means that by just reducing the [nitrogen dioxide] and the particles, you won't solve the ozone problem," Brasseur said.Stavrakou and her colleagues used satellite measurements of air quality to estimate the changes in nitrogen dioxide pollution over the major epicenters of the outbreak: China, South Korea, Italy, Spain, France, Germany, Iran and the United States.They found that nitrogen dioxide pollution decreased by an average of 40 percent over Chinese cities and by 20 to 38 percent over Western Europe and the United States during the 2020 lockdown, as compared to the same time in 2019.However, the study found nitrogen dioxide pollution did not decrease over Iran, one of the earliest and hardest-hit countries. The authors suspect this is because complete lockdowns weren't in place until late March and before that, stay-at-home orders were largely ignored. The authors did see a dip in emissions during the Iranian New Year holiday after March 20, but this dip is observed during the celebration every year.The second study looked at air quality changes in northern China where the virus was first reported and where lockdowns have been most strict.Brasseur analyzed levels of nitrogen dioxide and several other types of air pollution measured by 800 ground-level air quality monitoring stations in northern China.Brasseur and his colleague found particulate matter pollution decreased by an average of 35 percent and nitrogen dioxide decreased by an average of 60 percent after the lockdowns began on January 23.However, they found the average surface ozone concentration increased by a factor of 1.5-2 over the same time period. At ground level, ozone forms from complex reactions involving nitrogen dioxide and volatile organic compounds (VOCs), gases emitted by a variety of household and industrial products, but ozone levels can also be affected by weather conditions and other factors.

Ozone Holes

April 21, 2020

https://www.sciencedaily.com/releases/2020/04/200421090554.htm

Nearly half of US breathing unhealthy air; record-breaking air pollution in nine cities

This year marks the 50th anniversary of the Clean Air Act, which is responsible for dramatic improvements in air quality. Despite this, a new report from the American Lung Association finds nearly half of the nation's population -- 150 million people -- lived with and breathed polluted air, placing their health and lives at risk. The 21st annual "State of the Air" report finds that climate change continues to make air pollution worse, with many western communities again experiencing record-breaking spikes in particle pollution due to wildfires. Amid the COVID-19 pandemic, the impact of air pollution on lung health is of heightened concern.

The 2020 "State of the Air" report analyzed data from 2016, 2017 and 2018, the three years with the most recent quality-assured air pollution data. Notably, those three years were among the five hottest recorded in global history. When it comes to air quality, changing climate patterns fuel wildfires and their dangerous smoke, and lead to worsened particle and ozone pollution. This degraded air quality threatens everyone, especially children, older adults and people living with a lung disease."The report finds the air quality in some communities has improved, but the 'State of the Air' finds that far too many people are still breathing unhealthy air," said American Lung Association President and CEO Harold Wimmer. "This year's report shows that climate change continues to degrade air quality and increase the risk of air pollution harming health. To protect the advances in air quality we fought for 50 years ago through the Clean Air Act, we must again act today, implementing effective policies to protect our air quality and lung health against the threat of climate change.""Air pollution is linked to greater risk of lung infection," Wimmer added. "Protecting everyone from COVID-19 and other lung infections is an urgent reminder of the importance of clean air."Each year, "State of the Air" reports on the two most widespread outdoor air pollutants, ozone pollution and particle pollution. Each is dangerous to public health and can be lethal. The 2020 "State of the Air" report found that more than 20.8 million people lived in counties that had unhealthy levels of air pollution in all categories from 2016 to 2018. Below are the report findings for each category graded.Unhealthy particles in the air come from wildfires, wood-burning stoves, coal-fired power plants, diesel engines and other sources. Particle pollution can be deadly. Technically known as PM2.5, these microscopic particles lodge deep in the lungs and can even enter the bloodstream. Particle pollution can trigger asthma attacks, heart attacks and strokes and cause lung cancer. New research also links air pollution to the development of serious diseases, such as asthma and dementia.The report has two grades for particle pollution: one for "short-term" particle pollution, or daily spikes, and one for the annual average, "year-round" level that represents the concentration of particles day-in and day-out in each location.More cities experienced more days with spikes in particle pollution in this year's report. In fact, nine western cities reached their most days ever reported. These deadly spikes were driven in large part by smoke from major wildfires in 2018, especially in California, and some locations also saw spikes from woodsmoke from heating homes. Of note, 24 of the 25 most polluted cities were located in the western region of the U.S. Nationwide, more than 53.3 million people experienced these unhealthy spikes in particle pollution.Top 10 U.S. Cities Most Polluted by Short-term Particle Pollution (24-hour PM2.5):2. Bakersfield, California3. San Jose-San Francisco-Oakland, California4. Fairbanks, Alaska5. Yakima, Washington6. Los Angeles-Long Beach, California7. Missoula, Montana8. Redding-Red Bluff, California9. Salt Lake City-Provo-Orem, Utah10. Phoenix-Mesa, ArizonaMore than 21.2 million people lived in counties with unhealthy levels of year-round particle pollution, which is more than in the last three "State of the Air" reports. Progress toward healthy air continued in many places thanks to steps taken to clean up emissions that lead to particle pollution, but 13 of the 26 most polluted cities faced worse levels of year-round particle pollution. Some cities had so many days of short-term particle pollution spikes that the sheer number led to them having higher annual averages as well.Many cities experienced their cleanest ever annual average, yet remained on the nation's most polluted list. Despite making the top 10 most polluted list, both Fresno-Madera-Hanford, California and Pittsburgh metro area tied with their previous record of cleanest air in the 21-year history of the report. And while Chicago, Cincinnati and Indianapolis made the top 25 most polluted list, each hit their cleanest ever annual average.Top 10 U.S. Cities Most Polluted by Year-Round Particle Pollution (Annual PM2.5):2. Fresno-Madera-Hanford, California3. Visalia, California4. Los Angeles-Long Beach, California5. San Jose-San Francisco-Oakland, California6. Fairbanks, Alaska7. Phoenix-Mesa, Arizona8. El Centro, California8. Pittsburgh-New Castle-Weirton, PA-OH-WV10. Detroit-Warren-Ann Arbor, MichiganOzone pollution, often referred to as smog, is a powerful respiratory irritant whose effects have been likened to a sunburn of the lung. Inhaling ozone can cause shortness of breath, trigger coughing and asthma attacks and may shorten life. Warmer temperatures driven by climate change make ozone more likely to form and harder to clean up.Significantly more people suffered unhealthy ozone pollution in the 2020 report than in the last three "State of the Air" reports. More than 137 million people lived in area county earning a failing grade for ozone pollution. This shows the changing climate's impact on air quality, as ozone pollution worsened during the global record-breaking heat years tracked in the 2020 report. However, despite making the top ten list of most ozone-polluted cities, San Jose-San Francisco-Oakland, California experienced its best-ever air quality for ozone.Top 10 Most Ozone-Polluted Cities:2. Visalia, California3. Bakersfield, California4. Fresno-Madera-Hanford, California5. Sacramento-Roseville, California6. San Diego-Chula Vista-Carlsbad, California7. Phoenix-Mesa, Arizona8. San Jose-San Francisco-Oakland, California9. Las Vegas-Henderson, Nevada10. Denver-Aurora, ColoradoThe "State of the Air" also recognizes the nation's four cleanest cities. To make the list, a city must experience no high ozone or high particle pollution days and must rank among the 25 cities with the lowest year-round particle pollution levels.Cleanest U.S. Cities (listed in alphabetical order)"The science is clear: the nation needs stronger limits on ozone and particle pollution to safeguard health, especially for children and people with lung disease," Wimmer said. "Every family has the right to breathe healthy air -- and the right to know when air pollution levels are unhealthy. The Clean Air Act is a powerful protector of public health and Americans breathe healthier air today because of this landmark law. But climate change poses increasingly dire threats to air quality and lung health, and our leaders must take immediate, significant action to safeguard the air we all breathe."

Ozone Holes

April 16, 2020

https://www.sciencedaily.com/releases/2020/04/200416135944.htm

Arctic stratospheric ozone levels hit record low in March

Ozone levels above the Arctic reached a record low for March, NASA researchers report. An analysis of satellite observations show that ozone levels reached their lowest point on March 12 at 205 Dobson units.

While such low levels are rare, they are not unprecedented. Similar low ozone levels occurred in the upper atmosphere, or stratosphere, in 1997 and 2011. In comparison, the lowest March ozone value observed in the Arctic is usually around 240 Dobson units."This year's low Arctic ozone happens about once per decade," said Paul Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "For the overall health of the ozone layer, this is concerning since Arctic ozone levels are typically high during March and April."Ozone is a highly reactive molecule comprised of three oxygen atoms that occurs naturally in small amounts. The stratospheric ozone layer, roughly 7 to 25 miles above Earth's surface, is a sunscreen, absorbing harmful ultraviolet radiation that can damage plants and animals and affecting people by causing cataracts, skin cancer and suppressed immune systems.The March Arctic ozone depletion was caused by a combination of factors that arose due to unusually weak upper atmospheric "wave" events from December through March. These waves drive movements of air through the upper atmosphere akin to weather systems that we experience in the lower atmosphere, but much bigger in scale.In a typical year, these waves travel upward from the mid-latitude lower atmosphere to disrupt the circumpolar winds that swirl around the Arctic. When they disrupt the polar winds, they do two things. First, they bring with them ozone from other parts of the stratosphere, replenishing the reservoir over the Arctic."Think of it like having a red-paint dollop, low ozone over the North Pole, in a white bucket of paint," Newman said. "The waves stir the white paint, higher amounts of ozone in the mid-latitudes, with the red paint or low ozone contained by the strong jet stream circling around the pole."The mixing has a second effect, which is to warm the Arctic air. The warmer temperatures then make conditions unfavorable for the formation of polar stratospheric clouds. These clouds enable the release of chlorine for ozone-depleting reactions. Ozone depleting chlorine and bromine come from chlorofluorocarbons and halons, the chemically active forms of chlorine and bromine derived from human-made compounds that are now banned by the Montreal Protocol. The mixing shuts down this chlorine and bromine driven ozone depletion.In December 2019 and January through March of 2020, the stratospheric wave events were weak and did not disrupt the polar winds. The winds thus acted like a barrier, preventing ozone from other parts of the atmosphere from replenishing the low ozone levels over the Arctic. In addition, the stratosphere remained cold, leading to the formation of polar stratospheric clouds which allowed chemical reactions to release reactive forms of chlorine and cause ozone depletion."We don't know what caused the wave dynamics to be weak this year," Newman said. "But we do know that if we hadn't stopped putting chlorofluorocarbons into the atmosphere because of the Montreal Protocol, the Arctic depletion this year would have been much worse."Since 2000, levels of chlorofluorocarbons and other human-made ozone-depleting substances have measurably decreased in the atmosphere and continue to do so. Chlorofluorocarbons are long-lived compounds that take decades to break down, and scientists expect stratospheric ozone levels to recover to 1980 levels by mid-century.NASA researchers prefer the term "depletion" over the Arctic, since despite the ozone layer's record low this year, the ozone loss is still much less than the annual ozone "hole" that occurs over Antarctica in September and October during Southern Hemisphere spring. For comparison, ozone levels over Antarctica typically drop to about 120 Dobson units.NASA, along with the National Oceanic and Atmospheric Administration, monitors stratospheric ozone using satellites, including NASA's Aura satellite, the NASA-NOAA Suomi National Polar-orbiting Partnership satellite and NOAA's Joint Polar Satellite System NOAA-20. The Microwave Limb Sounder aboard the Aura satellite also estimates stratospheric levels of ozone-destroying chlorine.

Ozone Holes

March 25, 2020

https://www.sciencedaily.com/releases/2020/03/200325120840.htm

International ozone treaty stops changes in Southern Hemisphere winds

Chemicals that deplete Earth's protective ozone layer have also been triggering changes in Southern Hemisphere atmospheric circulation. Now, new research in

"This study adds to growing evidence showing the profound effectiveness of the Montreal Protocol. Not only has the treaty spurred healing of the ozone layer, it's also driving recent changes in Southern Hemisphere air circulation patterns," said lead author Antara Banerjee, a CIRES Visiting Fellow at the University of Colorado Boulder who works in the Chemical Sciences Division of the National Oceanic and Atmospheric Administration (NOAA). She started this work as a Postdoctoral Fellow at Columbia University.The ozone hole, discovered in 1985, has been forming every spring in the atmosphere high over Antarctica. Ozone depletion cools the air, strengthening the winds of the polar vortex and affecting winds all the way down to the lowest layer of Earth's atmosphere. Ultimately, ozone depletion has shifted the midlatitude jet stream and the dry regions at the edge of the tropics toward the South Pole.Previous studies have linked these circulation trends to weather changes in the Southern Hemisphere, especially rainfall over South America, East Africa, and Australia, and to changes in ocean currents and salinity.The Montreal Protocol of 1987 phased out production of ozone-destroying substances such as chlorofluorocarbons (CFCs). Beginning around 2000, concentrations of those chemicals in the stratosphere started to decline and the ozone hole began to recover. In this study, Banerjee and her co-authors have shown that around the year 2000, the circulation of the Southern Hemisphere also stopped expanding polewards -- a pause or slight reversal of the earlier trends."The challenge in this study was proving our hypothesis that ozone recovery is in fact driving these atmospheric circulation changes and it isn't just a coincidence," Banerjee said.To do that, the researchers used a two-step statistical technique called detection and attribution: detecting whether certain patterns of observed wind changes are unlikely to be due to natural variability alone and, if so, whether the changes can be attributed to human-caused factors, such as emissions of ozone-depleting chemicals and COUsing computer simulations, the researchers first determined that the observed pause in circulation trends couldn't be explained by natural shifts in winds alone. Next, they isolated the effects of ozone and greenhouse gases separately.They showed that while rising CO"Identifying the ozone-driven pause in circulation trends in real-world observations confirms, for the first time, what the scientific ozone community has long predicted from theory," said John Fyfe, a scientist at Environment and Climate Change Canada and one of the paper's co-authors.With ozone beginning to recover and CO"We term this a 'pause' because the poleward circulation trends might resume, stay flat, or reverse," Banerjee said. "It's the tug of war between the opposing effects of ozone recovery and rising greenhouse gases that will determine future trends."

Ozone Holes

March 17, 2020

https://www.sciencedaily.com/releases/2020/03/200317130722.htm

Emissions of several ozone-depleting chemicals are larger than expected

In 2016, scientists at MIT and elsewhere observed the first signs of healing in the Antarctic ozone layer. This environmental milestone was the result of decades of concerted effort by nearly every country in the world, which collectively signed on to the Montreal Protocol. These countries pledged to protect the ozone layer by phasing out production of ozone-depleting chlorofluorocarbons, which are also potent greenhouse gases.

While the ozone layer is on a recovery path, scientists have found unexpectedly high emissions of CFC-11 and CFC-12, raising the possibility of production of the banned chemicals that could be in violation of the landmark global treaty. Emissions of CFC-11 even showed an uptick around 2013, which has been traced mainly to a source in eastern China. New data suggest that China has now tamped down on illegal production of the chemical, but emissions of CFC-11 and 12 emission are still larger than expected.Now MIT researchers have found that much of the current emission of these gases likely stems from large CFC "banks" -- old equipment such as building insulation foam, refrigerators and cooling systems, and foam insulation, that was manufactured before the global phaseout of CFCs and is still leaking the gases into the atmosphere. Based on earlier analyses, scientists concluded that CFC banks would be too small to contribute very much to ozone depletion, and so policymakers allowed the banks to remain.It turns out there are oversized banks of both CFC-11 and CFC-12. The banks slowly leak these chemicals at concentrations that, if left unchecked, would delay the recovery of the ozone hole by six years and add the equivalent of 9 billion metric tons of carbon dioxide to the atmosphere -- an amount that is similar to the current European Union pledge under the UN Paris Agreement to reduce climate change."Wherever these CFC banks reside, we should consider recovering and destroying them as responsibly as we can," says Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies at MIT, who is a co-author of the study. "Some banks are easier to destroy than others. For instance, before you tear a building down, you can take careful measures to recover the insulation foam and bury it in a landfill, helping the ozone layer recover faster and perhaps taking off a chunk of global warming as a gift to the planet."The team also identified an unexpected and sizable source of another ozone-depleting chemical, CFC-113. This chemical was traditionally used as a cleaning solvent, and its production was banned, except for in one particular use, as a feedstock for the manufacturing of other chemical substances. It was thought that chemical plants would use the CFC-113 without allowing much leakage, and so the chemical's use as a feedstock was allowed to continue.However, the researchers found that CFC-113 is being emitted into the atmosphere, at a rate of 7 billion grams per year -- nearly as large as the spike in CFC-11, which amounted to about 10 billion grams per year."A few years ago, the world got very upset over 10 gigagrams of CFC-11 that wasn't supposed to be there, and now we're seeing 7 gigagrams of CFC-113 that wasn't supposed to be there," says lead author of the study and MIT graduate student Megan Lickley. "The two gases are similar in terms of their ozone depletion and global warming potential. So this is a significant issue."The study appears in The new results are based on an analysis the team developed that combines two common methods for estimating the size of CFC banks around the world.The first method is a top-down approach, which looks at CFCs produced around the world, based on country-by-country reporting, and then compares these numbers to actual concentrations of the gasses and how long they persist in the atmosphere. After accounting for atmospheric destruction, the difference between a chemical's production and its atmospheric concentrations gives scientists an estimate of the size of CFC banks around the world.Based on recent international assessments that use this top-down approach, there should be no CFC banks left in the world."But those values are subject to large uncertainties: Small differences in production values or lifetimes or concentrations can lead to large differences in the bank size," Lickley notes.The second method is a bottom-up approach, which uses industry-reported values of CFC production and sales in a variety of applications such as refrigeration or foams, and estimates of how quickly each equipment type is depleting over time.The team combined the best of both methods in a Bayesian probabilistic model -- a hybrid approach that calculates the global size of CFC banks based on both atmospheric data, and country and industry-level reporting of CFC production and sales in various uses."We also allow there to be some uncertainties, because there could be reporting errors from different countries, which wouldn't be surprising at all," Solomon says. "So it's a much better quantification of the size of the bank."The CFC banks, and the sheer quantity of old equipment storing these chemicals around the world, seem to be larger than any previous estimates. The team found the amount of CFC 11 and 12 stored up in banks is about 2.1 million metric tons -- an amount that would delay ozone recovery by six years if released to the atmosphere. This CFC bank is also equivalent to about 9 billion metric tons of carbon dioxide in terms of its effect on climate change.Interestingly, the amount of both CFC-11 and CFC-12 that is being emitted from these banks is enough to account for the recently observed emissions in both gases."It really looks like, other than the extra amount being produced in China that seems to have stopped now, the rest of what we're seeing is no mystery: It's just what's coming out of the banks. That's good news," Solomon says. "It means there doesn't seem to be any further cheating going on. If there is, it's very small. And we wanted to know, if you were to recover and destroy these building foams, and replace old cooling systems and such, in a more responsible way, what more could that do for climate change?"To answer that, the team explored several theoretical policy scenarios and their potential effect on the emissions produced by CFC banks.An "opportunity lost" scenario considers what would have happened if all banks were destroyed back in 2000 -- the year that many developed countries agreed to phase out CFC production. If this scenario had played out, the measure would have saved the equivalent of 25 billion metric tons of carbon dioxide between 2000 and 2020, and there would be no CFC emissions lingering now from these banks.A second scenario predicts CFC emissions in the atmosphere if all banks are recovered and destroyed in 2020. This scenario would save the equivalent of 9 billion metric tons of carbon dioxide emitted to the atmosphere. If these banks were destroyed today, it would also help the ozone layer recover six years faster."We lost an opportunity in 2000, which is really sad," Solomon says. "So let's not miss it again."This research was supported, in part, by VoLo foundation. Solomon is also supported by a Lee and Geraldine Martin Professorship.

Ozone Holes

March 12, 2020

https://www.sciencedaily.com/releases/2020/03/200312101033.htm

Can poor air quality make you gain weight?

Breathing dirty air takes a heavy toll on gut bacteria, boosting risk of obesity, diabetes, gastrointestinal disorders and other chronic illnesses, new University of Colorado Boulder research suggests.

The study, published online in the journal The gaseous pollutant ozone, which helps make up Denver's infamous 'brown cloud' -- is particularly hazardous, the study found, with young adults exposed to higher levels of ozone showing less microbial diversity and more of certain species associated with obesity and disease."We know from previous research that air pollutants can have a whole host of adverse health effects," said senior author Tanya Alderete, an assistant professor of integrative physiology, pointing to studies linking smog with Type 2 diabetes, weight gain and inflammatory bowel diseases. "The takeaway from this paper is that some of those effects might be due to changes in the gut."The study comes at a time when air quality in many U.S. cities is worsening after decades of improvement. In December, the Environmental Protection Agency downgraded the Denver metro and north Front Range regions to "serious non-attainment" status for failing to meet national ozone standards.Regions of eight other states, including some in California, Texas, Illinois, Connecticut, Indiana, New Jersey, New York and Wisconsin, were also penalized for high ozone. Worldwide, according to research published this month, air pollution kills 8.8 million people annually -- more than smoking or war.While much attention has been paid to respiratory health, Alderete's previous studies have shown pollution can also impair the body's ability to regulate blood sugar and influence risk for obesity. Other research has shown visits to emergency rooms for gastrointestinal problems spike on high pollution days, and youth with high exposure to traffic exhaust have greater risk of developing Crohn's disease.To investigate just what might be going on inside the gut, Alderete's team used cutting-edge whole-genome sequencing to analyze fecal samples from 101 young adults in Southern California.The researchers looked at data from air-monitoring stations near the subjects' addresses to calculate their previous-year exposure to ozone (which forms when emissions from vehicles are exposed to sunlight), particulate matter (hazardous particles suspended in the air), and nitrous oxide (a toxic byproduct of burning fossil fuel).Of all the pollutants measured, ozone had the greatest impact on the gut by far, accounting for about 11% of the variation seen between study subjects -- more of an impact than gender, ethnicity or even diet. Those with higher exposure to ozone also had less variety of bacteria living in their gut."This is important since lower (bacteria) diversity has been linked with obesity and Type 2 diabetes," noted Alderete.Subjects with higher exposure to ozone also had a greater abundance of a specific species called Bacteroides caecimuris. That's important, because some studies have associated high levels of Bacteroides with obesty.In all, the researchers identified 128 bacterial species influenced by increased ozone exposure. Some may impact the release of insulin, the hormone responsible for ushering sugar into the muscles for energy. Other species can produce metabolites, including fatty acids, which help maintain gut barrier integrity and ward off inflammation."Ozone is likely changing the environment of your gut to favor some bacteria over others, and that can have health consequences," said Alderete.The study was relatively small and has some limitations, including the fact that stool samples were taken only once.Alderete is now moving ahead with a larger, more expansive study of young adults in the Denver area. Thanks to a new grant from the nonprofit Health Effects Institute, she's also exploring how prenatal or early-life exposure to air pollution impacts the formation of the gut microbiome in 240 infants.She said she hopes her work will ultimately influence policymakers to consider moving parks, playgrounds and housing developments away from busy roads and high pollution areas, and invest more in meeting or exceeding air quality standards."A lot of work still needs to be done, but this adds to a growing body of literature showing that human exposure to air pollution can have lasting, harmful effects on human health."

Ozone Holes

February 5, 2020

https://www.sciencedaily.com/releases/2020/02/200205084151.htm

Treating wastewater with ozone could convert pharmaceuticals into toxic compounds

With water scarcity intensifying, wastewater treatment and reuse are gaining popularity. But some methods for killing microbes in wastewater create disinfection byproducts (DBPs) that could be harmful to human health. Now researchers have found that ozone treatment and subsequent chlorination can convert trace amounts of some pharmaceuticals in wastewater into DBPs called halonitromethanes. They report their results in

The combination of ozone and chlorine kills most bacteria and viruses in wastewater. Compared with chlorine treatment alone, ozone also reduces the formation of many DBPs. Recently, however, scientists have discovered that ozone can increase the formation of potentially toxic halonitromethanes, such as chloropicrin, in chlorine-treated wastewater. Jiaming Lily Shi and Daniel McCurry wanted to determine which molecules in the wastewater were being converted to chloropricin and how.To find out, the researchers collected wastewater samples from three treatment plants in Southern California. The team discovered that ozone treatment produced nitromethane, which could have been formed from some nitrogen-containing drugs in the wastewater, including stimulants such as ephedrine and methamphetamine and certain antidepressants. Then, chlorination transformed the nitromethane into chloropricin. The pharmaceuticals, which enter wastewater through sewage, are not removed completely by conventional wastewater treatment. Future work should address how effectively processes that occur after ozone treatment can remove the nitromethane intermediate, the researchers say.

Ozone Holes

February 4, 2020

https://www.sciencedaily.com/releases/2020/02/200204112524.htm

All things considered, wooden pallets are more eco-friendly than plastic pallets

Weighing in on a debate that has raged for decades, Penn State researchers, after conducting a series of ultra-detailed comparisons, have declared that shipping pallets made of wood are slightly more environmentally friendly and sustainable than those made of plastic.

"Few people realize the significance of this issue -- there are about 700 million pallets produced and recycled each year in the United States alone," said Chuck Ray, associate professor of ecosystem science and management in the College of Agricultural Sciences. "There are 4 billion pallets in use in this country."Researchers compared the long-term performance of treated wooden and plastic pallets through a detailed, cradle-to-grave life-cycle assessment, and conducted an analysis of treatments required to kill pests such as insects. They investigated and evaluated the environmental impacts of resources consumed and emissions released by wooden and plastic pallets throughout their life cycles.In the study, the environmental impacts of the pallets were compared on a one-trip basis and 100,000-trips basis, under nine impact categories chosen by researchers because of their environmental relevance. The categories included influence on ozone layer depletion, respiratory organics, aquatic ecotoxicity, terrestrial ecotoxicity, land occupation, aquatic acidification, aquatic eutrophication, global warming and non-renewable energy.In findings published today (Feb. 3) in the "It should be noted that wooden pallets that are heat-treated to kill pests incur a carbon footprint 20% to 30% lower than those treated with methyl bromide fumigation," Ray said. "Methyl bromide gas has been blamed for depleting the Earth's ozone layer. And theoretical calculations of the resource consumption and emissions of radio-frequency treatment of pallets suggest that the new dielectric technology may provide a lower-carbon alternative to both conventionally treated wooden pallets or plastic pallets."Molded plastic pallets, typically, have a much longer life cycle than wooden pallets because plastic pallets are usually not broken or damaged and normally can travel more than 200 round trips before being taken out of service, Ray noted. Plastic pallets are made of sturdy, hardened material and are built to last longer. But they are typically derived from petroleum or natural gas products, which greatly increases their carbon footprint."What was lacking in this whole arena was a comprehensive life-cycle analysis, and that is what this study provides," Ray said. "More than a decade ago, other studies were commissioned by the wood pallet industry and by the plastic pallet industry, and of course those results favored the funders. This is the first academic, peer-reviewed study related to pallets, and it was funded entirely by Penn State and is unbiased."With current concerns about climate change and in view of the massive amount of resources consumed to make many millions of pallets, assessing their carbon footprint is important, Ray believes. With 40 percent of all hardwood produced in the United States going into pallet production, he added, it is critical to know if wooden pallets are ecologically acceptable."Because I have worked my whole career in the wood products industry, I have gained a special appreciation for the benefits of wood as an environmentally friendly product," said Ray. "The topic interests me. It did not occur to me to do this research until the plastic pallet industry started talking about their products as environmentally superior. I questioned that statement and decided to do life-cycle analyses."Also involved in the research were Sebastian Anil, now with Microsoft; Junfeng Ma, now with Mississippi State University; Gul Kremer, now with Iowa State University; and Shirin Shahidi, a graduate student in the Department of Ecosystem Science and Management when the research was conducted.

Ozone Holes

January 27, 2020

https://www.sciencedaily.com/releases/2020/01/200127134841.htm

Another reason to reduce human-made ozone: To cool a warming planet

While elected officials in the U.S. debate a proposed "Green New Deal" and U.S. President Donald Trump derides "prophets of doom" in Davos, environmental scientists continue to gather evidence about how changes to industry could mitigate the harms of climate change.

In a News and Views article in Felzer writes: "The study [by Nadine Unger et al]...assesses the effect of reducing ozone precursors in seven different economic emission sectors, the most important of which turn out to be energy (electricity and heat production from fossil fuel burning), industry (fossil fuels burned on site), road transportation and agriculture.Unger et al. ran an Earth system model, linking climate to atmospheric chemistry, to explore the global effects on photosynthesis of reducing emissions from these sectors by 50%. Ozone pollution resulted in 9-13% reductions in photosynthesis in the aforementioned polluted regions. Cleaning up ozone precursors in the transportation, energy, industrial or agricultural sectors led to 13-16% gains in photosynthesis in eastern China, and 16-23% gains in the eastern United States and Europe due to the transportation and energy sectors. Benefits were 2-3 times larger in croplands and grasslands than forests. A 50% reduction in ozone pollution from just the transportation and energy sectors resulted in an increase in photosynthesis equivalent to the amount of carbon lost by fire each year."According to Felzer, Unger and colleagues ultimately conclude that the mitigation potential resulting from addressing ozone pollution would result in a 15% increase in the size of the current land sink for carbon.From the perspective of human health impacts, there is "good" ozone and "bad" ozone. Natural ozone in the second major layer of Earth's atmosphere has a protective effect for humans, blocking the sun's harmful ultraviolet (UV) rays. Human-made ozone, a byproduct of fossil fuel production and other industrial processes, gets trapped in the atmospheric layer closest to earth and has been shown to be harmful to human health, as well as to plants, trees and crops.Human-made ozone at ground-level inhibits plant photosynthesis by directly damaging some of the plant cells responsible for it."It affects different plants differently, for example doing more damage to crops than to trees at similar doses...," he writes. "Global climate models indicate that ozone limits photosynthesis and vegetation growth in polluted regions such as the eastern United States, eastern China, and Europe...This then reduces the carbon sequestration potential of these regions..."Reducing ozone, concludes Felzer, will help vegetation to grow better and take up more Carbon Dioxide, while also reducing unhealthy pollutants such as nitrogen oxides and volatile organic compounds (VOCs).Political debates and rhetoric aside, it is a conclusion that supports reducing human-made ozone for the health of humans, as well as the planet on which all life depends.

Ozone Holes

January 27, 2020

https://www.sciencedaily.com/releases/2020/01/200127134829.htm

Cutting road transport pollution could help plants grow

Cutting emissions of particular gases could improve conditions for plants, allowing them to grow faster and capture more carbon, new research suggests.

A cocktail of gases -- including nitrogen oxides, carbon monoxide, volatile organic compounds and methane -- combines in the atmosphere to form ozone.Ozone at the Earth's surface limits photosynthesis, reducing plants' ability to grow.University of Exeter researchers say cutting emissions of ozone-forming gases offers a "unique opportunity" to create a "natural climate solution."A 50% cut in emissions of these gases from the seven largest human-made sources -- including road transport (the largest emitter) and energy production -- would help plants contribute to "negative carbon emissions," the study says."Ecosystems on land currently slow global warming by storing about 30% of our carbon dioxide emissions every year," said Professor Nadine Unger, of the University of Exeter."This carbon capture is being undermined by ozone pollution."Our findings suggest the largest losses of plant productivity are in the eastern United States, Europe and eastern China, which all have high levels of surface ozone pollution."The impact on plant growth in these areas is estimated to be 5-20% annually."Ozone is not emitted directly but forms in the atmosphere during complex chemical reactions of carbon monoxide, methane, non-methane volatile organic compounds and nitrogen oxides.The seven areas of human activity that emit the largest amounts of these gases are agriculture, residential, energy, industry, road transportation, waste/landfill and shipping.The study says a target of cutting these specific emissions by 50% is "large but plausible," citing examples of cuts already made in some industries."Deep cuts in air pollutant emissions from road transportation and the energy sector are the most effective mitigation measures for ozone-induced loss of plant productivity in eastern China, the eastern United States, Europe and globally," said Professor Unger."Our results suggest mitigation of ozone vegetation damage is a unique opportunity to contribute to negative carbon emissions, offering a natural climate solution that links fossil fuel emission abatement, air quality and climate."However, achieving these benefits requires ambitious mitigation efforts in multiple sectors."

Ozone Holes

January 22, 2020

https://www.sciencedaily.com/releases/2020/01/200122154336.htm

Despite less ozone pollution, not all plants benefit

Breathe easy: Concentrations of ozone in the air have decreased over large parts of the country in the past several decades.

But not too easy.Policies and new technologies have reduced emissions of precursor gases that lead to ozone air pollution, but despite those improvements, the amount of ozone that plants are taking in has not followed the same trend, according to Florida State University researchers. Their findings are published in the journal "Past studies of plant damage from ozone have been overly optimistic about what the improving ozone air quality means for vegetation health," said Christopher Holmes, the Werner A. and Shirley B. Baum assistant professor of meteorology in the Department of Earth, Ocean, and Atmospheric Science.Ozone is a gas made of three oxygen molecules. In the upper levels of the atmosphere, it is helpful for life on Earth because it keeps too much ultraviolet radiation from reaching the planet's surface. But when it's found at ground level, ozone is a pollutant that can damage the lungs. It's also toxic for plants, and present-day levels of the pollutant have cut global grain yields by up to 15 percent, resulting in global losses of soybean, wheat, rice and maize valued at $10 billion to $25 billion annually.The falling levels of ozone pollution are good news for human health, but FSU researchers wanted to know if plants were seeing benefits too. To answer this question, Allison Ronan, a former graduate student, and Jason Ducker, a postdoctoral researcher at FSU, worked with Holmes and another researcher to track the amount of ozone plants sucked up through pores on their leaves over 10 years at more than 30 test sites. They compared those trends to measurements of atmospheric ozone.As they expected, the ozone concentrations in the air decreased at most of their study sites, but, surprisingly, the ozone uptake into plants at the sites didn't necessarily go down at the same time. In fact, at many sites, atmospheric ozone concentrations fell while the ozone uptake into plants rose.The different trends happen because plants can open and close the stomata pores on their leaves in response to weather, especially light, temperature, moisture, drought and other environmental conditions. If the stomata close, the plants cease taking up ozone, regardless of the concentration in the surrounding air. That means the ozone uptake into leaves doesn't exactly track the amount of ozone in the air. The FSU scientists found that these environmental factors have more impact on the ozone dose the plants receive than the amount of ozone in the atmosphere."We know that weather and growing conditions vary a lot from year to year, and that variability in weather turns out to be more important for driving the trends and variability in ozone uptake into plants than the concentrations in the surrounding air," Holmes said. "With decreasing ozone concentrations, we're moving in the right direction, but the benefits for crops and vegetation may not be apparent until the air quality improvements have persisted longer."The FSU team identified the differing trends by using a dataset developed by Holmes' research group. The dataset, called SynFlux, fuses measurements from air quality networks with data from field sites that monitor energy flows between vegetation and the atmosphere. It enabled the team to study ozone uptake trends at many more sites than has previously been possible.Future studies of plant damage and accompanying economic losses need to avoid relying primarily on measures of ozone concentration in the atmosphere and look at ozone uptake instead, researchers said."With the SynFlux dataset that we have developed, we've now got the information to do that on a large scale at many sites across multiple continents," Holmes said. "We're just scratching the surface of what we can learn about air pollution impacts on vegetation using this tool."Jordan L. Schnell at Northwestern University contributed to this research. This work was supported by the Winchester Fund at Florida State University, NASA and the National Science Foundation.

Ozone Holes

January 21, 2020

https://www.sciencedaily.com/releases/2020/01/200121112911.htm

Brazilian wildfire pollution worsens air quality in distant cities

Wildfires in south eastern Brazil produce airborne pollution that worsens air quality in major cities such as Sao Paulo -- cancelling out efforts to improve the urban environment and posing health risks to citizens, according to a new study.

The planet is frequently affected by smoke from fires caused by humans and natural processes. Australia, California and other regions are prone to seasonal wildfires and smoke from wildfires and agricultural burns worsening air quality in places up to 2,000?km away.Most wildfires in Brazil occur in the dry season between July and September in the areas of Amazon and Cerrado -- mostly agriculture-related fires -- and the Pampas. Depending on the weather, long-range transport of smoke affects the air quality of small and large cities downwind of the fire spots, including the 'megacity' of Sao Paulo.Burning biomass produces increased quantities of low-lying ozone due, in part, to the South Atlantic subtropical high pressure system. Transported considerable distances from the fire, this pollution further contribute to poor air quality and smog in cities such as Sao Paulo.Researchers from the University of Birmingham, the Federal University of Technology, Londrina, Brazil, and the University of Stockholm published their findings in the Professor Roy Harrison, from the University of Birmingham, commented: "The state of Sao Paulo has led with progressive measures to curb air pollution, such as controlling sulphur dioxide from industrial sources and enforcing standards for cleaner vehicles and fuels."However, present results indicate that policies targeting the reduction of biomass burning are of utmost importance to improve urban air quality, particularly in densely populated areas where high pollutant concentrations are frequently observed."Besides affecting air quality and increasing the risk of death from respiratory causes, ozone is a short-lived climate forcer -- an atmospheric compound with a warming effect but with a shorter lifetime than carbon dioxide. Reducing ozone levels has two main benefits: reducing impact on air quality and climate.Atmospheric emission data suggests that emissions from biomass burning make up a substantial part of the precursors for O3 formation.Dr. Admir Créso Targino, from the Federal University of Technology, commented: "We need enhanced governance at regional, national and international levels to combat biomass burning practices in Brazil and its neighbouring countries."Not only would the population health benefit from such a measure, but also the regional climate, as ozone and particulate matter generated by the fires are short-lived climate forcers. Such an approach would be well-aligned with the Paris Agreement that aims to limit global warming to below 2OC compared to the pre-industrial period -- a critical measure in the fight against climate change."Researchers combined in situ ozone data, measured in the states of Sao Paulo and Parana from 2014 to 2017, with information about a range of co-pollutants such as NOx, PM2.5 and PM10 to identify sources, transport and geographical patterns in the air pollution data.Ozone concentrations peaked in September and October -- linked to biomass burning and enhanced photochemistry. Long-range transport of smoke contributed to between 23 and 41 per cent of the total ozone during the pollution events.

Ozone Holes

January 13, 2020

https://www.sciencedaily.com/releases/2020/01/200113153310.htm

Iodine may slow ozone layer recovery

A new paper quantifying small levels of iodine in Earth's stratosphere could help explain why some of the planet's protective ozone layer isn't healing as fast as expected.

The paper posits a set of connections that link air pollution near Earth's surface to ozone destruction much higher in the atmosphere. That higher-level ozone protects the planet's surface from radiation that can cause skin cancer and damage crops."The impact is maybe 1.5 to 2 percent less ozone," said lead author Theodore Koenig, a postdoctoral researcher at CIRES and the University of Colorado Boulder, referring to ozone in the lower part of the ozone layer, around Earth's tropics and temperate zones. "That may sound small, but it's important," he said.A slightly thinner ozone layer means more UVB radiation can get through to Earth's surface.Koenig's paper, the first "quantitative detection" of iodine in the stratosphere, is published this week in the Chemicals once used widely in refrigeration, spray cans and solvents can eat away at Earth's ozone layer. After scientists discovered the stratospheric "ozone hole" in the 1980s, nations around the world signed the international Montreal Protocol agreement to protect the ozone layer, limiting the emission of ozone-depleting chemicals."The ozone layer is starting to show early signs of recovery in the upper stratosphere, but ozone in the lower stratosphere continues to decline for unclear reasons," said Rainer Volkamer, a CIRES Fellow, CU Boulder professor of chemistry and corresponding author of the new assessment."Before now, the decline was thought to be due to changes in how air mixes between the troposphere and stratosphere. Our measurements show there is also a chemical explanation, due to iodine from oceans. What I find exciting is that iodine changes ozone by just enough to provide a plausible explanation for why ozone in the lower stratosphere continues to decline."For the new work, Volkamer and his colleagues pored through data from several recent atmospheric research campaigns involving U.S. National Science Foundation (NSF) and NASA research aircraft, and which included instruments that could pick up tiny amounts of iodine and other so-called halogens in the lower stratosphere during the daytime. Halogens, which also include chlorine and bromine, are key to ozone destruction.It's been tricky to get data from this part of the atmosphere, Koenig said. "We knew there was some iodine there, but we couldn't pin numbers on it until now... This is a result of technological advancement: Our instruments just kept getting a little bit better and eventually, it was enough to make measurements."The amount of iodine they picked up in the lower stratosphere is tiny, similar to adding a few bottles of water to the Great Salt Lake. But iodine is extremely effective at destroying ozone, and, generally speaking, the amount the scientists measured is enough to explain the level of ozone destruction in the lower stratosphere.So where did the iodine come from? Strangely it seems to be a result of air pollution down here at the surface of the planet, the new assessment reports.Ozone at Earth's surface is a pollutant, one that is regulated in the United States and elsewhere because it can harm people's lungs. And when ozone pollution interacts chemically with the surface of oceans, it can "pull" naturally occurring iodine up into the atmosphere. Other studies have shown that in the lower atmosphere, iodine levels have roughly tripled in concentration since 1950.Some of that iodine is apparently making it up into the stratosphere, where it can trigger ozone depletion, Koenig said. "This should not diminish the success story of the Montreal Protocol, but still, it is important. The lower stratosphere should have improved already, not gotten worse.""There's something going on resulting in deterioration. Our hypothesis is that ozone at the surface is destroying ozone in the stratosphere," Koenig added.It will be important to study the hypothesis in greater detail, Koenig and his coauthors said. If ozone pollution at Earth's surface increases, for example, could it trigger even more lower-stratosphere ozone layer destruction?Coauthor Pedro Campuzano-Jost, a CIRES research associate, said the success of the research project is partly due to the unique scope of NASA's ATom (Atmospheric Tomography) mission, which flew a research aircraft across the globe; and NSF's CONTRAST (Convective Transport of Active Species in the Tropics) mission, which detected iodine oxide radicals in the stratosphere."Half of the places we went had never been sampled before for aerosols," Campuzano-Jost said, and that is the kind of opportunity that leads to new discoveries.Volkamer and his colleagues hope to successfully pitch a new mission to study iodine chemistry in greater detail, to better understand the future of Earth's protective ozone layer.

Ozone Holes

January 6, 2020

https://www.sciencedaily.com/releases/2020/01/200106141445.htm

Shutdown of coal-fired plants in US saves lives and improves crop yields

The decommissioning of coal-fired power plants in the continental United States has reduced nearby pollution and its negative impacts on human health and crop yields, according to a new University of California San Diego study.

The findings published this week in The author, Jennifer Burney, associate professor of environmental science at the UC San Diego School of Global Policy and Strategy, combined data from the Environmental Protection Agency (EPA) on electric power generation with satellite and surface measurements from the EPA as well as NASA to gauge changes in local pollution before and after coal-fired unit shut-downs. She also studied changes in county-level mortality rates and crop yields using data from the Centers for Disease Control and the U.S. Department of Agriculture.Burney found that between 2005 and 2016, the shutdown of coal-fired units saved an estimated 26,610 lives and 570 million bushels of corn, soybeans and wheat in their immediate vicinities. The inverse calculation, estimating the damages caused by coal plants left in operation over that same time period, suggests they contributed to 329,417 premature deaths and the loss of 10.2 billion bushels of crops, roughly equivalent to half of year's typical production in the U.S."The unique contribution of this study is its scope and the ability to connect discrete technology changes -- like an electric power unit being shut down -- to local health, agriculture and regional climate impacts," Burney said. "We hear a lot about the overall greenhouse gas and economic impacts of the transition the U.S. has undergone in shifting from coal towards natural gas, but the smaller-scale decisions that make up this larger trend have really important local consequences. The analysis provides a framework for communities to more thoroughly and accurately assess the costs and benefits of local investments in energy infrastructure."Burney added that although there are considerable benefits of decommissioning older coal-fired units, the newer natural gas units are not entirely benign. Natural gas units are associated with increased pollution levels; although different than the pollutant mix from coal-fired units, and more research is required to fully understand their impacts.Burney concludes that "policymakers often think about greenhouse gas emissions as a separate problem from air pollution, but the same processes that cause climate change also produce these aerosols, ozone, and other compounds that cause important damages. This study provides a more robust accounting for the full suite of emissions associated with electric power production. If we understand the real costs of things like coal better, and who is bearing those costs, it could potentially lead to more effective mitigation and formation of new coalitions of beneficiaries across sectors."

Ozone Holes

December 16, 2019

https://www.sciencedaily.com/releases/2019/12/191216132023.htm

Planetary boundaries: Interactions in Earth system amplify human impacts

What we do to one part of our Earth system does not just add to what we do to other parts: "We found a dense network of interactions between the planetary boundaries," says Johan Rockström, Director of the Potsdam Institute for Climate Impact Research and co-author of the study. Two core boundaries -- climate change and biosphere integrity -- contribute more than half the combined strengths of all the interactions in that network, the scientists find. "This highlights how careful we should be in destabilizing these two," says Rockström. "The resulting cascades and feedbacks amplify human impacts on the Earth system and thereby shrink the safe operating space for our children and grand-children."

Burning down tropical forests to expand agricultural lands for instance increases the amount of CO2 in the atmosphere. The additional greenhouse gases contribute to the global temperature increase, the harm done to the forests becomes harm to climate stability. The temperature increase can in turn further enhance stress on tropical forests, and for agriculture. The resulting amplification of effects is substantial even without taking tipping points into account: Beyond a certain threshold, the Amazon rainforest might show rapid, non-linear change. Yet such a tipping behavior would come on top of the amplification highlighted in the analysis now published.The new study builds on the groundbreaking 2009 and 2015 studies on the planetary boundaries framework that identified the nine critical systems that regulate the state of the planet: climate change, biogeochemical flows (namely of nitrogen and phosphorus), land-system change, freshwater use, aerosol loading, ozone depletion, ocean acidification, loss of biosphere integrity including biodiversity, and introductions of novel entities such as toxic chemicals and plastics. The way of staying within planetary boundaries varies from one place to another on Earth, hence calculating them and the interactions between them on an aggregated level cannot directly be translated into policies. Yet it can provide some guidance."There's good news for policy-makers in our findings," concludes Rockström. "If we reduce our pressure on one planetary boundary, this will in many cases also lessen the pressure on other planetary boundaries. Sustainable solutions amplify their effects -- this can be a real win-win."

Ozone Holes

November 18, 2019

https://www.sciencedaily.com/releases/2019/11/191118162932.htm

Nitrous oxide, a greenhouse gas, is on the rise

Most of us know nitrous oxide as "laughing gas," used for its anaesthetic effects. But nitrous oxide (N

"We see that the NIncreasing use of nitrogen fertilizers is leading to higher NIn the study, Thompson and scientists including Eric Davidson of the University of the Maryland Center for Environmental Science found that nitrous oxide in the atmosphere has risen steadily since the mid-20th century. This rise is strongly linked to an increase in nitrogen substrates released to the environment. Since the mid-20th century, the production of nitrogen fertilizers, widespread cultivation of nitrogen-fixing crops (such as clover, soybeans, alfalfa, lupins, and peanuts), and the combustion of fossil and biofuels has increased enormously the availability of nitrogen substrates in the environment."The increased nitrogen availability has made it possible to produce a lot more food," Thompson said. "The downside is of course the environmental problems associated with it, such as rising NThe study authors found that N"This new publication demonstrates both how we can solve a problem of growing greenhouse gas emissions and how current efforts are falling short in some regions of the world," said co-author Eric Davidson of the University of Maryland Center for Environmental Science. "These emissions come primarily from using fertilizers to grow food and increasing livestock herds, but we've learned how to produce more food with less nitrous oxide emission.""In Europe and North America, we have succeeded in decreasing growth in nitrous oxide emissions, an important contributor to climate change and stratospheric ozone depletion," he added. "Unfortunately, the same can't be said for Asia and South America, where fertilizer use, intensification of livestock production, and the resulting nitrous oxide emissions are growing rapidly."The good news is that this problem can be solved, but the less good news is that it will take a global effort, and we are far from there yet," he said.

Ozone Holes

October 29, 2019

https://www.sciencedaily.com/releases/2019/10/191029131458.htm

New AI deep learning model allows earlier, more accurate ozone warnings

Researchers from the University of Houston have developed an artificial intelligence-based ozone forecasting system, which would allow local areas to predict ozone levels 24 hours in advance.

That would improve health alerts for people at heightened risk of developing problems because of high ozone levels.Yunsoo Choi, associate professor in the Department of Earth and Atmospheric Sciences and corresponding author for a paper explaining the work, said they built an artificially intelligent model using a convolutional neural network, which is able to take information from current conditions and accurately predict ozone levels for the next day. The work was published in the journal "If we know the conditions of today, we can predict the conditions of tomorrow," Choi said.Ozone is an unstable gas, formed by a chemical reaction when sunlight combines with nitrogen oxides (NOx) and volatile organic compounds, both of which are found in automobile and industrial emissions. It can cause respiratory problems in people, and those especially susceptible to ozone -- including people with asthma, the elderly and young children -- are advised to reduce their exposure when ozone levels are high.Alqamah Sayeed, first author on the paper and a Ph.D. student in Choi's Air Quality Forecasting and Modeling Lab, said most current ozone forecasting models don't incorporate artificial intelligence and can take several hours to predict future ozone levels, rather than just a few seconds for the new model. They also are less accurate; the researchers reported their model correctly predicted ozone levels 24 hours in advance between 85% and 90% of the time.A key difference, Choi said, is the use of convolutional neural networks, networks capable of "sweeping" data and using that to form assumptions based on what it has learned. The convolutional networks are generally used to improve imaging resolution, he said. Choi and Sayeed said using the networks to extract information and then using artificial intelligence in order to make predictions from that data is a new application, illustrating the strength of the networks' ability to gather information and make inferences based upon that information.The researchers used meteorological and air pollution data collected at 21 stations in Houston and elsewhere in Texas by the Texas Commission on Environmental Quality, representing conditions between 2014 and 2017. Sayeed said they programmed the convolutional neural networks using meteorological data -- temperature, barometric pressure, wind speed and other variables -- for each day, and added ozone measurements from each station for 2014, 2015 and 2016.To test their belief that the model would be able to predict ozone levels given meteorological conditions from the previous day, they added weather data for 2017 and checked the forecasts the network produced for accuracy.The model's forecasts reached 90% accuracy, and Choi said it will become more accurate over time, as the network continues to learn.Although the tests were done using Texas data, the researchers said the model could be used anywhere in the world. "The U.S. is geographically different from East Asia," Choi said, "but the physics and chemistry of ozone creation are the same."Sayeed said the researchers are currently working to expand the model to include predictions of other types of pollutants, including particulate matter, as well as to extend the time period beyond 24 hours.

Ozone Holes

October 25, 2019

https://www.sciencedaily.com/releases/2019/10/191025113017.htm

Energy regulation rollbacks threaten progress against harmful ozone

Pollutants from coal-fired power plants help make ground-level ozone, and a warming world exacerbates that. Recent rollbacks of U.S. energy regulations may speed climate change, keep pollutants coming, and thus slow the fight against harmful ozone, according to a new study to be published Friday.

Currently, 30 percent of the U.S. population lives with ozone levels that exceed government health standards. Though past environmental regulations have vastly helped clean the air and put the U.S. on a positive trajectory to reduce pollutants -- including ozone -- policy rollbacks back could slow the progress then reverse it, researchers from the Georgia Institute of Technology said.Continuing progress against ozone would pay off in better health and finances: The more ozone in the air, the more cases of respiratory illness and the higher the cost of meeting ozone level targets."Additional ozone is tough to control technologically. The costs would be very high -- tens of billions of dollars," said Ted Russell, a principal investigator on the study. "In the meantime, more people would die than otherwise would have."The researchers will publish their results in The study focuses on ground-level ozone people breathe to the detriment of their health, which should not be confused with the stratospheric ozone that protects us from the sun's harmful radiation.In the last three years, various energy policies have been loosened, which should result in raised CO"Incentives are being retired like production and investment tax credits, which have been very influential in solar and wind," said Marilyn Brown, a Regents professor in Georgia Tech's School of Public Policy and a principal investigator on the study. "The Investment Tax Credit gives a 30 percent tax reduction for investments in solar or wind farms or the purchase of solar rooftop panels by homeowners. The Production Tax Credit for utilities reduces tax liabilities by 23 cents for each kilowatt-hour of electricity generated by solar, wind or other renewable energy sources."But one policy move in particular stands to keep more ingredients in the ozone-making cauldron: courts preventing the Clean Power Plan (CPP) from going into effect and its replacement with the Trump administration's Affordable Clean Energy (ACE) plan.ACE, which also has not been implemented, would make it easier to continue burning fossil fuels, particularly coal, according to Brown, who was a member of the Intergovernmental Panel on Climate Change, which received a Nobel Peace Prize in 2007. CPP would have phased out those generators, reducing nitrogen oxide gases, or NOX, key reactants in the production of ozone."The major target of the CPP was CO2, but it had side effects on the reduction of NOX because it shifted coal use to natural gas as well as to renewable sources," said Huizhong Shen, a postdoctoral researcher in Russell's group and one of the study's first authors.The study modeled atmospheric chemistry that produces O3 around commonly predicted trajectories for greenhouse gas emissions and climate change paired with anticipated pollutant emissions, particularly of NOX. The model's output depicted "non-attainment" scores, which refer to the number of U.S. counties exceeding ozone targets and by how much.The study modeled against official targets for ozone levels and in addition, against cleaner standards widely held to be attainable and much healthier for people. Models built around rolled-back environmental regulations and increased warming initially showed the current trajectory of progress against ozone levels continuing -- but later reversing. Ozone levels then rose again, putting many more counties in non-attainment by or before 2050.Alongside human-produced NOX, nature contributes ozone-making ingredients that aren't harmful per se and often smell great, like the aroma of cut grass or of a pine tree. They are examples of volatile organic compounds (VOCs), of which nature produces hundreds.VOCs get into the air easily and react readily with other chemicals. The warmer the air and the sun, the more vegetation produces VOCs that meet with raised levels of NOX emissions to make ozone. It forms downstream from emissions sources, making it hard to regulate."There are no ozone emissions, just precursor emissions," Shen said. "So, emission controls for ozone have to mainly target NOX emissions."Keeping ozone around as the world warms will be more than just the sum of power plants still emitting NOX plus boosted VOC emissions."If you heat up the air, it also speeds up photochemical reactions involved in ozone production," Shen said."Ozone is a greenhouse gas, so it adds some climate change feedback, too," said Russell, who is Howard T. Tellepsen Chair and Regents Professor in Georgia Tech's School of Civil and Environmental Engineering. "You can also have increased vegetation emissions of ammonia. Some of this goes on to form particulate matter, which is also harmful to the lungs."When coal-fired power plants emit NOX, the ozone strikes miles away."Ozone can occur hundreds of miles away, so if controls are loosened in one state to save industry money there, a state downstream may have to spend even more to try to meet ozone targets. You transfer the problem and the costs," Russell said. "Most U.S. cities are already not in attainment, and this will likely make it harder for them to get there."The research was funded by the U.S. Environmental Protection Agency and by the National Science Foundation.

Ozone Holes

October 3, 2019

https://www.sciencedaily.com/releases/2019/10/191003162541.htm

How much are you polluting your office air just by existing?

Just by breathing or wearing deodorant, you have more influence over your office space than you might think, a growing body of evidence shows. But could these basic acts of existence also be polluting the air in the office room where you work?

To find out, a team of engineers at Purdue University has been conducting one of the largest studies of its kind in the office spaces of a building rigged with thousands of sensors. The goal is to identify all types of indoor air contaminants and recommend ways to control them through how a building is designed and operated."If we want to provide better air quality for office workers to improve their productivity, it is important to first understand what's in the air and what factors influence the emissions and removal of pollutants," said Brandon Boor, an assistant professor of civil engineering with a courtesy appointment in environmental and ecological engineering.The data is showing that people and ventilation systems greatly impact the chemistry of indoor air -- possibly more than anything else in an office space. The researchers will present their initial findings at the 2019 American Association for Aerosol Research Conference in Portland, Oregon, Oct. 14-18."The chemistry of indoor air is dynamic. It changes throughout the day based on outdoor conditions, how the ventilation system operates and occupancy patterns in the office," Boor said.The building, called the Living Labs at Purdue's Ray W. Herrick Laboratories, uses an array of sensors to precisely monitor four open-plan office spaces and to track the flow of indoor and outdoor air through the ventilation system. The team developed a new technique to track occupancy by embedding temperature sensors in each desk chair.Through use of the Living Labs, Boor's team has begun to identify previously unknown behaviors of chemicals called volatile organic compounds, such as how they are transformed in ventilation systems and removed by filters."We wanted to shed light on the behind-the-scenes role ventilation systems have on the air we breathe," Boor said.Boor teamed up with researchers at RJ Lee Group to deploy a highly sensitive "nose" -- an instrument that scientists call a proton transfer reaction time-of-flight mass spectrometer. The instrument, typically used for measuring outdoor air quality, helped "sniff" out compounds in human breath, such as isoprene, in real time. Boor's team found that isoprene and many other volatile compounds linger in the office even after people have left the room.A greater number of people in a room also means more emissions of these compounds. A YouTube video is available at "Our preliminary results suggest that people are the dominant source of volatile organic compounds in a modern office environment," Boor said. "We found levels of many compounds to be 10 to 20 times higher indoors than outdoors. If an office space is not properly ventilated, these volatile compounds may adversely affect worker health and productivity."The team also revealed that a pollutant entering from outside, ozone, disappears inside. This is because ozone interacts with other indoor compounds and the vast surfaces of a furnished office. The researchers found that ozone and compounds released from peeling an orange, called monoterpenes, mix to form new, super-tiny particles as small as one-billionth of a meter. The newly formed particles could be toxic because they are small enough to get into the deepest regions of a person's lungs.The effects of volatile compounds released in an office might not just be restricted to indoors. The researchers believe that chemicals emitted from self-care products such as deodorant, makeup, and hair spray may elevate levels outdoors as they are vented outside by the ventilation system.This work is funded in part by the National Science Foundation Environmental Engineering Program, the Alfred P. Sloan Foundation Chemistry of Indoor Environments Program and the Purdue Research Foundation.

Ozone Holes

October 1, 2019

https://www.sciencedaily.com/releases/2019/10/191001083959.htm

Rising ozone is a hidden threat to corn

Like atmospheric methane and carbon dioxide, ground-level ozone is on the rise. But ozone, a noxious chemical byproduct of fossil fuel combustion, has received relatively little attention as a potential threat to corn agriculture.

A new study begins to address this lapse by exposing a genetically diverse group of corn plants in the field to future ozone levels. The study, reported in the journal "Ozone enters plants the same way carbon dioxide does: It diffuses from the atmosphere into the leaf," said Lisa Ainsworth, a U.S. Department of Agriculture scientist who led the research with University of Illinois plant biology professor Andrew Leakey; University of Florida molecular genetics and microbiology professor Lauren McIntyre; and University of California, Davis plant sciences professor Patrick Brown. Ainsworth and Leakey are affiliates of the Carl R. Woese Institute for Genomic Biology and the department of crop sciences at Illinois.Carbon dioxide is a nutrient for plants, Ainsworth said. "All the carbon that ends up in the grain comes through the leaf first," she said. But ozone is a highly reactive molecule that damages biological tissues and impairs photosynthetic carbon capture in plant leaves."Basically, ozone accelerates the aging of the leaf," Leakey said.Even background levels of ozone do some damage, Ainsworth said. "Our research suggests that current ozone levels decrease corn yields by as much as 10%," she said. "That's as much as drought or flooding or any single pest or disease, but this is a relatively unstudied component of yield loss in the U.S."The researchers used the Free Air Concentration Enrichment facility at the U. of I. to track the real-world consequences of higher atmospheric ozone levels in an agricultural field. The FACE facility uses a sophisticated emission system that monitors wind direction and speed to dose a field with specific levels of a variety of gases, including ozone."The level that we're fumigating to in this study is a level that is commonly found today in China and India," Ainsworth said. "So, it's not excessively high, even though we're using a concentration that is 2 1/2 times the level of background ozone in central Illinois."The researchers planted 45 hybrid corn plants representing all the major types of corn -- popcorn, broom corn, dent, flint and others -- to look for variation in their responses to high ozone levels. They found that some hybrids were more sensitive to ozone stress than others."We found two maize lines whose offspring were more sensitive to ozone pollution, regardless of which other types of corn we bred them with," Leakey said. "Their genetic deficiencies manifested in different ways when exposed to the high ozone conditions."The genetics of commercial corn are a trade secret, so "we don't know if these corn varieties have the same Achilles' heels," Leakey said. "Breeders would not know about these differences since they are not apparent under clean-air conditions."More genetic analysis and more experiments like those conducted at the FACE facility will be needed to determine how today's plants will respond to future conditions, Leakey said."It's important to understand how plants are going to respond to climate change before the climate changes," he said. "That is the only way we can find the solutions that will be needed in the future."

Ozone Holes

September 18, 2019

https://www.sciencedaily.com/releases/2019/09/190918100230.htm

Emissions from cannabis growing facilities may impact indoor and regional air quality

The same chemicals responsible for the pungent smell of a cannabis plant may also contribute to air pollution on a much larger scale, according to new research from the Desert Research Institute (DRI) and the Washoe County Health District (WCHD) in Reno, Nev.

In a new pilot study, DRI scientists visited four cannabis growing facilities in Nevada and California to learn about the chemicals that are emitted during the cultivation and processing of cannabis plants, and to evaluate the potential for larger-scale impacts to urban air quality.At each facility, the team found high levels of strongly-scented airborne chemicals called biogenic volatile organic compounds (BVOCs), which are naturally produced by the cannabis plants during growth and reproduction. At facilities where cannabis oil extraction took place, researchers also found very high levels of butane, a volatile organic compound (VOC) that is used during the oil extraction process."The concentrations of BVOCs and butane that we measured inside of these facilities were high enough to be concerning," explained lead author Vera Samburova, Ph.D., Associate Research Professor of atmospheric science at DRI. "In addition to being potentially hazardous to the workers inside the cannabis growing and processing facilities, these chemicals can contribute to the formation of ground-level ozone if they are released into the outside air."Although ozone in the upper atmosphere provides protection from UV rays, ozone at ground-level is a toxic substance that is harmful for humans to breathe. Ozone can be formed when volatile organic compounds (including those from plants, automobile, and industrial sources) combine with nitrogen oxide emissions (often from vehicles or fuel combustion) in the presence of sunlight. All of these ozone ingredients are in ample supply in Nevada's urban areas, Samburova explained -- and that impacts our air quality."Here in our region, unfortunately, we already exceed the national air quality standard for ground-level ozone quite a few times per year," Samburova said. "That's why it is so important to answer the question of whether emissions from cannabis facilities are having an added impact."At one of the four cannabis growing facilities visited during this study, the team measured emission rates over time, to learn about the ozone-forming potential of each individual plant. The results show that the BVOCs emitted by each cannabis plant could trigger the formation of ground-level (bad) ozone at a rate of approximately 2.6g per plant per day. The significance of this number is yet to be determined, says Samurova, but she and her team feel strongly that their findings have raised questions that warrant further study."This really hasn't been studied before," Samburova said. "We would like to collect more data on emissions rates of plants at additional facilities. We would like to take more detailed measurements of air quality emissions outside of the facilities, and be able to calculate the actual rate of ozone formation. We are also interested in learning about the health impacts of these emissions on the people who work there."The cannabis facility personnel that the DRI research team interacted with during the course of the study were all extremely welcoming, helpful, and interested in doing things right, Samburova noted. Next, she and her team hope to find funding to do a larger study, so that they can provide recommendations to the growing facilities and WCHD on optimum strategies for air pollution control."With so much growth in this industry across Nevada and other parts of the United States, it's becoming really important to understand the impacts to air quality," said Mike Wolf, Permitting and Enforcement Branch Chief for the WCHD Air Quality Management Division. "When new threats emerge, our mission remains the same: Implement clean air solutions that protect the quality of life for the citizens of Reno, Sparks, and Washoe County. We will continue to work with community partners, like DRI, to accomplish the mission."

Ozone Holes

August 28, 2019

https://www.sciencedaily.com/releases/2019/08/190828140132.htm

Earth's fingerprint hints at finding habitable planets beyond the solar system

Two McGill University astronomers have assembled a "fingerprint" for Earth, which could be used to identify a planet beyond our Solar System capable of supporting life.

McGill Physics student Evelyn Macdonald and her supervisor Prof. Nicolas Cowan used over a decade of observations of Earth's atmosphere taken by the SCISAT satellite to construct a transit spectrum of Earth, a sort of fingerprint for Earth's atmosphere in infrared light, which shows the presence of key molecules in the search for habitable worlds. This includes the simultaneous presence of ozone and methane, which scientists expect to see only when there is an organic source of these compounds on the planet. Such a detection is called a "biosignature.""A handful of researchers have tried to simulate Earth's transit spectrum, but this is the first empirical infrared transit spectrum of Earth," says Prof. Cowan. "This is what alien astronomers would see if they observed a transit of Earth."The findings, published Aug. 28 in the journal Cowan was explaining transit spectroscopy of exoplanets at a group lunch meeting at the McGill Space Institute (MSI) when Prof. Yi Huang, an atmospheric scientist and fellow member of the MSI, noted that the technique was similar to solar occultation studies of Earth's atmosphere, as done by SCISAT.Since the first discovery of an exoplanet in the 1990s, astronomers have confirmed the existence of 4,000 exoplanets. The holy grail in this relatively new field of astronomy is to find planets that could potentially host life -- an Earth 2.0.A very promising system that might hold such planets, called TRAPPIST-1, will be a target for the upcoming James Webb Space Telescope, set to launch in 2021. Macdonald and Cowan built a simulated signal of what an Earth-like planet's atmosphere would look like through the eyes of this future telescope which is a collaboration between NASA, the Canadian Space Agency and the European Space Agency.The TRAPPIST-1 system located 40 light years away contains seven planets, three or four of which are in the so-called "habitable zone" where liquid water could exist. The McGill astronomers say this system might be a promising place to search for a signal similar to their Earth fingerprint since the planets are orbiting an M-dwarf star, a type of star which is smaller and colder than our Sun."TRAPPIST-1 is a nearby red dwarf star, which makes its planets excellent targets for transit spectroscopy. This is because the star is much smaller than the Sun, so its planets are relatively easy to observe," explains Macdonald. "Also, these planets orbit close to the star, so they transit every few days. Of course, even if one of the planets harbours life, we don't expect its atmosphere to be identical to Earth's since the star is so different from the Sun."According to their analysis, Macdonald and Cowan affirm that the Webb Telescope will be sensitive enough to detect carbon dioxide and water vapour using its instruments. It may even be able to detect the biosignature of methane and ozone if enough time is spent observing the target planet.Prof. Cowan and his colleagues at the Montreal-based Institute for Research on Exoplanets are hoping to be some of the first to detect signs of life beyond our home planet. The fingerprint of Earth assembled by Macdonald for her senior undergraduate thesis could tell other astronomers what to look for in this search. She will be starting her Ph.D. in the field of exoplanets at the University of Toronto in the Fall.

Ozone Holes

August 13, 2019

https://www.sciencedaily.com/releases/2019/08/190813180833.htm

Air pollution can accelerate lung disease as much as a pack a day of cigarettes

Air pollution -- especially ozone air pollution which is increasing with climate change -- accelerates the progression of emphysema of the lung, according to a new study led by the University of Washington, Columbia University and the University at Buffalo.

While previous studies have shown a clear connection of air pollutants with some heart and lung diseases, the new research published Aug. 13 in "We were surprised to see how strong air pollution's impact was on the progression of emphysema on lung scans, in the same league as the effects of cigarette smoking, which is by far the best-known cause of emphysema," said the study's senior co-author, Dr. Joel Kaufman, UW professor of environmental and occupational health sciences and epidemiology in the School of Public Health.In fact, the researchers found, if the ambient ozone level was 3 parts per billion higher where you live compared to another location over 10 years, that was associated with an increase in emphysema roughly the equivalent of smoking a pack of cigarettes a day for 29 years. And the study determined that ozone levels in some major U.S. cities are increasing by that amount, due in part to climate change. The annual averages of ozone levels in study areas were between about 10 and 25 ppb."Rates of chronic lung disease in this country are going up and increasingly it is recognized that this disease occurs in nonsmokers," said Kaufman, also a professor of internal medicine and a physician at UW School of Medicine. "We really need to understand what's causing chronic lung disease, and it appears that air pollution exposures that are common and hard to avoid might be a major contributor."The results are based on an extensive, 18-year study involving more than 7,000 people and a detailed examination of the air pollution they encountered between 2000 and 2018 in six metropolitan regions across the U.S.: Chicago, Winston-Salem, N.C., Baltimore, Los Angeles, St. Paul, Minnesota, and New York. The participants were drawn from the Multi-Ethnic Study of Atherosclerosis (MESA) Air and Lung studies."To our knowledge, this is the first longitudinal study to assess the association between long-term exposure to air pollutants and progression of percent emphysema in a large, community-based, multi-ethnic cohort," said first author Meng Wang, an assistant professor of epidemiology and environmental health at the University at Buffalo who conducted the research as a postdoctoral researcher at the UW.The authors developed novel and accurate exposure assessment methods for air pollution levels at the homes of study participants, collecting detailed measurement of exposures over years in these metropolitan regions, and measurements at the homes of many of the participants. This work in the MESA Air study was led at the University of Washington. While most of the airborne pollutants are in decline because of successful efforts to reduce them, ozone has been increasing, the study found. Ground-level ozone is mostly produced when ultraviolet light reacts with pollutants from fossil fuels."This is a big study with state-of-the-art analysis of more than 15,000 CT scans repeated on thousands of people over as long as 18 years. These findings matter since ground-level ozone levels are rising, and the amount of emphysema on CT scans predicts hospitalization from and deaths due to chronic lung disease," said Dr. R. Graham Barr, professor of medicine and epidemiology at Columbia University who led the MESA Lung study and is a senior author of the paper."As temperatures rise with climate change," Barr explained, "ground-level ozone will continue to increase unless steps are taken to reduce this pollutant. But it's not clear what level of the air pollutants, if any, is safe for human health."Emphysema was measured from CT scans that identify holes in the small air sacs of the participants' lungs, and lung function tests, which measure the speed and amount of air breathed in and out."This study adds to growing evidence of a link between air pollution and emphysema. A better understanding of the impact of pollutants on the lung could lead to more effective ways of preventing and treating this devastating disease," said James Kiley, director of the Division of Lung Diseases at the National Heart, Lung, and Blood Institute, part of the National Institutes of Health."It's important that we continue to explore factors that impact emphysema," Kiley added, "particularly in a large, well-characterized multi-ethnic group of adults such as those represented by MESA."

Ozone Holes

July 25, 2019

https://www.sciencedaily.com/releases/2019/07/190725100519.htm

Reducing greenhouse gas in rocky mountain region has health, financial benefits

Research by Drexel University and the University of Colorado at Boulder suggests that imposing fees on energy producers that emit greenhouse gas could improve the health and financial well-being of the Rocky Mountain region.

Using sophisticated modeling programs that can project atmospheric concentrations of ozone, a ground-level pollutant, by considering factors like current emissions from power plants, weather trends and changes in energy production, the team compared the effects of four scenarios on the Rocky Mountain region of 2030. Their findings were recently published in the journal Looking closely at coal, oil and natural gas production regions in Colorado, Utah, Wyoming and northern New Mexico -- a region in the midst of planning its energy production transition over the next several decades -- the team proposed four energy production policy scenarios, any of which could very well be in effect by 2030."Opportunities to produce power through newly accessible oil and gas as well as renewable resources have increased rapidly in the Rocky Mountain region, which has a growing population," said Shannon Capps, PhD, an assistant professor in Drexel's College of Engineering who helped conduct the research. "The region needs more electricity and has choices about how to produce it. This analysis helps people understand the implications of different choices, some imbedded in infrastructure that will shape climate and air quality in lasting ways."The first is a baseline scenario in which current transitions away from coal energy and toward natural gas, including the planned closing of several coal plants and the creation of new natural gas extraction sites, are taken into consideration.Two scenarios consider the effects of changes in the cost of energy production from natural gas -- either that it will be more expensive to produce than coal or that it will continue to be less expensive.The final scenario considers the possibility of fees being imposed on the producers of greenhouse gas -- a policy that has been proposed by the previous administration's Clean Power Plan and proponents of the Green New Deal.The group used recent results from energy grid modeling under the different scenarios to calculate realistic emissions of greenhouse gases -- carbon dioxide and methane -, sulfur dioxide, nitrogen oxides, volatile organic compounds (VOCs) for atmospheric modeling programs that determine the associated amount of ozone. The team then employed a tool created by the Environmental Protection Agency to determine how the ozone in each scenario would affect the health of people in the region and also calculated the social costs of the associated greenhouse gas emissions.Their research predicts that in all scenarios, other than the one in which natural gas production becomes less costly, greenhouse gas emissions would be reduced following the closure of plants -- whether by planned retirement -- in the 2030 baseline scenario -- or as a cost-saving measure -- in the "expensive gas" and "greenhouse gas fees" scenarios.While this might not be a surprising finding at this point in our collective understanding of energy production and sustainability, the health and financial ripple effects of these changes are stark, according to the research."The reduction in ozone from 2011 to the 2030 baseline scenario is estimated to reduce total mortalities (sum of short-term and long-term mortalities) by about 200 annual deaths," according to the study.Metrics that associate an economic impact with mortality rate calculate that the health benefits of this scenario would equate to $2 billion.Mortality rates continue to improve under a scenario where fees are imposed on producers of greenhouse gas, along with an additional economic benefit of $200 million.Conversely, if gas prices were to fall -- resulting in greater use of it, and increased emissions -- the model predicts a spike in mortality rate that correlates to an $80 million reduction in the economic gains expected by 2030.The study highlights the difficult decisions facing policymakers when it comes to sourcing energy. For example, while shifting away from coal consumption toward natural gas and oil reduces carbon dioxide emissions, those benefits are offset by an increase in methane, sulfur dioxide and VOCs associated with the extraction and use of those sources.A policy that puts fees on greenhouse gas-emitting energy producers could be met with opposition, but it could also drive market forces toward greater use of energy from renewable sources like wind and solar, which are abundant in the region -- with the co-benefit of reducing emissions from gas and oil operations."This type of research continues to be important as other regions in the U.S. and abroad have access to similar technology for oil and gas extraction, as well as renewable energy production. The outcomes of this study ought to drive careful consideration of those choices," Capps said.In addition to Capps, this research was conducted by Rene Nzanzineza and Jana B. Milford from the University of Colorado at Boulder. It was supported by the National Science Foundation.

Ozone Holes

July 23, 2019

https://www.sciencedaily.com/releases/2019/07/190723121906.htm

Ozone threat from climate change

Increasing temperatures due to climate change will shift climatic conditions, resulting in worse air quality by increasing the number of days with high concentrations of ozone, according to a new journal article on air quality throughout the Mid-Atlantic region from researchers at the University of Delaware's College of Earth, Ocean and Environment(CEOE).

Cristina Archer led a team from CEOE as the members compiled nearly 50 years' worth of data from Delaware Department of Natural Resources and Environmental Control (DNREC) air monitoring and climate models to analyze climatic trends. They found that rising temperatures will increase the number of days in a year where ozone levels in Earth's lower atmosphere become dangerous.Archer said DNREC, which funded her study, is concerned with near-ground ozone levels for two main reasons: impacts on human health and compliance with federal and state regulations limiting high-ozone concentrations."Ozone has large negative impacts on health, especially affecting the cardiopulmonary and respiratory systems," Archer said. "It is especially bad if you already have a respiratory condition, asthma, for example, or an infection. In Delaware, we are barely in attainment or slightly in non-attainment (of ozone regulations). When we are not in attainment, the Environmental Protection Agency has to act. That is the relevance. That is why we need to know now there is a problem, so we can act on it."The study, titled "Global Warming Will Aggravate Ozone Pollution in the U.S. Mid-Atlantic," was recently published in the Archer is a professor in CEOE with a joint appointment between the Physical Ocean Science and Engineering (POSE) program of the School of Marine Science and Policy and the Department of Geography. Collaborators in the research and writing were Sara Rauscher, an associate professor in the Department of Geography, and Joseph Brodie, a former graduate student and postdoctoral researcher at CEOE who is currently director of atmospheric research at the Rutgers University Center for Ocean Observing Leadership.Ozone in the upper atmosphere is beneficial for blocking harmful ultraviolet (UV) rays from the sun. However, ozone closer to the surface of the Earth -- the focus of the study -- can lead to pulmonary complications among the population. Near-ground ozone can lead to coughing, irritation of the throat and chest, exacerbation of asthma, inflammation of lung cells, aggravation of chronic lung diseases, and ozone even reduces the disease-fighting capabilities of the immune system. On days where ozone levels are high enough, prolonged exposure can even lead to permanent lung damage. Ozone is regulated as a pollutant by the EPA because of ozone's hazardous nature.Near-ground ozone forms as a result of photochemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs). Intense UV rays from the sun are the catalyst for the reactions between NOx emissions and the VOCs. NOx emissions occur when cars or power plants burn fossil fuels such as coal and gasoline. VOCs are also human-made and derive from a variety of sources, including cars and gasoline-burning engines, paints, insecticides, cleaners, industrial solvents, and chemical manufacturing.According to Archer, limiting ozone is difficult because it is a secondary pollutant."There are primary pollutants that are emitted and there are secondary pollutants that form in the air," said Archer. "Ozone is one of these [secondary pollutants]. You can't go to a smokestack and measure the ozone coming out. You'll get precursors or other compounds that form it but never ozone itself."Most of the time, near-ground ozone is not an issue for Delaware. As outlined in Archer's paper, during the 1980s the average number of high-ozone days in Delaware was about 75, whereas by 2015 it was less than 20, decreasing by about two days every year due to stricter air quality regulations.However, the team of researchers found that increasing temperatures due to climate change are threatening to reverse the decrease in near-ground ozone pollution and increase the number of days where surface ozone levels become dangerous.Conditions that lead to high-ozone days are typical of hot summer days.As global temperatures increase, summers will continue to get hotter and will lead to more days with high ozone concentrations. Archer also stated that more high-ozone days could also occur during the fall and spring, since increasing global temperatures will make those seasons warmer on average. According to the Intergovernmental Panel for Climate Change, global temperatures have increased by one degree Celsius as of 2019 and will increase by another one degree Celsius by the end of the 21st century. Archer also said high-ozone days themselves may become more intense due to increased ozone concentrations.The increase in the number and intensity of high-ozone days is troubling because the adverse health effects impact anyone who spends ample time outdoors, including children and people who exercise outside. More people go outside more often during the summer, potentially increasing human exposure to dangerous levels of near-ground ozone.In the article, Archer said that a "business as usual" approach will inevitably lead to a dangerous increase in high-ozone days. Archer said that the country needs stricter regulations if it is to limit the number of high-ozone days.

Ozone Holes

July 22, 2019

https://www.sciencedaily.com/releases/2019/07/190722115931.htm

Airborne lidar system poised to improve accuracy of climate change models

Researchers have developed a laser-based system that can be used for airborne measurement of important atmospheric gases with unprecedented accuracy and resolution. The ability to collect this data will help scientists better understand how these atmospheric gases affect the climate and could help improve climate change predictions.

In the Optical Society journal The tropopause separates the surface-based troposphere layer where weather takes place from the overlying stratosphere that contains the ozone layer that protects life on Earth from harmful radiation. Scientists want to study water vapor and ozone in the tropopause because the distribution of these atmospheric gases in this layer plays a crucial role in the Earth's climate."The ability to detect the vertical structure of water vapor and ozone is critical for understanding the exchange of these atmospheric gases between the troposphere and the stratosphere," said Andreas Fix, who led the research team. "These measurements could help us identify errors and uncertainties in climate models that would help improve predictions of the future climate, which is one of the central challenges for our society and economy."Atmospheric gases can be assessed with instruments flown into the atmosphere or with data acquired from satellites. However, these methods haven't been able to provide a full picture of atmospheric gas distribution because they either lack the vertical component or don't provide high enough resolution. Although instruments carried with balloons -- known as balloon sondes -- can provide highly resolved vertical profiles they don't offer detailed temporal resolution and can only be used at selected sites.To solve these problems, the researchers developed a lidar system that uses laser light to measure both ozone and water vapor at the same time. Their approach, called differential absorption lidar (DIAL), uses two slightly different UV wavelengths to measure each gas. The UV radiation at one wavelength is mostly absorbed by the gas molecules while most of the other wavelength is reflected. Measuring the ratio of the UV signals returning from the atmosphere allows calculation of a detailed gas profile.The gas profiles created using the new lidar system exhibit a vertical resolution of around 250 meters and a horizontal resolution of about 10 kilometers below the aircraft's flight track."This vertical capability is a significant advancement in studying exchange processes at the tropopause," said Fix. "It helps overcome significant shortcomings in resolving the fine-scale distribution that have made it difficult to understand processes responsible for exchange at the tropopause."To perform this method aboard a plane, the researchers used a highly efficient optical parametric oscillator (OPO) they previously developed to convert the laser output to the UV wavelengths needed to measure water vapor and ozone. "The conversion needs to be very energy efficient to generate UV radiation with adequate pulse energies and high average power from the limited energy available on board an aircraft," explained Fix.Tests of the new lidar system showed that its accuracy matched well with that of balloon sondes. In 2017, the researchers flew the new system aboard the wave-driven isentropic exchange (WISE) mission, which involved multiple long-range flights over the North Atlantic and Northern Europe. They found that the instrument worked remarkably well, remained stable during use and could measure characteristic ozone and water vapor distributions at the tropopause.The researchers plan to analyze the new vertical-component data acquired during WISE and integrate it into climate models. They expect to use the instrument to collect data atmospheric gas information aboard future flights.

Ozone Holes

July 16, 2019

https://www.sciencedaily.com/releases/2019/07/190716151358.htm

By cutting ozone pollution now, China could save 330,000 lives by 2050

If China takes strong measures to reduce its ozone pollution now, it could save hundreds of thousands of lives in the long run, according to a new study led by researchers at Columbia University's Lamont-Doherty Earth Observatory.

"Air pollution is a major problem in China right now," said lead author Daniel Westervelt, an associate research scientist at Lamont-Doherty. "It's a very serious health risk. So it's important to think about what changes can be made to make progress on this problem."High up in the atmosphere, the ozone layer protects our planet from harsh ultraviolet radiation. But when ozone gets into the air we breathe, it can lead to premature death from cardiovascular disease, stroke and respiratory problems. On-the-ground ozone pollution is created when other pollutants -- nitrogen oxides and volatile organic compounds -- react together with sunlight. Those pollutants can come from motor vehicles, power plants, factories and other human-made sources.Ozone pollution is already dangerously common in China, causing an estimated 67,000 premature deaths in 2015. But the new study, published today in The first scenario looked at what would happen if China's air pollution levels stay fixed but the climate continues to warm. The second scenario looked at the effects of climate change plus a 10 percent increase in ozone pollution emissions -- representing a 'status quo' strategy, according to Westervelt. And the third scenario analyzed the impacts of climate change plus an aggressive approach of cutting China's ozone-forming emissions by 60 percent.Plugging those scenarios into a model of atmospheric chemistry and climate, the team found that climate change alone could cause a 11 percent increase in ozone pollution in China. This would cause an additional 62,000 premature deaths by 2050.In the second scenario, a 10 percent increase in emissions of air pollutants combined with climate change caused an additional 80,000 premature deaths. On the other hand, a 60 percent decrease in ozone-forming emissions prevented 330,000 premature deaths.In all three simulations, climate change made ozone pollution worse than it would have been otherwise. That wasn't surprising; scientists know that warmer temperatures will speed up the reactions that create ozone and enhance conditions that allow it to accumulate near the surface. However, the study revealed another startling way that climate change could exacerbate ozone pollution: "It turns out that a major portion of the ozone increase we're seeing in the model in western China originates in the stratosphere," said Westervelt.It's normal for some ozone to trickle down from the ozone layer to the ground, but the model showed that by changing the jetstream and mixing patterns of the atmosphere, climate change could enhance the flow of ozone from the stratosphere to the surface, particularly over western China and the Tibetan plateau.The team also calculated that emissions from other countries, including India, could significantly detract from China's air quality gains if it does decide to reduce emissions. The authors write that China would benefit by encouraging emissions reductions throughout all of Asia. "If China is able to be a leader on this and say, 'We need to reduce our emissions,' other countries may follow suit," Westervelt suggested.The study shows that China is at an important crossroads, with its future air quality depending strongly on passing policies to reduce both ozone- and climate change-causing emissions, said Westervelt. "The issues of climate change and air quality go hand-in-hand, so it makes sense to tackle both things simultaneously."To be sure, cutting ozone-causing emissions by 60 percent wouldn't come easy. It would require many new policies to fall into place, such as increasing fuel efficiency standards, switching to electric vehicles, installing air pollution control devices on power plant smokestacks, and switching to cleaner sources of energy, such as natural gas and renewables. Nevertheless, the 60 percent reduction is feasible based on policy measures and technologies that already exist today, said Westervelt."I would hope that policymakers in China will take results like this and see that if you were to aggressively reduce emissions, you would reap the benefits in a pretty significant way," he said. "It's worth it to address these emissions now, so that you don't have to deal with all the health problems in the future. You could save 330,000 over the next few decades. That's a lot of lives."Other authors on the paper included: Arlene Fiore, Mike He, Marianthi-Anna Kioumourtzoglou, and Gustavo Correa from Columbia University; Clara Ma from Yale University; Patrick Kinney from Boston University; and Shuxiao Wang, Jia Xing, and Dian Ding of Tsinghua University.

Ozone Holes

June 28, 2019

https://www.sciencedaily.com/releases/2019/06/190628120533.htm

Pig-Pen effect: Mixing skin oil and ozone can produce a personal pollution cloud

When ozone and skin oils meet, the resulting reaction may help remove ozone from an indoor environment, but it can also produce a personal cloud of pollutants that affects indoor air quality, according to a team of researchers.

In a computer model of indoor environments, the researchers show that a range of volatile and semi-volatile gases and substances are produced when ozone, a form of oxygen that can be toxic, reacts with skin oils carried by soiled clothes, a reaction that some researchers have likened to the less-than-tidy Peanuts comic strip character."When the ozone is depleted through human skin, we become the generator of the primary products, which can cause sensory irritations," said Donghyun Rim, assistant professor of architectural engineering and an Institute for CyberScience associate, Penn State. "Some people call this higher concentration of pollutants around the human body the personal cloud, or we call it the 'Pig-Pen Effect.'"The substances that are produced by the reaction include organic compounds, such as carbonyls, that can irritate the skin and lungs, said Rim. People with asthma may be particularly vulnerable to ozone and ozone reaction products, he said.According to the researchers, who reported their findings in a recent issue of Nature's "Squalene can react very effectively with ozone," said Rim. "Squalene has a higher reaction rate with ozone because it has a double carbon bond and, because of its chemical makeup, the ozone wants to jump in and break this bond."Indoors, ozone concentration can range from 5 to 25 parts per billion -- ppb -- depending on how the air is circulating from outside to inside and what types of chemicals and surfaces are used in the building. In a polluted city, for example, the amount of ozone in indoor environments may be much higher."A lot of people think of the ozone layer when we talk about ozone," said Rim. "But, we're not talking about that ozone, that's good ozone. But ozone at the ground level has adverse health impacts."Wearing clean clothes might be a good idea for a lot of reasons, but it might not necessarily lead to reducing exposure to ozone, said Rim. For example, a single soiled t-shirt helps keep ozone out of the breathing zone by removing about 30 to 70 percent of the ozone circulating near a person."If you have clean clothes, that means you might be breathing in more of this ozone, which isn't good for you either," said Rim.Rim said that the research is one part of a larger project to better understand the indoor environment where people spend most of their time."The bottom line is that we, humans, spend more than 90 percent of our time in buildings, or indoor environments, but, as far as actual research goes, there are still a lot of unknowns about what's going on and what types of gases and particles we're exposed to in indoor environments," said Rim. "The things that we inhale, that we touch, that we interact with, many of those things are contributing to the chemical accumulations in our body and our health."Rather than advising people whether to wear clean or dirty clothes, the researchers suggest that people should focus on keeping ground ozone levels down. Better building design and filtration, along with cutting pollution, are ways that could cut the impact of the Pig-Pen Effect, they added.To build and validate the models, the researchers used experimental data from prior experiments investigating reactions between ozone and squalene, and between ozone and clothing. The researchers then analyzed further how the squalene-ozone reaction creates pollutants in various indoor conditions.The team relied on computer modeling to simulate indoor spaces that vary with ventilation conditions and how inhabitants of those spaces manage air quality, Rim said.In the future, the team may look at how other common indoor sources, such as candle and cigarette smoke, could affect the indoor air quality and its impact on human health.

Ozone Holes

June 24, 2019

https://www.sciencedaily.com/releases/2019/06/190624111536.htm

Damage to the ozone layer and climate change forming feedback loop

Increased solar radiation penetrating through the damaged ozone layer is interacting with the changing climate, and the consequences are rippling through the Earth's natural systems, effecting everything from weather to the health and abundance of sea mammals like seals and penguins. These findings were detailed in a review article published today in

"What we're seeing is that ozone changes have shifted temperature and precipitation patterns in the southern hemisphere, and that's altering where the algae in the ocean are, which is altering where the fish are, and where the walruses and seals are, so we're seeing many changes in the food web," said Kevin Rose, a researcher at Rensselaer Polytechnic Institute who serves on the panel and is a co-author of the review article.The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer -- the first multilateral environmental agreement to be ratified by all member nations of the United Nations -- was designed to protect Earth's main filter for solar ultraviolet radiation by phasing out production of harmful humanmade substances, such as the chlorofluorocarbons class of refrigerants. The treaty has largely been considered a success, with global mean total ozone projected to recover to pre-1980 levels by the middle of the 21st century. Earlier this year, however, researchers reported detecting new emissions of ozone depleting substances emanating from East Asia, which could threaten ozone recovery.While ozone depletion has long been known to increase harmful UV radiation at the Earth's surface, its effect on climate has only recently become evident. The report points to the Southern Hemisphere, where a hole in the ozone layer above Antarctica has pushed the Antarctic Oscillation -- the north-south movement of a wind belt that circles the Southern Hemisphere -- further south than it has been in roughly a thousand years. The movement of the Antarctic Oscillation is in turn directly contributing to climate change in the Southern Hemisphere.As climate zones have shifted southward, rainfall patterns, sea-surface temperatures, and ocean currents across large areas of the southern hemisphere have also shifted, impacting terrestrial and aquatic ecosystems. The effects can be seen in Australia, New Zealand, Antarctica, South America, Africa, and the Southern Ocean.In the oceans, for example, some areas have become cooler and more productive, where other areas have become warmer and less productive.Warmer oceans are linked to declines in Tasmanian kelp beds and Brazilian coral reefs, and the ecosystems that rely on them. Cooler waters have benefitted some populations of penguins, seabirds, and seals, who profit from greater populations of krill and fish. One study reported that female albatrosses may have become a kilogram heavier in certain areas because of the more productive cooler waters linked to ozone depletion.Rose also pointed to subtler feedback loops between climate and UV radiation described in the report. For example, higher concentrations of carbon dioxide have led to more acidic oceans, which reduces the thickness of calcified shells, rendering shellfish more vulnerable to UV radiation. Even humans, he said, are likely to wear lighter clothes in a warmer atmosphere, making themselves more susceptible to damaging UV rays.The report found that climate change may also be affecting the ozone layer and how quickly the ozone layer is recovering."Greenhouse gas emissions trap more heat in the lower atmosphere which leads to a cooling of the upper atmosphere. Those colder temperatures in the upper atmosphere are slowing the recovery of the ozone layer," Rose said.As one of three scientific panels to support the Montreal Protocol, the Environmental Effects Assessment Panel focused in particular on the effects of UV radiation, climate change, and ozone depletion. Thirty-nine researchers contributed to the article, which is titled "Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future." Rose, an aquatic ecologist, serves on the aquatic ecosystems working group, which is one of seven working groups that are part of the panel."This international collaboration focusing on a pressing problem of global significance exemplifies the research vision of The New Polytechnic at Rensselaer," said Curt Breneman, dean of the Rensselaer School of Science."

Ozone Holes

June 12, 2019

https://www.sciencedaily.com/releases/2019/06/190612141340.htm

Old ice and snow yields tracer of preindustrial ozone

Using rare oxygen molecules trapped in air bubbles in old ice and snow, U.S. and French scientists have answered a long-standing question: How much have "bad" ozone levels increased since the start of the Industrial Revolution?

"We've been able to track how much ozone there was in the ancient atmosphere," said Rice University geochemist Laurence Yeung, the lead author of a study published online today in Researchers used the new data in combination with state-of-the-art atmospheric chemistry models to establish that ozone levels in the lower atmosphere, or troposphere, have increased by an upper limit of 40% since 1850."These results show that today's best models simulate ancient tropospheric ozone levels well," said Yeung. "That bolsters our confidence in their ability to predict how tropospheric ozone levels will change in the future."The Rice-led research team includes investigators from the University of Rochester in New York, the French National Center for Scientific Research's (CNRS) Institute of Environmental Geosciences at Université Grenoble Alpes (UGA), CNRS's Grenoble Images Speech Signal and Control Laboratory at UGA and the French Climate and Environmental Sciences Laboratory of both CNRS and the French Alternative Energies and Atomic Energy Commission (CEA) at the Université Versailles-St Quentin."These measurements constrain the amount of warming caused by anthropogenic ozone," Yeung said. For example, he said the most recent report from the Intergovernmental Panel on Climate Change (IPCC) estimated that ozone in Earth's lower atmosphere today is contributing 0.4 watts per square meter of radiative forcing to the planet's climate, but the margin of error for that prediction was 50%, or 0.2 watts per square meter."That's a really big error bar," Yeung said. "Having better preindustrial ozone estimates can significantly reduce those uncertainties."It's like guessing how heavy your suitcase is when there's a fee for bags over 50 pounds," he said. "With the old error bars, you'd be saying, 'I think my bag is between 20 and 60 pounds.' That's not good enough if you can't afford to pay the penalty."Ozone is a molecule that contains three oxygen atoms. Produced in chemical reactions involving sunlight, it is highly reactive, in part because of its tendency to give up one of its atoms to form a more stable oxygen molecule. The majority of Earth's ozone is in the stratosphere, which is more than five miles above the planet's surface. Stratospheric ozone is sometimes called "good" ozone because it blocks most of the sun's ultraviolet radiation, and is thus essential for life on Earth.The rest of Earth's ozone lies in the troposphere, closer to the surface. Here, ozone's reactivity can be harmful to plants, animals and people. That's why tropospheric ozone is sometimes called "bad" ozone. For example, ozone is a primary component of urban smog, which forms near ground level in sunlit-driven reactions between oxygen and pollutants from motor vehicle exhaust. The Environmental Protection Agency considers exposure to ozone levels greater than 70 parts per billion for eight hours or longer to be unhealthy."The thing about ozone is that scientists have only been studying it in detail for a few decades," said Yeung, an assistant professor of Earth, environmental and planetary sciences. "We didn't know why ozone was so abundant in air pollution until the 1970s. That's when we started to recognize how air pollution was changing atmospheric chemistry. Cars were driving up ground-level ozone."While the earliest measurements of tropospheric ozone date to the late 19th century, Yeung said those data conflict with the best estimates from today's state-of-the-art atmospheric chemistry models."Most of those older data are from starch-paper tests where the paper changes colors after reacting with ozone," he said. "The tests are not the most reliable -- the color change depends on relative humidity, for example -- but they suggest, nevertheless, that ground-level ozone could have increased up to 300% over the past century. In contrast, today's best computer models suggest a more moderate increase of 25-50%. That's a huge difference."There's just no other data out there, so it's hard to know which is right, or if both are right and those particular measurements are not a good benchmark for the whole troposphere," Yeung said. "The community has struggled with this question for a long time. We wanted to find new data that could make headway on this unsolved problem."Finding new data, however, is not straightforward. "Ozone is too reactive, by itself, to be preserved in ice or snow," he said. "So, we look for ozone's wake, the traces it leaves behind in oxygen molecules."When the sun is shining, ozone and oxygen molecules are constantly being made and broken in the atmosphere by the same chemistry," Yeung said. "Our work over the past several years has found a naturally occurring 'tag' for that chemistry: the number of rare isotopes that are clumped together."Yeung's lab specializes in both measuring and explaining the occurrence of these clumped isotopes in the atmosphere. They are molecules that have the usual number of atoms -- two for molecular oxygen -- but they have rare isotopes of those atoms substituted in place of the common ones. For example, more than 99.5% of all oxygen atoms in nature have eight protons and eight neutrons, for a total atomic mass number of 16. Only two of every 1,000 oxygen atoms are the heavier isotope oxygen-18, which contains two additional neutrons. A pair of these oxygen-18 atoms is called an isotope clump.The vast majority of oxygen molecules in any air sample will contain two oxygen-16s. A few rare exceptions will contain one of the rare oxygen-18 atoms, and rarer still will be the pairs of oxygen-18s.Yeung's lab is one of the few in the world that can measure exactly how many of these oxygen-18 pairs are in a given sample of air. He said these isotope clumps in molecular oxygen vary in abundance depending on where ozone and oxygen chemistry occurs. Because the lower stratosphere is very cold, the odds that an oxygen-18 pair will form from ozone/oxygen chemistry increase slightly and predictably compared to the same reaction in the troposphere. In the troposphere, where it is warmer, ozone/oxygen chemistry yields slightly fewer oxygen-18 pairs.With the onset of industrialization and the burning of fossil fuels around 1850, humans began adding more ozone to the lower atmosphere. Yeung and colleagues reasoned that this increase in the proportion of tropospheric ozone should have left a recognizable trace -- a decrease in the number of oxygen-18 pairs in the troposphere.Using ice cores and firn (compressed snow that has not yet formed ice) from Antarctica and Greenland, the researchers constructed a record of oxygen-18 pairs in molecular oxygen from preindustrial times to the present. The evidence confirmed both the increase in tropospheric ozone and the magnitude of the increase that had been predicted by recent atmospheric models."We constrain the increase to less than 40%, and the most comprehensive chemical model predicts right around 30%," Yeung said."One of the most exciting aspects was how well the ice-core record matched model predictions," he said. "This was a case where we made a measurement, and independently, a model produced something that was in very close agreement with the experimental evidence. I think it shows how far atmospheric and climate scientists have come in being able to accurately predict how humans are changing Earth's atmosphere -- particularly its chemistry."

Ozone Holes

June 11, 2019

https://www.sciencedaily.com/releases/2019/06/190611133947.htm

Electric vehicles would be a breath of fresh air for Houston

Cornell University researchers are expressing hope for the future of Houston's breathable air, despite the city's poor rankings in the American Lung Association's 2019 "State of the Air" report.

The report, released in April, ranked Houston ninth nationally for worst ozone pollution and 17th for particle pollution.Researchers say replacing at least 35 percent of Houston's gasoline cars and diesel trucks with electric vehicles by 2040 will reduce pollution and improve air quality by 50 percent."The built environment plays a significant role in affecting our daily life and health," said H. Oliver Gao, professor of civil and environmental engineering and senior author of "Potential Impacts of Electric Vehicles on Air Quality and Health Endpoints in the Greater Houston Area in 2040," published in "While transportation provides us with mobility, it impacts our environment and our public health," said Gao, who directs Cornell's Center for Transportation, Environment and Community Health and is a fellow at Cornell's Atkinson Center for a Sustainable Future. "We are enjoying this mobility at a very high cost."Shuai Pan, postdoctoral associate in civil and environmental engineering, along with Gao and a team of chemists and engineers, modeled four scenarios using various levels of electric car adoption to see how Houston's air quality and public health likely would respond two decades from now."The population in 2040 Houston will see a huge increase, but we can apply new technology to reduce emissions, improve air quality and think about health," said Pan, who earned his Ph.D. in atmospheric science from the University of Houston in 2017.In their exhaust, gasoline and diesel vehicles emit nitrogen oxides -- volatile organic compounds that react in the presence of sunlight to form ozone and increase detrimental fine particulates, elements known to harm human health.If left unchecked, current ozone and particulate-matter levels would result in 122 more premature deaths annually throughout greater Houston by 2040. With moderate or aggressive electrification for cars and trucks, the numbers reflect air-quality improvement, with prevented premature deaths at 114 and 188, respectively.In the case of complete turnover to electric vehicles, the number of prevented premature deaths per year around Houston shoots to 246."Mayors or policymakers -- who care about the environment, the economy and public health -- must advocate for electrification," Gao said. "The knowledge is there, but we need mayors and city planners to be creative and innovative to design policies that would help the electrification of the transportation sector."

Ozone Holes

May 28, 2019

https://www.sciencedaily.com/releases/2019/05/190528140115.htm

A warming Arctic produces weather extremes in our latitudes

Atmospheric researchers at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now developed a climate model that can accurately depict the frequently observed winding course of the jet stream, a major air current over the Northern Hemisphere. The breakthrough came when the scientists combined their global climate model with a new machine learning algorithm on ozone chemistry. Using their new combo-model, they can now show that the jet stream's wavelike course in winter and subsequent extreme weather conditions cold air outbreaks in Central Europe and North America are the direct result of climate change. Their findings were released in the Nature online portal

For years, climate researchers around the globe have been investigating the question as to whether the jet stream's winding course over the Northern Hemisphere -- observed with increasing frequency in recent years -- is a product of climate change, or a random phenomenon that can be traced back to natural variations in the climate system. The term "jet stream" refers to a powerful band of westerly winds over the middle latitudes, which push major weather systems from west to east. These winds whip around the planet at an altitude of roughly 10 kilometres, are driven by temperature differences between the tropics and the Arctic, and in the past, often reached top speeds of up to 500 kilometres per hour.But these days, as observations confirm, the winds are increasingly faltering. They less often blow along a straight course parallel to the Equator; instead, they sweep across the Northern Hemisphere in massive waves. In turn, during the winter these waves produce unusual intrusions of cold air from the Arctic into the middle latitudes -- like the extreme cold that struck the Midwest of the USA in late January 2019. In the summer, a weakened jet stream leads to prolonged heat waves and dry conditions, like those experienced in Europe in e.g. 2003, 2006, 2015 and 2018.These fundamental connections have been known for some time. Nevertheless, researchers hadn't succeeded in realistically portraying the jet stream's wavering course in climate models or demonstrating a connection between the faltering winds and global climate change. Atmospheric researchers at the AWI in Potsdam have now passed that hurdle by supplementing their global climate model with an innovative component for ozone chemistry. "We've developed a machine learning algorithm that allows us to represent the ozone layer as an interactive element in the model, and in so doing, to reflect the interactions from the stratosphere and ozone layer," says first author and AWI atmospheric researcher Erik Romanowsky. "With the new model system we can now realistically reproduce the observed changes in the jet stream."According to the team's findings, sea-ice retreat and the accompanying increased activity of atmospheric waves are creating a significant, ozone-amplified warming of the polar stratosphere. Since the low polar temperatures form the jet stream's motor, the rising temperatures in the stratosphere are causing it to falter. In turn, this weakening of the jet stream is now spreading downward from the stratosphere, producing weather extremes.In addition, with the new model the researchers can also more closely analyse the causes of the meandering jet stream. "Our study shows that the changes in the jet stream are at least partly due to the loss of Arctic sea ice. If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase," says Prof Markus Rex, Head of Atmospheric Research at the AWI. "In addition, our findings confirm that the more frequently occurring cold phases in winter in the USA, Europe and Asia are by no means a contradiction to global warming; rather, they are a part of anthropogenic climate change."The team's efforts also represent a significant technological advance: "After the successful use of machine learning in this study, we are now for the first time employing artificial intelligence in climate modelling, helping us arrive at more realistic climate model systems. This holds tremendous potential for future climate models, which we believe will deliver more reliable climate projections and therefore a more robust basis for political decision-making," says Markus Rex.During the Arctic expedition MOSAiC, which will begin in September and during which the German research icebreaker Polarstern will drift through the Central Arctic along with the sea ice for an entire year, the researchers plan to gather the latest ice and atmospheric data. This will help them apply the new climate model to the future, so as to simulate the future development of the Arctic climate and sea ice. As Markus Rex explains, "Our goal is to understand in detail how the Arctic sea-ice retreat will progress -- because only then will we be able to gauge how and on what scale the changes in the Arctic will lead to weather extremes in the middle latitudes."

Ozone Holes

May 22, 2019

https://www.sciencedaily.com/releases/2019/05/190522141837.htm

Reductions in PM over decade has improved health; ozone pollution remains little changed

Fewer deaths and serious illnesses have occurred in the U.S. over the past decade as a result of cleaner air, according to a new report focusing on the two most potent air pollutants: fine particle (PM2.5) and ground-level ozone (O

The report, presented at ATS 2019 and published online in the In "Trends in Excess Morbidity and Mortality Associated with Air Pollution above ATS-Recommended Standards, 2008 to 2017," researchers report that mortality impacts of air pollution above these ATS-recommended levels fell by nearly half in the last decade as most U.S. counties have seen significant improvements in PM2.5, while health impacts from OThe report's findings are based on the ATS's recommendations for PM2.5 (11 micrograms per cubic meter for annual concentrations and 25 micrograms per cubic meter for short-term concentrations) and OUsing air quality data from more than 500 counties with PM2.5 data and more than 700 counties with OBased on the levels of the two pollutants, the researchers also quantified serious illnesses (morbidities) and missed school and work days (impacted days). In 2017, the most recent year that pollution data is available, PM2.5 pollution above recommended levels was estimated to cause an additional 5,600 morbidities and 2,804,000 impacted days. That same year, OThe latest report found that in addition to the lack of consistent improvement in the health impacts associated with OThe report also highlighted other challenges to reducing deaths and illness due to air pollution."The proposed roll back of several Clean Air Act regulations and the proposed roll back of the greenhouse gas standard for automobiles will make it hard for communities to maintain their air quality, and even harder for cities with poor air quality to clean up," said report co-author Gary Ewart, MHS, chief of ATS advocacy and government relations.The authors also noted that the effects of wildfires contributing to pollution levels above EPA regulatory levels were excluded from the study, but their increasing frequency and severity may limit the improvements in health that cities and counties can achieve by reducing other air pollution sources.Ground-level ozone occurs when sunlight causes a chemical reaction among so-called precursor pollutants, primarily nitric oxides and volatile organic compounds, and forms ozone molecules.Recently, the U.S. Environment Protection Agency designated many locations in the country as "being in nonattainment" of the national ambient air quality standard for ozone. States that do not show improvement in the next three years will be required to develop a plan for achieving attainment."The large number of adverse health impacts attributable to ozone should motivate cities and states to start now to reduce their local emissions of precursors pollutants," said lead author Kevin Cromar, PhD, director of the Air Quality Program at the Marron Institute and associate professor of population health and environmental medicine at the NYU School of Medicine. "Coordinated actions at the regional level, as well as strong actions at the federal level, will also be needed in order to make consistent gains in reducing ozone in many parts of the country."The latest report is also available online at Both the report and the online tool identify the top ten cities for adverse health impacts from PM2.5 and ORank City Annual Excess Mortality(PM2.5 and O1 Los Angeles-Long Beach-Glendale, CA 1,322 12 Riverside-San Bernardino-Ontario, CA 940 23 Bakersfield, CA 293 64 Pittsburgh, PA 232 35 Fresno, CA 225 116 New York-Jersey City-White Plains, NY-NJ 188 57 Phoenix-Mesa-Scottsdale, AZ 152 198 Visalia-Porterville, CA 131 239* Cleveland-Elyria, OH 116 810* Chicago-Naperville-Arlington Heights, IL 122 4*Rankings based on a weighting of the combined health impacts of air pollution, including mortality, lung cancer, morbidity and impacted days.More information on the annual health impacts from 2010-17 for every city and county with an air pollution monitor is also available in the supplementary materials that accompany the published report.

Ozone Holes

May 22, 2019

https://www.sciencedaily.com/releases/2019/05/190522141808.htm

Scientists discover the source of new CFC emissions

Since 2013, annual emissions of a banned chlorofluorocarbon (CFC) have increased by around 7,000 tonnes from eastern China, according to new research published in

Last year, it was reported that emissions of one of the most important ozone depleting substances, CFC-11, had increased. This chemical was used primarily as a foaming agent for building insulation, refrigerators and other consumer products. The surprise finding indicated that someone, somewhere was likely producing and emitting thousands of tonnes of CFC-11, despite a global phase-out since 2010 under the Montreal Protocol.Dr Matt Rigby, a lead author of the study and Reader in Atmospheric Chemistry in the School of Chemistry at the University of Bristol, explained: "Through global monitoring networks such as the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Oceanic and Atmospheric Administration Global Monitoring Division (NOAA GMD), scientists have been making measurements of chlorofluorocarbons (CFCs) in the atmosphere for over 40 years."In recent decades, we've primarily seen declining CFC emissions reflected in these measurements, because of the Montreal Protocol. Therefore, it was unexpected when it was reported last year that, starting around 2013, global emissions of one of the most important CFCs suddenly began to grow."This finding was concerning because CFCs are the main culprits in depletion of the stratospheric ozone layer, which protects us from the sun's ultra-violet radiation. Any increase in emissions of CFCs will delay the time it takes for the ozone layer, and the Antarctic ozone "hole", to recover.But where were these new emissions coming from? Until now, researchers only had an indication that at least part of the source was located somewhere in eastern Asia."Initially our monitoring stations were set up in remote locations, far from potential sources," said Ron Prinn, co-author of the new study, leader of the AGAGE network and professor at the Massachusetts Institute of Technology (MIT). "This was because we were interested in collecting air samples that were representative of the background atmosphere, so that we could monitor global changes in concentration and determine their atmospheric lifetimes."To better pinpoint emissions sources, more recent measurement stations have been located closer to industrialised regions. In this case, the clue to the location of the new CFC-11 emissions came from an AGAGE station in South Korea and an AGAGE-affiliated station run by the National Institute of Environmental Studies (NIES) in Japan.Professor Sunyoung Park from Kyungpook National University in South Korea, a lead author on the new study, who runs the South Korean Gosan measurement station, explained: "Our measurements show 'spikes' in pollution, when air arrives from industrialised areas. For CFC-11, we noticed that the magnitude of these spikes increased after 2012, indicating that emissions must have grown from somewhere in the region."Similar signals had also been noticed at the NIES station on the Japanese island of Hateruma, close to Taiwan.To establish which countries were responsible for the growing pollution levels at these stations, an international team of modelling groups at University of Bristol, the UK Met Office, the Swiss Federal Laboratories for Materials Science and Technology (Empa) and MIT ran sophisticated computer simulations that determined the origin of the polluted air samples."From the Korean and Japanese data, we used our models to show that emissions of CFC-11 from eastern China had increased by around 7,000 tonnes per year after 2012, particularly in or around the provinces of Shandong and Hebei.", said Dr Luke Western, post-doctoral researcher at the University of Bristol."We didn't find evidence of increasing emissions from Japan, the Korean peninsula, or any other country to which our networks are sensitive."To investigate the possibility that the new emissions from China could be the result of a release to the atmosphere of CFC-11 that was produced before the ban, the team considered a range of possibilities.Dr Rigby said: "CFC-11 was used primarily in foam blowing, so we looked at estimates of the amount of CFC-11 that could be locked up in insulating foams in buildings or refrigerators that were made before 2010, but the quantities were far too small to explain the recent rise."The most likely explanation is that new production has taken place, at least prior to the end of 2017, which is the period covered in our work."Whilst the new study has identified a substantial fraction of the global emissions rise, it is possible that smaller increases have also taken place in other countries, or even in other parts of China.Professor Park explained: "Our measurements are sensitive only to the eastern part of China, western Japan and the Korean peninsula and the remainder of the AGAGE network sees parts of North America, Europe and southern Australia. There are large swathes of the world for which we have very little detailed information on the emissions of ozone depleting substances."Nevertheless, this study "represents an important and particularly policy-relevant milestone in atmospheric scientists' ability to tell which regions are emitting ozone-depleting substances, greenhouse gases, or other chemicals, and in what quantities," said Professor Ray Weiss, a geochemist at Scripps Institution of Oceanography at the University of California San Diego and study co-author.Dr Rigby said: "It is now vital that we find out which industries are responsible for the new emissions. If the emissions are due to the manufacture and use of products such as foams, it is possible that we have only seen part of the total amount of CFC-11 that was produced. The remainder could be locked up in buildings and chillers and will ultimately be released to the atmosphere over the coming decades."Previous reports by the Environmental Investigation Agency and the New York Times have suggested that Chinese foam manufacturers were using CFC-11 after the global ban. Furthermore, Chinese authorities have recently identified and closed down some illegal production facilities.Whilst this new study cannot determine which industry or industries are responsible, it provides a clear indication of large increases in emissions of CFC-11 from China in recent years. These increases, likely from new production, account for a substantial fraction of the concurrent global emission rise.  

Ozone Holes

April 25, 2019

https://www.sciencedaily.com/releases/2019/04/190425143637.htm

Human encroachment alters air quality over Amazon rainforest

Plumes of air pollution generated from a rapidly expanding city within the Amazon rainforest are wafting hundreds of miles and degrading air quality in the pristine rainforest, according to a team of scientists.

Urban emissions from Manaus, a city of more than two million in Brazil, lead to elevated levels of ozone, a greenhouse gas and a harmful pollutant to human health, and the formation of aerosols in the atmosphere above the rainforest, the team reported in "Through this study of the Amazon rainforest, we can get a better idea of how human activities are influencing the conditions in what has been considered a pristine environment," said Dandan Wei, who led the research as a doctoral student in the College of Earth and Mineral Sciences at Penn State. Wei is now a postdoctoral researcher at the University of Michigan.Scientists observed ozone levels 30 to 50 percent higher than baseline conditions at a location 60 miles downwind of the city. The elevated levels were not present at a site upwind.The researchers tracked how air-polluted plumes move from the city into the rainforest and how they mix with the plant-emitted gases in the atmosphere above the rainforest under the influence of the tropical sunlight.Vehicle emissions and other human activities in the city release nitrogen oxides into the atmosphere. The emissions mix with volatile organic compounds (VOCs) naturally released by vegetation and, in the presence of sunlight, produce chemicals that can influence regional air quality, weather and climate."When you have these gases emitted by the cities in the presence of other molecules produced by the trees, you have this chemistry that is baking, cooking in the warm and moist tropical atmosphere and it's producing all sorts of chemicals," said Jose D. Fuentes, professor of atmospheric science at Penn State, and Wei's adviser.Using computer models, the researchers found levels of nitrogen oxide like those emitted from Manaus can cause up to a 260-percent increase in ozone and a 150-percent increase in hydroxyl radicals, a potent oxidant."These findings suggest that emissions from Manaus can substantially modify the natural chemistry of the atmosphere over the Amazon rainforest," Wei said.Scientists also found as air temperature increases due to climate change, the urban emissions result in more ozone production. In the rainforest, where air temperature is rising by nearly half a degree Fahrenheit per decade, additional greenhouse gases in the atmosphere could expedite the warming, according to the researchers."Ozone is an important greenhouse gas," Fuentes said. "If we are venting more of this molecule into the lower atmosphere, we are producing something that can create a positive feedback loop in the climate system. We are contributing to having a greater degree of warming in the lower atmosphere."The molecules are harmful to humans if inhaled and can cause environmental damage to the vegetation in the rainforest as well, the scientists said."This research illustrates the extent that humans can modify these pristine environments," Fuentes said. "The rainforests are the lungs of our planet and those lungs impact us even here in State College, Pennsylvania, because air masses circulate around the globe."Tobias Gerken, assistant research professor, Penn State; Amy Trowbridge, assistant professor, and Paul Stoy, associate professor, Montana State University; and Marcelo Chamecki, associate professor, University of California, Los Angeles, collaborated on the study.The U.S. Department of Energy funded this research through the GoAmazon project.

Ozone Holes

April 24, 2019

https://www.sciencedaily.com/releases/2019/04/190424153525.htm

Particulate matter takes away 125,000 years of healthy life from Europe's child population

A study led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by "la Caixa," has estimated the disease burden for various environmental exposure factors among the child population of Europe, and once again highlights the risk posed by air pollution. The study calculates that every year exposure to particulate matter of less than 10 micrograms (PM

This analysis, published in the Population and health data were compiled from several European databases and the analysis of the environmental burden of disease was conducted in line with the comparative risk assessment approach proposed by the World Health Organisation (WHO) and the Global Burden of Disease (GBD) project. The researchers calculated disability-adjusted life years (DALYs), a measure of overall burden of disease expressed as the number of years of healthy life lost to illness, disability or premature death.The conclusions show that the environmental exposure factors included in this study take away 211,000 years of healthy life from the European population under 18 years old, accounting for 2.6% of the total. Air pollution (PM"The environmental factors included in the study were chosen according to various criteria: they are the exposures for which the most data exist at national level and also those for which there is evidence of a causal relationship with effects on health, among others," states David Rojas, the lead author of the study.The researcher emphasises that "out of all the risks studied, particulate matter are those that cause the greatest burden of disease, as they are associated with respiratory, cardiovascular and neurological illnesses, among others, as well as with higher infant mortality." "In fact, their real impact may be higher than that indicated by our estimates, as we have only taken into account their effects on infant mortality and asthma in the case of PMOut of the 28 countries included in the study, 22 - the exceptions were Luxembourg, Ireland, Sweden, Estonia, Finland and Denmark -- reported PMMark Nieuwenhuijsen, coordinator of the study and of the Urban Planning, Environment and Health Initiative at ISGlobal, points out that "this study shows the pressing need to implement effective policies to reduce children's exposure to environmental risk factors throughout Europe, paying special attention to air pollution and passive smoking." The researcher also points out that "common European databases need to be created to compile and harmonise exposure data for environmental risk factors, especially in childhood, as well as conducting epidemiological studies of multiple environmental risk factors."

Ozone Holes

April 17, 2019

https://www.sciencedaily.com/releases/2019/04/190417194913.htm

How bacteria build an enzyme that destroys climate-changing laughing gas

New research from the University of East Anglia reveals how soil bacteria build the only known enzyme for the destruction of the potent global warming and ozone-depleting gas nitrous oxide.

Alongside carbon dioxide (COIt is hoped that the findings, published today in the journal NIt also destroys the ozone layer with similar potency to the now banned chlorofluorocarbons (CFCs).Atmospheric levels of NProf Nick Le Brun from UEA's School of Chemistry, said: "It is well known that some bacteria can 'breathe' N"This ability is entirely dependent on an enzyme called 'nitrous oxide reductase', which is the only enzyme known to destroy N"We wanted to find out more about how soil bacteria use this enzyme to destroy nitrous oxide."The part of the enzyme where NThe UEA team discovered a protein called NosL, which is required for the assembly of the copper-sulfide cluster active site and makes the enzyme active.They found that bacteria lacking NosL still produced the enzyme but it contained less of the copper-sulfide active site. Furthermore, when the same bacteria were grown with copper in short supply, the active site was completely absent from the enzyme.The team also showed that NosL is a copper-binding protein, indicating that it functions directly in supplying copper for the assembly of the copper-sulfide cluster active site.Prof Le Brun said: "The discovery of the function of NosL is the first step towards understanding how the unique active site of nitrous oxide reductase is assembled. This is key information because when assembly goes wrong, inactive enzyme leads to release of NThe UEA team was led by Prof Nick Le Brun and Dr Andy Gates from UEA's School of Biological Sciences, and included the University's Vice Chancellor Prof David Richardson -- also from the School of Biological Sciences. They are part of international EU network focussed on understanding different aspects of NDr Gates said: "Society is generally well aware of the need to address carbon dioxide emissions, but nitrous oxide is now emerging as a pressing global concern and requires researchers with different skill sets to work together to prevent further damaging effects of climate change."With increasing understanding of the enzymes that make and destroy N'NosL is a dedicated copper chaperone for assembly of the Cuz center of nitrous oxide reductase' is published in

Ozone Holes

April 12, 2019

https://www.sciencedaily.com/releases/2019/04/190412122912.htm

Electric vehicle adoption improves air quality and climate outlook

If you have ever wondered how much electric vehicle (EV) adoption actually matters for the environment, a new study provides evidence that making this switch would improve overall air quality and lower carbon emissions.

The Northwestern University study quantified the differences in air pollution generated from battery-powered electric vehicles versus internal combustion engines. The researchers found that even when their electricity is generated from combustion sources, electric vehicles have a net positive impact on air quality and climate change."In contrast to many of the scary climate change impact stories we read in the news, this work is about solutions," said Northwestern's Daniel Horton, senior author of the study. "We know that climate change is happening, so what can we do about it? One technologically available solution is to electrify our transportation system. We find that EV adoptions reduces net carbon emissions and has the added benefit of reducing air pollutants, thereby improving public health."The research published Friday, April 5 in the journal To quantify the differences between the two types of vehicles, the researchers used an emissions remapping algorithm and air quality model simulations. They used these methods to closely examine two pollutants related to automobiles and power emissions: ozone and particulate matter. Both are main components of smog and can trigger a variety of health problems, such as asthma, emphysema and chronic bronchitis.To fully account for the complexity of changes to air pollution chemistry, the researchers took multiple variables into consideration:Ozone levels decreased across the board in simulations of warmer weather months. In the wintertime, however, ozone levels increase slightly but are already much lower compared to summer due to a chemical reaction that occurs differently during times of lesser winter sunlight."Across scenarios, we found the more cars that transitioned to electric power, the better for summertime ozone levels," Schnell said. "No matter how the power is generated, the more combustion cars you take off the road, the better the ozone quality."Particulate matter, which is also called "haze," decreased in the wintertime but showed greater variation based on location and how the power was generated. Locations with more coal-fired power in their energy mix, for example, experienced an increase in haze during the summer. Locations with clean energy sources, however, saw drastic reductions in human-caused haze."We found that in the Midwest, the increased power demands of EV charging in our current energy mix could cause slight increases in summer particulate matter due to the reliance on coal-fired power generation," Schnell said. "However, if we transition more of the Midwest's power generation to renewables, particulate matter pollution is substantially reduced. In the Pacific Northwester or Northeast, where there is already more clean power available, EV adoption -- even with the current energy mix -- will decrease particulate matter pollution."The research was supported by the Ubben Program for Carbon and Climate Science and the National Science Foundation (grant number CBET-1848683).

Ozone Holes

April 10, 2019

https://www.sciencedaily.com/releases/2019/04/190410083101.htm

How severe drought influences ozone pollution

From 2011 to 2015, California experienced its worst drought on record, with a parching combination of high temperatures and low precipitation. Drought conditions can have complicated effects on ozone air quality, so to better understand the process, researchers have analyzed data from two ozone-polluted cities before, during and after the California drought. They report their results in ACS' journal

Although ozone in the stratosphere protects the earth from ultraviolet radiation, at ground level the molecule is a harmful air pollutant to humans, animals and plants. Ground-level ozone forms when nitrogen oxide compounds, primarily from motor vehicle emissions, react with volatile organic compounds (VOCs) from natural and anthropogenic sources. Isoprene, a VOC emitted by plants, is a significant contributor to ozone production during summer months in many locations around the world. However, plants also decrease air ozone levels by taking the gas up through pores in their leaves. Because drought conditions affect both of these plant-related processes, Angelique Demetillo, Sally Pusede and colleagues wanted to examine air concentrations of isoprene and ozone -- as well as leaf area index, nitrogen dioxide and meteorology -- before, during and after the California drought.For their study, the researchers analyzed publicly available data collected from the ground and satellites in Fresno, an ozone-polluted city close to an oak savanna, and Bakersfield, California. They found that isoprene concentrations did not change significantly during the early drought, but they dropped by more than 50 percent during the most severe drought conditions. The effects of drought on isoprene were also dependent on atmospheric temperature. The researchers found that drought altered ozone production such that the process became chemically more sensitive to the decrease in isoprene and other drought-affected VOCs. These factors led to an estimated overall decrease in ozone production of approximately 20 percent during the severe drought. However, this decrease was offset by a comparable reduction in ozone uptake by plants, leading to only a 6 percent reduction in ozone levels overall during the severe drought period. These results suggest that drought influences on ozone pollution are complex and depend on drought severity and duration, the researchers say.

Ozone Holes

April 10, 2019

https://www.sciencedaily.com/releases/2019/04/190410090331.htm

Green roofs could reduce indoor air pollution

Green roofs -- roofs that are planted with vegetation -- may improve the indoor air quality of commercial buildings by cutting the amount of ozone coming into the buildings from the outside, according to new research from Portland State University.

The findings add to the already known environmental benefits of green roofs, including reducing carbon dioxide, decreasing storm water runoff and cutting down on urban heat, according to PSU researchers.The researchers from PSU's departments of Mechanical and Materials Engineering, Biology and the university's Honors College, set up measuring devices on the roof of a big-box retail store in North Portland that was split between a green roof and a more conventional white membrane roof.They measured the air coming into the building from outdoor intake vents, and found that the air coming in from the green roof area had modestly lower ozone levels than the air coming in from the unplanted area. They found that the vegetation trapped and filtered the ozone in the outdoor air.The trapping effect is a process known as dry deposition, in which airborne particles collect or deposit themselves on solid surfaces. It's a natural process that is key to removing pollutants from the atmosphere.The study was conducted over a two-day period. The authors said the findings warrant a longer-term study -- one that could include measuring other pollutants as well as ozone.

Ozone Holes

April 9, 2019

https://www.sciencedaily.com/releases/2019/04/190409164002.htm

Kids living near major roads at higher risk of developmental delays

Young children who live close to a major roadway are twice as likely to score lower on tests of communications skills, compared to those who live farther away from a major roadway, according to an analysis by researchers at the National Institutes of Health and the University of California, Merced. Moreover, children born to women exposed during pregnancy to higher-than-normal levels of traffic-related pollutants -- ultra-fine airborne particles and ozone -- had a small but significantly higher likelihood of developmental delays during infancy and early childhood. The study appears in

"Our results suggest that it may be prudent to minimize exposure to air pollution during pregnancy, infancy, and early childhood -- all key periods for brain development," said Pauline Mendola, Ph.D., an investigator in the Division of Intramural Population Health Research at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the study's senior author.Previous studies have linked exposure to common air pollutants in pregnancy to low birthweight, preterm birth and stillbirth. A few studies have found a higher risk of autism and of lower cognitive functioning in children living near freeways, but results of studies about how prenatal and early childhood exposure to air pollution might affect development have been inconsistent.Given that a large proportion of the U.S. population lives close to major roadways, which are major sources of air pollution, the researchers sought to determine if living near heavily traveled roads was linked to lower scores on developmental screens -- questionnaires or checklists that indicate whether a child is developing normally or needs to be referred to a specialist for further testing.The researchers analyzed data from the Upstate KIDS Study. They matched the addresses of 5,825 study participants to a roadway data set, calculating the distance of each address to the nearest major roadway. For each participant, they matched home address, mother's work address during pregnancy, and address of the child's day care location to an Environmental Protection Agency data set for estimating air pollution levels. From 8 months to 36 months of age, the children were screened every 4 to 6 months with the Ages and Stages Questionnaire, a validated screening measure evaluating five domains of child development: fine motor skills, large motor skills, communication, personal social functioning and problem-solving ability.Compared to children living more than half a mile from a major roadway, children living from roughly 164 feet to .3 miles from a major roadway were twice as likely to have failed at least one screen of the communications domain.The researchers also estimated exposures to ozone and fine inhalable particles (PM2.5), two pollutants produced by car traffic. Fine inhalable particles are 30 times smaller than the width of a human hair, can pass through the lungs' defenses, and are absorbed directly into the bloodstream.Prenatal exposure to elevated PM2.5 led to a 1.6 to 2.7 percent higher risk of failing any developmental domain, while higher ozone exposure led to a .7 to 1.7 percent higher risk of failing a developmental domain. In contrast, higher postnatal exposure to ozone was linked to a 3.3 percent higher risk of failing most domains of the developmental screen at 8 months, a 17.7 percent higher risk of overall screening failure at 24 months, and a 7.6 percent higher risk of overall screening failure at 30 months.These results led the researchers to conclude that early childhood exposure to air pollutants may convey a higher risk for developmental delays, compared to similar exposures in the womb. The study is associational and so cannot prove cause and effect. The authors noted that larger studies are necessary to confirm these links."It is not clear why exposure to pollutants after birth is linked to a higher risk of developmental delay," said Sandie Ha, Ph.D., of the Department of Public Health at the University of California, Merced, and lead author of the study. "However, unlike exposure during pregnancy, exposure during childhood is more direct and does not go through a pregnant woman's defenses."

Ozone Holes

March 26, 2019

https://www.sciencedaily.com/releases/2019/03/190326160515.htm

Air quality agencies can breathe easier about current emissions regulations

As air quality improves, the invisible chemistry happening in the air around us is changing. Skies should clear up as emissions drop, but recent results suggested that declining nitrogen oxides can create an environment where airborne carbon-containing compounds more easily convert into small particles that harm human health.

Regulators can now breathe easier. A University of Washington-led study, published in March in the Results show that declining NOx due to tighter standards does ultimately lead to cleaner air -- it just might take longer.A key finding is how the concentration of NOx affects the formation of PM2.5, found in smog, by changing the chemistry of the hydrocarbon vapors that transform into the particles less than 2.5 microns across, or about 3 percent the width of a human hair."We found that there are two different regimes of PM2.5 formation," said first author Joel Thornton, a UW professor of atmospheric sciences. "One where adding NOx enhances PM2.5, and one where adding NOx suppresses PM2.5."The findings could help explain why air quality appears to have stagnated in recent years over some parts of North America, even as emissions of all types have been dropping. Regulators are concerned because air pollution is a leading human health hazard, especially among children, the elderly and those with respiratory or heart problems.Officials knew to expect slow progress on reducing ozone, another component of smog, because of a somewhat similar role that NOx plays in ozone formation. But the recent concern was that PM2.5 concentrations might be different, and would just continue to go up with decreasing NOx emissions."We're basically saying: 'Hold on, don't worry. Things might look like they're getting worse, in some places, but overall they should get better,'" Thornton said.The discovery of this complex relationship could also help atmospheric scientists predict how air will change as emissions drop further.Hydrocarbon vapors -- carbon-based compounds from either natural sources or fossil fuels -- do not readily convert to PM2.5. Only through a set of chemical reactions in the air that involve free radicals, which are produced by sunlight and modulated by NOx, are hydrocarbon vapors converted into particulates.The research combines observations from a 2013 field campaign that measured emissions plumes in the air above Southeastern U.S. cities as well as experiments conducted at the Pacific Northwest National Laboratory.The ease with which hydrocarbons convert to PM2.5 shifts with the availability of the different ingredients, and the reaction rates also change. Both must be considered to understand the effect on regional PM2.5, the new study shows. Even though the process of PM2.5 formation from hydrocarbons gets easier as NOx drops, the chemical reactions slow down. Together the two effects mean that, eventually, drops in nitrogen oxides will lead to drops in PM2.5."You could be in a regime where it gets worse, but if you push past it, it gets better," Thornton said. "In most urban areas in the U.S., the NOx levels are low enough that we are past this point already."Previous research from Thornton's group has shown why winter air pollution is more resistant to emissions regulations than summer smog: because different temperatures provide seasonal conditions that send the chemistry down distinct paths.

Ozone Holes

March 20, 2019

https://www.sciencedaily.com/releases/2019/03/190320145559.htm

Turn off a light, save a life

We all know that turning off lights and buying energy-efficient appliances affects our financial bottom line. Now, according to a new study by University of Wisconsin-Madison researchers, we know that saving energy also saves lives and even more money for consumers by alleviating the costs of adverse health effects attributed to air pollution.

Writing this week in the journal "By saving electricity, we can also save lives," says Abel, of the Center for Sustainability and the Global Environment in UW-Madison's Nelson Institute for Environmental Studies. "There is a range of health benefits. It's a bonus. We find there are extra health reasons to turn off a light."Abel and his colleagues, including senior author Tracey Holloway, also of the Nelson Institute, deployed a suite of three widely used models to calculate power plant emissions, air quality and human mortality over a span of three summer months, when energy use is high. Their findings show that a 12 percent increase in summertime energy efficiency would reduce exposure to air pollution, specifically ozone and fine particulate matter. In short, cleaner air would save 475 human lives each year in the United States, worth an estimated $4 billion.That savings translates to almost 5 cents per kilowatt hour of energy used. That is a huge incentive, the Wisconsin team notes, given that electricity costs about 10 cents per kilowatt hour on average."We're trying to clarify how changes in energy systems have benefits for public health," explains Holloway, who is also a UW-Madison professor of atmospheric and oceanic sciences. "For the most part, the energy community is not focused on the human health effects of air pollution."By showing the savings and how to accurately gauge the value of lives saved and associated reduced health care costs, the UW team hopes to provide policymakers and the energy industry with a road map for assessing the human health benefits of reducing energy use. Ideally, putting a price tag on positive health outcomes related to reduced energy adds a new impetus to the existing strategies used by government and the energy industry to help consumers save energy.Air pollution such as ozone and fine particles caused by emissions from power plants adversely affect human health. They are known to contribute to an increased incidence of asthma attacks and other respiratory diseases in susceptible populations.The project to quantify the human health benefits of saving energy, says Holloway, emerged from an undergraduate class project that found that only one state, Texas, had used energy efficiency to meet air pollution targets. Many counties across the United States fail to meet ozone and particulate standards, as required by the Environmental Protection Agency."This seems like a missed opportunity," says Holloway. "Energy efficiency is free, yet it is not being included in the basket of solutions."An implicit goal of the new research, say Abel and Holloway, is to help build bridges between distinct sets of researchers and policymakers. In practice, people who focus on air pollution and those who focus on energy work in different worlds, the Wisconsin researchers say. Finding common threads and providing tools to integrate those different worlds will save money, improve human health, and equip government and industry to meet stated air quality goals.

Ozone Holes

February 21, 2019

https://www.sciencedaily.com/releases/2019/02/190221110438.htm

Indoor exposure to air pollution studied

In an

The study found that the local outdoor levels of certain pollutants and ozone were the most important determinants of indoor levels of the same air pollutants."Ample burning of wood in small-scale room heaters and sauna stoves is likely to increase chronic personal exposures in the neighborhood to particulate matter that contains substantial amounts of soot and hazardous organic compounds like polycyclic organic hydrocarbons. This exposure does not take place only while staying outdoors but also indoors at home due to effective passage of the small particles through the building shield," the authors wrote. "Part of the emissions adding this type of hazardous exposure among residents, also including susceptible population groups, originates directly from the personal use of a wood-fired room heater or sauna stove. Insufficient natural ventilation in older houses further elevates the indoor levels of the hazardous particles."

Ozone Holes

January 18, 2019

https://www.sciencedaily.com/releases/2019/01/190118123011.htm

Air pollution increases ER visits for breathing problems

As levels of ozone and fine particulate pollution (PM2.5) rise, more patients end up in the ER with breathing problems, according to the largest U.S. study of air pollution and respiratory emergency room visits of patients of all ages. The study was published online in the American Thoracic Society's

In "Age-specific Associations of Ozone and PM2.5 with Respiratory Emergency Department Visits in the U.S.," Heather M. Strosnider, PhD, MPH, and colleagues report on the associations between ground-level ozone and fine particulate pollution and ER visits for asthma, chronic obstructive pulmonary disease (COPD) and respiratory infections."Previous studies of ER visits related to respiratory illness have shown that children are particularly susceptible to air pollution, but those studies were mostly confined to a single city," said Dr. Strosnider, lead health scientist at the Centers for Disease Control and Prevention (CDC) National Environmental Public Health Tracking Program (Tracking Program). The researchers leveraged the data available through the Tracking Program to look at the association between air pollution and respiratory ER visits across hundreds of U.S. counties.Ozone, the main ingredient of smog, and fine particulate pollution, microscopic particles that penetrate deep into the lung, are two important forms of air pollution in the U.S. The study looked at the levels of these two pollutants in 869 counties in the week prior to an ER visit for a breathing problem. The study included nearly 40 million ER visits for breathing problems from the counties, which represent 45 percent of the U.S. population.The researchers divided patients into three groups: children under the age of 19, adults under the age of 65 and adults over the age of 65. The study found:The authors wrote that their study findings support the Environmental Protection Agency's "determination of a likely causal relationship between PM2.5 and respiratory effects and a causal relationship between ozone and respiratory effects." However, they emphasized that their study also found important variations in those relationships based on the age of the patient, the pollutant, and the respiratory illness under consideration.Dr. Strosnider said that study findings should guide efforts to protect those most vulnerable to air pollution. "For example, we observed strong associations for ozone among adults under 65 and for fine particulate pollution among children," she said. "This information can be used by public health officials and governments to make important decisions about air pollution and respiratory health in our communities."Study limitations include the fact that county air pollution measurements do not measure personal exposure and counties in the Northwest and mid-Atlantic were under-represented in the study.

Ozone Holes

January 14, 2019

https://www.sciencedaily.com/releases/2019/01/190114161150.htm

Antarctica losing six times more ice mass annually now than 40 years ago

Antarctica experienced a sixfold increase in yearly ice mass loss between 1979 and 2017, according to a study published today in

"That's just the tip of the iceberg, so to speak," said lead author Eric Rignot, Donald Bren Professor and chair of Earth system science at UCI. "As the Antarctic ice sheet continues to melt away, we expect multi-meter sea level rise from Antarctica in the coming centuries."For this study, Rignot and his collaborators conducted what he called the longest-ever assessment of remaining Antarctic ice mass. Spanning four decades, the project was also geographically comprehensive; the research team examined 18 regions encompassing 176 basins, as well as surrounding islands.Techniques used to estimate ice sheet balance included a comparison of snowfall accumulation in interior basins with ice discharge by glaciers at their grounding lines, where ice begins to float in the ocean and detach from the bed. Data was derived from fairly high-resolution aerial photographs taken from a distance of about 350 meters via NASA's Operation IceBridge; satellite radar interferometry from multiple space agencies; and the ongoing Landsat satellite imagery series, begun in the early 1970s.The team was able to discern that between 1979 and 1990, Antarctica shed an average of 40 gigatons of ice mass annually. (A gigaton is 1 billion tons.) From 2009 to 2017, about 252 gigatons per year were lost.The pace of melting rose dramatically over the four-decade period. From 1979 to 2001, it was an average of 48 gigatons annually per decade. The rate jumped 280 percent to 134 gigatons for 2001 to 2017.Rignot said that one of the key findings of the project is the contribution East Antarctica has made to the total ice mass loss picture in recent decades."The Wilkes Land sector of East Antarctica has, overall, always been an important participant in the mass loss, even as far back as the 1980s, as our research has shown," he said. "This region is probably more sensitive to climate [change] than has traditionally been assumed, and that's important to know, because it holds even more ice than West Antarctica and the Antarctic Peninsula together."He added that the sectors losing the most ice mass are adjacent to warm ocean water."As climate warming and ozone depletion send more ocean heat toward those sectors, they will continue to contribute to sea level rise from Antarctica in decades to come," said Rignot, who's also a senior project scientist at JPL.

Ozone Holes

January 2, 2019

https://www.sciencedaily.com/releases/2019/01/190102140749.htm

China's war on particulate air pollution is causing more severe ozone pollution

In early 2013, the Chinese government declared a war on air pollution and began instituting stringent policies to regulate the emissions of fine particulate matter, a pollutant known as PM 2.5. Cities restricted the number of cars on the road, coal-fired power plants reduced emissions or were shuttered and replaced with natural gas. Over the course of five years, PM 2.5 concentrations in eastern China have fallen nearly 40 percent.

The number of air quality monitoring stations across the country has grown to over 1,000, collecting unprecedented amounts of environmental data. Sifting through that data, researchers from the John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Nanjing University of Information Science & Technology (NUIST), found something surprising: While PM 2.5 pollution is falling, harmful ground-level ozone pollution is on the rise, especially in large cities.As it turns out, when it comes to the war on air pollution, chemistry is a formidable foe.Ozone is the main ingredient in smog and has been studied since it began choking cities in the U.S. in the early 1950s. "Ozone is formed through a series of chemical reactions, starting with the oxidation of volatile organic compounds (VOCs). This reaction forms chemical radicals, which drives reactions among oxides of nitrogen (NOx) and VOCs to produce ozone in the presence of sunlight. Both NOx and VOCs are emitted from fossil fuel combustion, and VOCs can also be emitted from industrial sources.The researchers from SEAS and NUIST found that particulate matter acts like a sponge for the radicals needed to generate ozone pollution, sucking them up and preventing them from producing ozone."There was so much particulate matter in Chinese cities that it stunted the ozone production," said Daniel Jacob, the Vasco McCoy Family Professor of Atmospheric Chemistry and Environmental Engineering, and co-corresponding author of the study.But the rapid reduction of PM 2.5 dramatically altered the chemistry of the atmosphere, leaving more radicals available to produce ozone."We haven't observed this happening anywhere else because no other country has moved this quickly to reduce particulate matter emissions," said Jacob. "It took China four years to do what took 30 years in the U.S."Despite this rapid reduction, China still has a long way to go to meet its air quality goals."As PM 2.5 levels continue to fall, ozone is going to keep getting worse," said Ke Li, a postdoctoral fellow at SEAS and first author of the study."Results from this study suggest that extra efforts are needed to reduce NOx and VOC emissions in order to stem the tide of ozone pollution," said Professor Hong Liao at NUIST who is the co-corresponding author of this work.

Ozone Holes

December 21, 2018

https://www.sciencedaily.com/releases/2018/12/181221123706.htm

Pollutants from wildfires affect crop and vegetation growth hundreds of kilometers from impact zone

Pollutants from wild fires affect crop and vegetation growth hundreds of kilometres from impact zone, research shows

The startling extent to which violent wild fires, similar to those that ravaged large swathes of California recently, affect forests and crops way beyond the boundaries of the blaze has been revealed.A pioneering new study by Professor Nadine Unger of the University of Exeter and Professor Xu Yue of the Institute of Atmospheric Physics in Beijing, has revealed that pollutants released by the devastating wild fires can affect crop and vegetation growth hundreds of kilometres from the fire impact zone.The study examined how ozone and aerosols -- two by-product pollutants of wildfires -- influences healthy plant growth in areas that are seemingly unaffected by the destructive natural disasters.It found that there was a significant reduction in plant productivity in areas far away from the fire's borders. The study suggests that fire pollution could pose an increasing threat to regional, and even global, productivity in the warming future world.The study is published in Professor Unger, from the University of Exeter's Mathematics department said: "The impacts of these wildfires on public health has been widely recognized, but the impact they also have on our ecosystems is less known."What we have found is that the pollutants released by these fires impact plants in areas way beyond the boundaries of the disaster. Globally, over the past decade, fire ozone pollution reduced plant productivity substantially more than estimated drought losses."The impact of fire on the Earth's carbon budget has been well documented. Each year, global fires directly emit large amounts of carbon directly into the atmosphere. This immediate carbon loss is partially compensated by a boost in new ecosystem productivity, driven by changes to canopy composition and soil respiration.For the study, scientists used state-of-the-art computer models, together with a vast array of existing measurement datasets, to assess the separate and combined effects of fire pollutants from 2002-11.It found that the Gross Primary Productivity (GPP) -- essentially plant photosynthesis -- was significantly reduced when the amount of surface ozone increases.Crucially, this reduction in GPP was not confined to the areas immediately in and surrounding the fires. It found that areas downwind from the fires, hundreds of kilometres away, experienced significantly reduced plant productivity.Crops and vegetation in sub-Saharan Africa were identified as a particularly vulnerable hot spots to fire ozone pollution damage.The study suggests that the ecological impacts of this air pollution is far greater than previously thought -- potentially impacting crop production that is crucial to the survival of rural, remote communities.Professor Unger added: "To the extent that we are worried about fire particulate pollution affecting human respiratory health, we need to be concerned about fire ozone pollution damaging forest and agricultural productivity downwind. We are now using the UK Met Office Hadley Centre Earth System Model to predict how increasing fire activity, air pollution, and drought affect the ability of the land surface to grow food and to take up carbon dioxide in the future warmer world."

Ozone Holes

December 20, 2018

https://www.sciencedaily.com/releases/2018/12/181220111756.htm

Chloroform emissions could delay ozone recovery by up to 8 years

Earlier this year, the United Nations announced some much-needed, positive news about the environment: The ozone layer, which shields the Earth from the sun's harmful ultraviolet radiation, and which was severely depleted by decades of human-derived, ozone-destroying chemicals, is on the road to recovery.

The dramatic turnaround is a direct result of regulations set by the 1987 Montreal Protocol, a global treaty under which nearly every country in the world, including the United States, successfully acted to ban the production of chlorofluorocarbons (CFCs), the main agents of ozone depletion. As a result of this sustained international effort, the United Nations projects that the ozone layer is likely to completely heal by around the middle of the century.But a new MIT study, published in They were able to trace the source of these emissions to East Asia, where it appears that production of products from chloroform is on the rise. If chloroform emissions continue to increase, the researchers predict that the recovery of the ozone layer could be delayed by four to eight years."[Ozone recovery] is not as fast as people were hoping, and we show that chloroform is going to slow it down further," says co-author Ronald Prinn, the TEPCO Professor of Atmospheric Science at MIT. "We're getting these little side stories now that say, just a minute, species are rising that shouldn't be rising. And certainly a conclusion here is that this needs to be looked at."Xuekun Fang, a senior postdoc in Prinn's group, is the lead author of the paper, which includes researchers from South Korea, Japan, England, Australia, and California.Chloroform is among a class of compounds called "very short-lived substances" (VSLS), for their relatively brief stay in the atmosphere (about five months for chloroform). If the chemical were to linger, it would be more likely to get lofted into the stratosphere, where it would, like CFCs, decompose into ozone-destroying chlorine. But because it is generally assumed that chloroform and other VSLSs are unlikely to do any real damage to ozone, the Montreal Protocol does not stipulate regulating the compounds."But now that we're at the stage where emissions of the more long-lived compounds are going down, the further recovery of the ozone layer can be slowed down by relatively small sources, such as very short-lived species -- and there are a lot of them," Prinn says.Prinn, Fang, and their colleagues monitor such compounds, along with other trace gases, with the Advanced Global Atmospheric Gases Experiment (AGAGE) -- a network of coastal and mountain stations around the world that has been continuously measuring the composition of the global atmosphere since 1978.There are 13 active stations scattered around the world, including in California, Europe, Asia, and Australia. At each station, air inlets atop typically 30-foot-tall towers pull in air about 20 times per day, and researchers use automated instruments to analyze the atmospheric concentrations of more than 50 greenhouse and ozone-depleting gases. With stations around the world monitoring gases at such a high frequency, AGAGE provides a highly accurate way to identify which emissions might be rising and where these emissions may originate.When Fang began looking through AGAGE data, he noticed an increasing trend in the concentrations of chloroform around the world between 2010 and 2015. He also observed about three times the amount of atmospheric chloroform in the Northern Hemisphere compared to the Southern Hemisphere, suggesting that the source of these emissions stemmed somewhere in the Northern Hemisphere.Using an atmospheric model, Fang's collaborators on the paper estimated that between 2000 and 2010, global chloroform emissions remained at about 270 kilotons per year. However, this number began climbing after 2010, reaching a high of 324 kilotons per year in 2015. Fang observed that most stations in the AGAGE network did not measure substantial increases in the magnitude of spikes in chloroform, indicating negligible emission rises in their respective regions, including Europe, Australia, and the western United States. However, two stations in East Asia -- one in Hateruma, Japan, and the other in Gosan, South Korea -- showed dramatic increases in the frequency and magnitude of spikes in the ozone-depleting gas.The rise in global chloroform emissions seemed, then, to come from East Asia. To investigate further, the team used two different three-dimensional atmospheric models that simulate the movement of gases and chemicals, given global circulation patterns. Each model can essentially trace the origins of a certain parcel of air. Fang and his colleagues fed AGAGE data from 2010 to 2015 into the two models and found that they both agreed on chloroform's source: East Asia."We conclude that eastern China can explain almost all the global increase," Fang says. "We also found that the major chloroform production factories and industrialized areas in China are spatially correlated with the emissions hotspots. And some industrial reports show that chloroform use has increased, though we are not fully clear about the relationship between chloroform production and use, and the increase in chloroform emissions."Last year, researchers from the United Kingdom reported on the potential threat to the ozone layer from another very short-lived substance, dichloromethane, which, like chloroform, is used as a feedstock to produce other industrial chemicals. Those researchers estimated how both ozone and chlorine levels in the stratosphere would change with increasing levels of dichloromethane in the atmosphere.Fang and his colleagues used similar methods to gauge the effect of increasing chloroform levels on ozone recovery. They found that if concentrations remained steady at 2015 levels, the increase observed from 2010 to 2015 would delay ozone recovery by about five months. If, however, concentrations were to continue climbing as they have through 2050, this would set a complete healing of the ozone layer back by four to eight years.The fact that the rise in chloroform stems from East Asia adds further urgency to the situation. This region is especially susceptible to monsoons, typhoons, and other extreme storms that could give chloroform and other short-lived species a boost into the stratosphere, where they would eventually decompose into the chlorine that eats away at ozone."There's an unfortunate coherence between where chloroform is being emitted and where there are frequent storms that puncture the top of the troposphere and go into the stratosphere," Prinn says. "So, a bigger fraction of what's released in East Asia gets into the stratosphere than in other parts of the world."Fang and Prinn say that the study is a "heads-up" to scientists and regulators that the journey toward repairing the ozone layer is not yet over."Our paper found that chloroform in the atmosphere is increasing, and we identified the regions of this emission increase and the potential impacts on future ozone recovery," Fang says. "So future regulations may need to be made for these short-lived species.""Now is the time to do it, when it's sort of the beginning of this trend," Prinn adds. "Otherwise, you will get more and more of these factories built, which is what happened with CFCs, where more and more end uses were found beyond refrigerants. For chloroform, people will surely find additional uses for it."

Ozone Holes

December 13, 2018

https://www.sciencedaily.com/releases/2018/12/181213141527.htm

Snow over Antarctica buffered sea level rise during last century

new NASA-led study has determined that an increase in snowfall accumulation over Antarctica during the 20th century mitigated sea level rise by 0.4 inches. However, Antarctica's additional ice mass gained from snowfall makes up for just about a third of its current ice loss.

"Our findings don't mean that Antarctica is growing; it's still losing mass, even with the extra snowfall," said Brooke Medley, a glaciologist with NASA Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study, which was published in Nature Climate Change on Dec. 10. "What it means, however, is that without these gains, we would have experienced even more sea level rise in the 20th century."The polar ice sheets grow via snow accumulation and shrink through melting and the production of icebergs. Presently, both ice sheets are imbalanced -losing more ice annually than they are gaining- and their ice loss is estimated to be currently causing about a half of the observed sea level rise. Sea level adjusts to changes in snowfall, which modulates how much water is locked into the ice sheets.Snowfall is very difficult to measure over Antarctica. For starters, there are very few weather stations in the frozen continent, and most of them are installed along the coastline. Secondly, satellites have a hard time measuring snow from space -- they basically confuse the snow that's falling down with the snow that's already on the ground. Climate models struggle to replicate the total amount of snow that falls over Antarctica each year. So scientists often have to rely on ice cores, cylinders of ice drilled from the ice sheet whose layers store a trove of information; amongst it, how much snow fell in a certain year or decade. But drilling ice cores is logistically challenging, so they are sparse and do not cover the entire continent.Medley and her colleague, British Antarctic Survey's Elizabeth Thomas, reconstructed how much snow fell over the entire Antarctic continent and nearby islands from 1801 to 2000 using 53 ice cores and three atmospheric reanalyses -climate models informed by satellite observations. Ice cores are only point measurements of snow accumulation, but by comparing them to the reanalyses' simulations of Antarctic snowfall across the ice sheet, the researchers were able to determine the area of Antarctica each ice core was representative of.The scientists found that the distribution of ice cores gave a good coverage of most of Antarctica, with some gaps in portions of East Antarctica due to the fact that this area of the continent sees extremely little snowfall, making it difficult to measure."Antarctica is bigger than the contiguous United States. You wouldn't say that because you're in New York City and it's snowing, it must mean that it's also snowing in San Diego. It's the same with Antarctica; you can't just stand in one spot, take one measurement and say 'okay, I think I have a good handle on all of Antarctica.' It requires a lot of measurements," Medley said.Medley and Thomas found that snow accumulation increased over the 20th century by 0.04 inches per decade, and that rate more than doubled after 1979."From the ice cores we know that the current rate of change in snowfall is unusual in the context of the past 200 years," Thomas said.The researchers also investigated what caused the increase of snowfall and its distribution pattern over the ice sheet from 1901 to 2000. They found that it was consistent with a warming atmosphere, which holds more moisture, combined with changes in the Antarctic circumpolar westerly winds that are related to the ozone hole. A related paper published in Geophysical Research Letters on Dec. 10 confirms the relationship between stratospheric ozone depletion and increased snowfall over Antarctica."The fact that changes in westerly winds due to ozone depletion plays a role in Antarctic snow accumulation variability indicates that even this remote, uninhabited land has been affected by human activity," Medley said."The increased snowfall is a symptom of the same changes in atmospheric circulation that are causing the melt of Antarctic ice," Thomas said."Snowfall plays a critical role in Antarctic mass balance and it will continue to do so in the future," Medley said. "Currently it is helping mitigate ice losses, but it's not entirely compensating for them. We expect snowfall will continue to increase into the 21st century and beyond, but our results show that future increases in snowfall cannot keep pace with oceanic-driven ice losses in Antarctica."Medley hoped that their results will also help evaluate existing climate models so that ice sheet modelers can pick the most reliable ones to use for their predictions of how the Antarctic ice sheet will behave in the future.

Ozone Holes

December 10, 2018

https://www.sciencedaily.com/releases/2018/12/181210101923.htm

Ozone depletion increases Antarctic snowfall, partially mitigates ice sheet loss

Ozone layer depletion has increased snowfall over Antarctica in recent decades, partially mitigating the ongoing loss of the continent's ice sheet mass, new University of Colorado Boulder research finds.

The findings, published today in the journal "Calving icebergs and melting ice shelves have gotten lots of attention because they're the most visible impact of ongoing climate change to Antarctica," said Jan Lenaerts, lead author of the research and an assistant professor in CU Boulder's Department of Atmospheric and Oceanic Sciences. "But the input side of the equation, which is precipitation falling in the form of snow, hasn't drawn the same level of study."An ozone "hole," or a seasonal thinning of the ozone layer, forms above Antarctica in the austral summer, influencing atmospheric circulation and creating stronger circumpolar westerly winds.While previous research has outlined some aspects of the relationship between ozone depletion and the climate of the southern hemisphere, the new study co-authored by Lenaerts, Jeremy Fyke of Los Alamos National Laboratory and Brooke Medley of NASA's Goddard Space Flight Center Cryospheric Sciences Laboratory has analyzed the effect on Antarctica specifically.The results complement a separate NASA-led study, which was led by Medley and published today in the journal Nature Climate Change, which uses observations from ice cores to show that Antarctic snowfall has increased in the last 200 years and especially so in the past 30 years, suggesting that precipitation changes can be linked to human-made causes such as greenhouse gas emissions as well as the ozone hole.In order to pinpoint the effect of ozone loss on Antarctic snowfall, Lenaerts and his colleagues compared two sets of eight climate modeling simulations, one set with observed ozone levels and one set with ozone values kept constant at levels before the ozone hole started, allowing the researchers to isolate the signal relative to natural climate variability.The comprehensive analysis, which encompassed the years 1955-2005, revealed increased Antarctic precipitation during the austral summer that can be attributed to lower levels of stratospheric ozone, and which has in part buffered ice sheet mass loss.Paradoxically, while the results suggest that ozone depletion (previously the focus of global conservation efforts such as the 1987 Montreal Protocol) helps to partially mitigate sea level rise by increasing Antarctic precipitation, those mass gains have been more than offset by increasing iceberg calving and melting."The pace at which snowfall is increasing is not keeping up with the ocean-induced losses," Lenaerts said. "The Antarctic Ice Sheet is still losing mass."

Ozone Holes

December 7, 2018

https://www.sciencedaily.com/releases/2018/12/181207112746.htm

How ice particles promote the formation of radicals

The production of chlorofluorocarbons, which damage the ozone layer, has been banned as far as possible. However, other substances can also tear holes in the ozone layer in combination with ice particles, such as those found in clouds. Researchers at Ruhr-Universität Bochum, the University of Duisburg-Essen and Friedrich-Alexander-Universität Erlangen-Nürnberg have discovered a possible mechanism for this. They describe it in the journal

The work was part of a long-standing cooperation between the teams from Bochum, Duisburg-Essen, and Erlangen-Nuremberg led by Professor Karina Morgenstern, Dr. Cord Bertram, Professor Uwe Bovensiepen and Professor Michel Bockstedte, which is currently being continued within the framework of the cluster of excellence Ruhr Explores Solvation, or Resolv for short.Chemical processes can significantly influence the weather, the climate and the composition of the atmosphere. Cosmic rays or UV light provide the energy to split chemical compounds. In the case of bromine, chlorine or fluorine compounds, radicals, i.e. particularly reactive molecules, are formed. These attack the ozone molecules and can trigger chain reactions in the ozone layer. An earlier laboratory study had shown that ice particles with a silver core can promote such reactions. The team investigated the mechanism behind this effect in the current study.In the laboratory, the scientists produced tiny ice particles and analysed how certain compounds containing chlorine or bromine interacted with them. They condensed the ice particles onto copper. In nature, mineral dust particles, among other things, form condensation nuclei for the ice particles.Using microscopic and spectroscopic methods, they observed that the molecules preferentially attached themselves to defects in the ice structure. The surrounding water molecules of the ice structure then reoriented themselves and hydrogenated the molecules. This, in turn, made it easier to ionise the molecules in the experiment.The researchers irradiated the ice crystals with the attached molecules using UV light, which excited electrons in the ice particles in the vicinity of the molecules. These excited electrons ionised the chlorine and bromobenzene molecules. Through ionisation, the molecules disintegrated into organic residues and highly reactive chlorine and bromine radicals."The mechanism could explain what happens when UV light hits mineral-contaminated ice," says Cord Bertram. "Our results could thus help to understand the fundamental processes behind phenomena such as ozone holes."

Ozone Holes

November 30, 2018

https://www.sciencedaily.com/releases/2018/11/181130153849.htm

Greenhouse gas 'detergent' recycles itself in atmosphere

A simple molecule in the atmosphere that acts as a "detergent" to break down methane and other greenhouse gases has been found to recycle itself to maintain a steady global presence in the face of rising emissions, according to new NASA research. Understanding its role in the atmosphere is critical for determining the lifetime of methane, a powerful contributor to climate change.

The hydroxyl (OH) radical, a molecule made up of one hydrogen atom, one oxygen atom with a free (or unpaired) electron is one of the most reactive gases in the atmosphere and regularly breaks down other gases, effectively ending their lifetimes. In this way OH is the main check on the concentration of methane, a potent greenhouse gas that is second only to carbon dioxide in contributing to increasing global temperatures.With the rise of methane emissions into the atmosphere, scientists historically thought that might cause the amount of hydroxyl radicals to be used up on the global scale and, as a result, extend methane's lifetime, currently estimated to be nine years. However, in addition to looking globally at primary sources of OH and the amount of methane and other gases it breaks down, this new research takes into account secondary OH sources, recycling that happens after OH breaks down methane and reforms in the presence of other gases, which has been observed on regional scales before."OH concentrations are pretty stable over time," said atmospheric chemist and lead author Julie Nicely at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "When OH reacts with methane it doesn't necessarily go away in the presence of other gases, especially nitrogen oxides (NO and NONitrogen oxides are one set of several gases that contribute to recycling OH back into the atmosphere, according to Nicely's research, published in the OH in the atmosphere also forms when ultraviolet sunlight reaches the lower atmosphere and reacts with water vapor (HShe and her team found that, individually, the tropical widening effect and OH recycling through reactions with other gases each comprise a relatively small source of OH, but together they essentially replace the OH used up in the breaking down of methane."The absence of a trend in global OH is surprising," said atmospheric chemist Tom Hanisco at Goddard who was not involved in the research. "Most models predict a 'feedback effect' between OH and methane. In the reaction of OH with methane, OH is also removed. The increase in NOUltimately, Nicely views the results as a way to fine-tune and update the assumptions that are made by researchers and climate modelers who describe and predict how OH and methane interact throughout the atmosphere. "This could add clarification on the question of will methane concentrations continue rising in the future? Or will they level off, or perhaps even decrease? This is a major question regarding future climate that we really don't know the answer to," she said.

Ozone Holes

November 12, 2018

https://www.sciencedaily.com/releases/2018/11/181112191810.htm

Alpine ice shows three-fold increase in atmospheric iodine

Analysis of iodine trapped in Alpine ice has shown that levels of atmospheric iodine have tripled over the past century, which partially offsets human-driven increases in the air pollutant, ozone.

The study showed, however that, although iodine can destroy 'bad' ozone, there isn't enough to counter all of the production. Researchers say it is now important to include iodine data in climate models that predict future global environmental outcomes.Analysis of the Alpine ice, by scientists at the University of York, Université Grenoble Alpes, and Desert Research Institute, shows that iodine concentration began to increase after the Second World War following the growth in motor vehicles and electricity generation.Nitrogen oxide emissions from vehicles and power plants since the 1950s increases surface ozone, and this reacts with chemicals in seawater to release more iodine into the atmosphere, which partially, but not completely, destroys some of these harmful gases.Professor Lucy Carpenter, from the University of York's Department of Chemistry, said: "Iodine's role in human health has been recognised for some time - it is an essential part of our diets."Its role in climate change and air pollution, however, has only been recently recognised, and up until now, there have been no historical records of iodine in populated regions such as Europe."Due to the difficulty in accessing this kind of data, the impact of iodine in the atmosphere is not currently a feature of the climate or air quality models that predict future global environmental changes."The study in the European Alps has now provided new long-term insight into the delicate balance of ozone in the atmosphere.Ozone in the lower atmosphere acts as an air pollutant and greenhouse gas, but ozone is also the main driver of iodine emissions from the ocean. Once released into the atmosphere iodine acts to destroy this 'bad' ozone.The more ozone humans produce, the more iodine is released from the ocean which can then help destroy the ozone produced by humans. This means that iodine levels in the ocean can, at least partially, act to keep ozone gases in the lower atmosphere in check, but there isn't enough to counter all of the production.Dr Tomás Sherwen, from the University of York's Department of Chemistry, said: "When we look at the concentrations of iodine over time, we can see that it was fairly steady during the industrial revolution."However as more cars appeared on the roads in the post-war period, we get more emissions of nitrogen oxides causing more ozone in the atmosphere and therefore more iodine."Surface ozone concentrations have stabilised over much of Europe and the Atlantic ocean, although are still growing over other regions."We can now start to think about factoring in our knowledge of iodine chemistry into climate and air quality models to help us better predict what the future of our atmosphere will look like around the globe."The research is published in the journal  

Ozone Holes

November 6, 2018

https://www.sciencedaily.com/releases/2018/11/181106150429.htm

Plasma-based system provides radical new path for water purification

Many of today's methods of purifying water rely on filters and chemicals that need regular replenishing or maintenance. Millions of people, however, live in areas with limited access to such materials, leading the research community to explore new options of purifying water in using plasmas. Many plasma-based approaches are expensive, but a new class of plasma devices may change that.

Researchers at the University of Alabama in Huntsville have been studying a new type of plasma generator for water purification. The new generator pulses voltage signals to ionize gas at atmospheric pressure and produce many useful byproducts, including hydroxyl radicals, which cause a cascade of reactions that lead to purer water samples."We're finding ways to speed up the purification process," said Ryan Gott, a doctoral candidate in aerospace engineering at UAH who will present the research next week at the American Physical Society 71st Annual Gaseous Electronics Conference and the 60th Annual meeting of the APS Division of Plasma Physics, which will take place Nov. 5-9 at the Oregon Convention Center in Portland."In theory, if this technology can be developed in a real-world, practical system, it would be able to purify water at lower costs than current methods can," Gott said.While the term "plasma" conjures images of superhot solar jets traveling through space, most plasma-based water purification approaches work through plasma's ability to generate reactive free radicals, rendering many compounds in the water inert. The plasma and ensuing chemical reactions release energy and chemical species that can kill even tough microcystin bacteria, one culprit in algal blooms that lurk in our water supply."The pulses are so fast that it doesn't change the temperature of the water," Gott said. "You can touch our plasma jet with your hand."Unlike more common, ozone-producing plasma purifiers, the new device relies on the production of hydroxyl radicals. This method will hopefully sidestep some of the hurdles that have hampered ozone-based counterparts, namely high power consumption and challenges keeping excessive heat in check.Using optical emission spectroscopy, the UAH researchers have been able to compare how different factors play a role in producing more hydroxyl radicals from their plasma device. Increasing voltage, for example, appears to have the biggest effect on output, followed by increasing the frequency of the pulses.Right now, the device is limited to 10 kilovolts, but the researchers are hoping to see what higher voltage could mean down the road.Gott said after the group continues to better understand the mechanisms behind how the plasma interacts with water, he hopes to scale up the technology for point-of-use applications."The end goal is to develop something that can be mass-produced and distributed to places that need it the most," he said.

Ozone Holes

November 2, 2018

https://www.sciencedaily.com/releases/2018/11/181102180808.htm

Ozone hole modest despite optimum conditions for ozone depletion

The ozone hole that forms in the upper atmosphere over Antarctica each September was slightly above average size in 2018, NOAA and NASA scientists reported today.

Colder-than-average temperatures in the Antarctic stratosphere created ideal conditions for destroying ozone this year, but declining levels of ozone-depleting chemicals prevented the hole from as being as large as it would have been 20 years ago."Chlorine levels in the Antarctic stratosphere have fallen about 11 percent from the peak year in 2000," said Paul A. Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "This year's colder temperatures would have given us a much larger ozone hole if chlorine was still at levels we saw back in the year 2000."According to NASA, the annual ozone hole reached an average area coverage of 8.83 million square miles (22.9 square kilometers) in 2018, almost three times the size of the contiguous United States. It ranks 13th largest out of 40 years of NASA satellite observations. Nations of the world began phasing out the use of ozone-depleting substances in 1987 under an international treaty known as the Montreal Protocol.The 2018 ozone hole was strongly influenced by a stable and cold Antarctic vortex -- the stratospheric low pressure system that flows clockwise in the atmosphere above Antarctica. These colder conditions -- among the coldest since 1979 -- helped support formation of more polar stratospheric clouds, whose cloud particles activate ozone-destroying forms of chlorine and bromine compounds.In 2016 and 2017, warmer temperatures in September limited the formation of polar stratospheric clouds and slowed the ozone hole's growth. In 2017, the ozone hole reached a size of 7.6 million square miles (19.7 square kilometers) before starting to recover. In 2016, the hole grew to 8 million square miles (20.7 square kilometers).However, the current ozone hole area is still large compared to the 1980s, when the depletion of the ozone layer above Antarctica was first detected. Atmospheric levels of human-made ozone-depleting substances increased up to the year 2000. Since then, they have slowly declined but remain high enough to produce significant ozone loss.NOAA scientists said colder temperatures in 2018 allowed for near-complete elimination of ozone in a deep, 3.1-mile (5-kilometer) layer over the South Pole. This layer is where the active chemical depletion of ozone occurs on polar stratospheric clouds. The amount of ozone over the South Pole reached a minimum of 104 Dobson units on Oct. 12 -- making it the 12th lowest year out of 33 years of NOAA ozonesonde measurements at the South Pole, according to NOAA scientist Bryan Johnson."Even with this year's optimum conditions, ozone loss was less severe in the upper altitude layers, which is what we would expect given the declining chlorine concentrations we're seeing in the stratosphere," Johnson said.A Dobson unit is the standard measurement for the total amount of ozone in the atmosphere above a point on Earth's surface, and it represents the number of ozone molecules required to create a layer of pure ozone 0.01 millimeters thick at a temperature of 32 degrees Fahrenheit (0 degrees Celsius) at an atmospheric pressure equivalent to Earth's surface. A value of 104 Dobson units would be a layer that is 1.04 millimeters thick at the surface, less than the thickness of a dime.Prior to the emergence of the Antarctic ozone hole in the 1970s, the average amount of ozone above the South Pole in September and October ranged from 250 to 350 Dobson units.Ozone comprises three oxygen atoms and is highly reactive with other chemicals. In the stratosphere, roughly 7 to 25 miles (about 11 to 40 kilometers) above Earth's surface, a layer of ozone acts like sunscreen, shielding the planet from ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and damage plants. Ozone can also be created by photochemical reactions between the Sun and pollution from vehicle emissions and other sources, forming harmful smog in the lower atmosphere.NASA and NOAA use three complementary instrumental methods to monitor the growth and breakup of the ozone hole each year. Satellite instruments like the Ozone Monitoring Instrument on NASA's Aura satellite and the Ozone Mapping Profiler Suite on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite measure ozone across large areas from space. The Aura satellite's Microwave Limb Sounder also measures certain chlorine-containing gases, providing estimates of total chlorine levels.The total amount of ozone in the atmosphere is exceedingly small. All of the ozone in a column of the atmosphere extending from the ground to space would be 300 Dobson units, approximately the thickness of two pennies stacked one on top of the other.NOAA scientists monitor the thickness of the ozone layer and its vertical distribution above the South Pole by regularly releasing weather balloons carrying ozone-measuring "sondes" up to 21 miles (~34 kilometers) in altitude, and with a ground-based instrument called a Dobson spectrophotometer.

Ozone Holes

October 30, 2018

https://www.sciencedaily.com/releases/2018/10/181030134330.htm

Reducing methane emissions can play a key role in reducing ozone worldwide

Methane (CH4) is the main ingredient in natural gas. It is the second most important greenhouse gas (GHG) after carbon dioxide (CO

Ozone has harmful effects for people, ecosystems and agricultural productivity. It is a so-called "short-lived climate forcer." This term refers to pollutants that remain in the atmosphere for a much shorter period of time than COThe life span of short-lived climate pollutants is usually less than 15 years, unlike COSince the pre-industrial era, methane concentrations have more than doubled. And after a period of stagnation, they are increasing again since the last decade."Worldwide, methane emissions increased by 17% between 1990-2012, compared to a 53% increase in COIf nothing is done about reducing methane emissions worldwide, they could cause between 40,000 and 90,000 more premature deaths globally by 2050, compared to the present situation.A new JRC study shows that the human-made methane emissions are on a non-sustainable path, but that there are cheap and even profitable options to reduce emissions in a relatively short time frame."About 60% of the global methane emissions originate from agriculture, landfills and wastewater, and the production and transport of fossil fuels. Targeting these three sectors can bring a significant reduction in the overall methane emissions and ozone concentrations globally," said Rita who presented the JRC report today at the WHO global conference on air pollution and health.The JRC report shows that there is a substantial global mitigation potential in these three sectors. In particular, important emissions reductions can be obtained by:Scientists also note that there are big differences in the methane emissions from the waste and fossil fuel production sectors between developed and developing countries. Investing in efforts to align developing regions with the Sustainable Development Goals (SDGs) can unlock a huge potential for emissions reduction.The EU is spearheading global efforts to fight climate change and reduce GHG emissions. The bloc is set to meet its 2020 target to reduce GHG emissions by at least 20% compared to 1990 -- and has raised this target to at least 40% by 2030. The 2030 target is the basis of the EU's commitment to the 2015 Paris Agreement, and the legislative framework for implementing it has already been adopted.In its Declaration on the Review of Methane Emissions, the European Commission also stated its intention to review methane emissions in the context of assessing options to further reduce ozone concentrations in the EU, and to promote methane reductions internationally.However, Europe's contribution to global CH4 emissions is currently only about 6%. Reducing methane emissions in Europe only is not enough to make a difference. Global cooperation to reduce methane emissions is essential -- not only for the climate but also to prevent air pollution.International climate agreements are thus an important means to reduce CH4 emissions. Reaching the emission reduction targets included in the Paris Agreement would reduce global CH4 emissions substantially. This would mean that the exposure of the global and European populations to ozone would remain at the 2010 levels.

Ozone Holes

October 29, 2018

https://www.sciencedaily.com/releases/2018/10/181029131003.htm

Coal power plant regulations neglect a crucial pollutant

Cleaning up or replacing coal-fired power plants that lack sulfur pollution controls could help Texans breathe cleaner, healthier air, according to researchers at Rice University.

A study led by environmental engineer Daniel Cohan analyzed models that measure the effects of emissions from 13 coal plants in Texas. Along with their conclusions on the modeling systems themselves, they found residents downwind of coal plants would be far better off today had the state focused on cutting particle-forming sulfur dioxide emissions in addition to those that cause ozone."Texas has more unscrubbed coal plants than anywhere in the country and it's causing a substantial amount of air pollution damage and impacts on our health," Cohan said. "What I found eye-opening in this study is that most of the health damage is coming from particulate matter, but most of Texas' focus on air pollution has been on ozone smog. It's a real dichotomy where the standard we violate is ground-level ozone, but the biggest cause of damage is particulate matter."The study appears in the Three of the state's coal plants have closed in 2018, but the effects of all 13 are represented in data collected from 2012 to 2017 and used by Cohan and co-authors Brian Strasert, a Rice alumnus now at GSI Environmental in Houston, and undergraduate student Su Chen Teh.The researchers wrote that as coal power gets more expensive and natural gas and renewables like wind and solar energy advance, companies seem more likely to close plants based solely on economic considerations.They also point out the state missed an opportunity to accelerate the benefits that would have come with enforcement of the Obama-era regional haze plan. That would have cut emissions of sulfur dioxide, a contributor to airborne particulate matter -- invisible particles less than 2.5 microns in diameter -- at eight of the highest-emitting plants. Instead, in 2017, the Environmental Protection Agency replaced the plan with a cap-and-trade program."That doesn't mean the plants will get worse," Cohan said. "It just means the plants that should have been forced to clean up or close down have gotten a get-out-of-jail-free card."The researchers noted that according to EPA statistics, Texas power plants emit more than twice as much sulfur dioxide as second-ranked Missouri. The problem, Cohan said, is that even when particulate levels meet current standards, they are still health hazards, especially to those directly downwind of the plants."We know the higher the particulate matter levels, the more people die, both on a short-term correlation -- when particulate matter levels are high one day, death rates are higher over the next few days -- and also over long-term studies," he said. "When epidemiologists study people across 10 or 20 years, they find that life expectancies are better in places that have very low levels of particulate matter than places that have high levels."Particulate matter is the deadliest of all air pollutants, and it's not just causing deaths in the way that you might think," Cohan said. "It's not only by respiratory diseases, but it's also causing increases in rates of heart attacks and strokes. These particles are small enough to pass through the alveoli and enter the bloodstream. That lets them cause damage on all aspects of our bodily systems."That was really striking to me," he said. "Because Texas meets the particulate matter standard, it hasn't prioritized cleaning up sulfur anywhere near the extent that it's cleaning up nitrogen pollution. We're allowing plants to emit levels of pollution that haven't been allowed since the 1970s. They're still operating today, because the state and EPA have failed since 2009 to finalize a regional haze plan."Cohan said the EPA continues to take comments on its plan for Texas.The paper also showed that recent, simple atmospheric models that help researchers quickly compute the health effects from pollution compare favorably with a more complicated state-of-the-art model. "That suggests we can take easier approaches to more quickly estimate the impacts of these plants," Cohan said.In time, he said, coal plants seem likely to close either because air pollution standards will be enforced across the board or because renewables like wind and solar make them unprofitable."The key message of our paper," Cohan said, "is that delay has very real costs for us in Texas."

Ozone Holes

October 26, 2018

https://www.sciencedaily.com/releases/2018/10/181026102600.htm

Location of large mystery source of banned ozone depleting substance uncovered

The compound, carbon tetrachloride, contributes to the destruction of the Earth's ozone layer, which protects us from harmful ultraviolet radiation.

As a result, the production of carbon tetrachloride has been banned throughout the world since 2010 for uses that will result in its release to the atmosphere. However, recent studies have shown that global emissions have not declined as expected, with about 40,000 tonnes still being emitted each year.The origin of these emissions has puzzled researchers for many years.Alongside collaborators from South Korea, Switzerland, Australia and the USA, researchers at the University of Bristol aimed to quantify emissions from eastern Asia.To do this, they used ground-based and airborne atmospheric concentration data from near the Korean peninsula and two models that simulate the transport of gases through the atmosphere.Their results, published in the journal Lead author, Dr Mark Lunt, from the University of Bristol's School of Chemistry, said: "Our results show that emissions of carbon tetrachloride from the eastern Asia region account for a large proportion of global emissions and are significantly larger than some previous studies have suggested."Not only that, but despite the phase out of carbon tetrachloride production for emissive use in 2010, we found no evidence for a subsequent decrease in emissions."In fact, emissions from certain regions may have increased slightly since 2010. The results from the study show the emergence of a new source of emissions from the Shandong province of China after 2012.Whilst the results of this and earlier studies in Europe and the USA now explain a large part of the global distribution of carbon tetrachloride emissions, there are still large gaps in our knowledge. Furthermore, recent reports have suggested that very large amounts of this gas may be emitted inadvertently during the production of other chemicals such as chlorine.Dr Matt Rigby, Reader in Atmospheric Chemistry at the University of Bristol and co-author, said: "Our work shows the location of carbon tetrachloride emissions. However, we don't yet know the processes or industries that are responsible. This is important because we don't know if it is being produced intentionally or inadvertently."He also added: "There are areas of the world such as India, South America and other parts of Asia, where emissions of ozone-depleting gases may be ongoing, but detailed atmospheric measurements are lacking."It is hoped that this work can now be used by scientists and regulators to identify the cause of these emissions from eastern Asia. Ultimately, if these emissions can be avoided, it would hasten the recovery of the stratospheric ozone layer.Dr Lunt said: "Studies such as this show the importance of continued monitoring of ozone-depleting gases. There is a temptation to see ozone depletion as a problem that has been solved. But the monitoring of human-made ozone-depleting gases in the atmosphere is essential to ensure the continued success of the phase-out of these compounds."

Ozone Holes

October 25, 2018

https://www.sciencedaily.com/releases/2018/10/181025083955.htm

Air pollution leads to millions of ER visits for asthma attacks worldwide

Nine to 33 million visits to the emergency room (ER) for asthma worldwide may be triggered by breathing in air polluted by ozone or fine particulate matter -- pollutants that can enter the lung's deep airways, according to a study published today.

Scientists have long known that breathing in air sullied by car emissions and other pollutants could trigger asthma attacks. However, the new study is the first to quantify air pollution's impact on asthma cases around the globe."Millions of people worldwide have to go to emergency rooms for asthma attacks every year because they are breathing dirty air," said Susan C. Anenberg, PhD, MS, lead author of the study and an Associate Professor of Environmental and Occupational Health at the George Washington University Milken Institute School of Public Health (Milken Institute SPH). "Our findings suggest that policies aimed at cleaning up the air can reduce the global burden of asthma and improve respiratory health around the world."Asthma is the most prevalent chronic respiratory disease worldwide, affecting about 358 million people. The new findings, published in the journal Anenberg and her team first looked at emergency room visits for asthma in 54 countries and Hong Kong, and then combined that information with epidemiological exposure-response relationships and global pollution levels derived from satellites orbiting the earth.The new research suggests that:To estimate the global levels of pollution for this study, the researchers turned to atmospheric models, ground monitors and satellites equipped with remote-sensing devices."The value of using satellites is that we were able to obtain a consistent measure of air pollution concentrations throughout the world," said Daven Henze, who is the principal investigator on the project and an associate professor for the University of Colorado Boulder. "This information allowed us to link the asthma burden to air pollution even in parts of the world where ambient air quality measurements have not been available."Countries like India and China may be harder hit by the asthma burden because they have large populations and tend to have fewer restrictions on factories belching smoke and other sources of pollution, which can then trigger breathing difficulties, the authors said.Approximately 95 percent of the world's population lives in places with unsafe air. Previously, the Global Burden of Disease Study focused on quantifying the impacts of air pollution on heart disease, chronic respiratory disease, lung cancer, and lower respiratory infections -- finding that fine particulate matter and ozone were associated with 4.1 million and 230,000 premature deaths in 2016, respectively."We know that air pollution is the leading environmental health risk factor globally," Anenberg said. "Our results show that the range of global public health impacts from breathing dirty air are even more far reaching -- and include millions of asthma attacks every year."To reduce the global burden caused by asthma, Anenberg suggests that policymakers aggressively target known sources of pollution such as ozone, fine particulate matter and nitrogen dioxide. She says policies that result in cleaner air might reduce not just the asthma burden but other health problems as well.One way to reduce pollutants quickly would be to target emissions from cars, especially in big cities. Such policies would not only help people with asthma and other respiratory diseases but it would help everyone breathe a little easier, she said.Support for the study was provided by the NASA Health and Air Quality Applied Science Team, NASA Aura ACMAP, the Stockholm Environment Institute Low Emissions Development Pathways Initiative, and the Global Environment Research Fund of the Japan Ministry of the Environment.

Ozone Holes

October 17, 2018

https://www.sciencedaily.com/releases/2018/10/181017124448.htm

Substantial changes in air pollution across China during 2015 to 2017

The first detailed analysis of air pollution trends in China reveals a 20 per cent drop in concentrations of particulate pollution over the last three years (2015-2017).

A study by the University of Leeds has examined measurements from more than 1600 locations in China and found that more than 50 per cent of the locations showed a significant decrease in concentrations of sulphur dioxide and fine particulates that make up a large portion of air pollution.The team used datasets from 2015 to 2017 consisting of hourly assessments of concentrations of Nitrogen Dioxide (NOThe hourly data was used to calculate monthly averages and determine overall concentration levels as well as which regions of China have the highest and lowest concentrations. The data was then used to assess whether pollutant concentrations had changed over the 2015 to 2017 period. The team found that concentrations of PM2.5 fell by 7.2% per year over this period and concentrations of SO2 fell by 10.3% per year. In contrast, O3 concentrations increased by 5% per year.Study co-author Professor Dominick Spracklen, from the School of Earth and Environment at Leeds, said: "Rapid economic growth and large increases in emissions has led to serious air quality issues across China. One of the most dangerous components of air pollution is fine particulate matter that measures less than the width of a human hair. These particles can penetrate deeply into the lungs causing serious health complications. Exposure to these particles is estimated to cause more than 1 million deaths across China each year."In response the Chinese government introduced policies to reduce emissions and set ambitious targets to limit the amount of particulates in the atmosphere. This is the first detailed assessment as to whether these policies are having an impact."Ben Silver, study lead author and post graduate researcher at Leeds, said "Our work shows rapid and extensive changes in air pollution right across China. In particular it is encouraging to see that levels of fine particulate matter have fallen rapidly in the last few years."While more research is needed to fully assess what is driving the trends we've uncovered here, particularly what is causing the widespread increase in ozone concentrations, we can see that China's emissions control policies seem to be on the right track."

Ozone Holes

October 11, 2018

https://www.sciencedaily.com/releases/2018/10/181011103623.htm

Long-term exposure to ozone has significant impacts on human health

A new study has utilized a novel method to estimate long-term ozone exposure and previously reported epidemiological results to quantify the health burden from long-term ozone exposure in three major regions of the world.

The research, by Duke University (USA) and the University of York (UK), estimates that 266,000 (confidence interval: 186,000-338,000) premature mortalities across Europe, the USA and China in 2015 were attributable to long-term exposure to ozone (OIt publishes today in Karl Seltzer, from Duke University, is the study's lead author. He said: "The there is strong epidemiological and toxicological evidence linking ambient ozone exposure to adverse health effects."Historically, much of the previous research focussed on the short-term impacts. We utilized results from the growing body of evidence that links long-term OTo do this, the researchers used 2015 data from ground-based monitoring networks in the USA, Europe and China to estimate long-term OMr Seltzer said: "Global estimates of OInterestingly, the team's observationally-derived data shows smaller human-health impacts when compared to prior modelling results.Mr Seltzer explained: "This difference is due to small biases in modelled results. These small biases are subsequently amplified by non-linear exposure-response curves. This highlights the importance of accurately estimating long-term O"First, health impacts attributable to long-term O"Second, results from the newest ACS CPS-II cohort analysis suggest that O"Finally, these results also highlight the importance of accurately estimating O

Ozone Holes

October 9, 2018

https://www.sciencedaily.com/releases/2018/10/181009210733.htm

Air pollution may be linked to heightened mouth cancer risk

High levels of air pollutants, especially fine particulate matter (PM2.5) and to a lesser extent, ozone, may be linked to a heightened risk of developing mouth cancer, suggests the first study of its kind, published online in the

The number of new cases, and deaths from, mouth cancer is increasing in many parts of the world. Known risk factors include smoking, drinking, human papilloma virus, and in parts of South East Asia, the chewing of betel quid ('paan'), a mix of ingredients wrapped in betel leaf.Exposure to heavy metals and emissions from petrochemical plants are also thought to be implicated in the development of the disease, while air pollution, especially PM2.5, is known to be harmful to respiratory and cardiovascular health.To find out if air pollutants might have a role in the development of mouth cancer, the researchers mined national cancer, health, insurance, and air quality databases.They drew on average levels of air pollutants (sulphur dioxide, carbon monoxide, ozone, nitrogen monoxide, nitrogen dioxide, and varying sizes of fine particulate matter), measured in 2009 at 66 air quality monitoring stations across Taiwan.In 2012-13, they checked the health records of 482,659 men aged 40 and older who had attended preventive health services, and had provided information on smoking/betel quid chewing.Diagnoses of mouth cancer were then linked to local area readings for air pollutants taken in 2009.In 2012-13, 1617 cases of mouth cancer were diagnosed among the men. Unsurprisingly, smoking and frequent betel quid chewing were significantly associated with heightened risk of a diagnosis.But so too were high levels of PM2.5. After taking account of potentially influential factors, increasing levels of PM2.5 were associated with an increasing risk of mouth cancer.When compared with levels below 26.74 ug/m3, those above 40.37 ug/ m3 were associated with a 43 per cent heightened risk of a mouth cancer diagnosis.A significant association was also observed for ozone levels below 28.69-30.97 parts per billion.This is an observational study, and as such, can't establish cause. And there are certain caveats to consider, say the researchers. These include the lack of data on how much PM2.5 enters the mouth, or on long term exposure to this pollutant.Nor is it clear how air pollutants might contribute to mouth cancer, they acknowledge, and further research would be needed to delve further into this.But some of the components of PM2.5 include heavy metals, as well as compounds such as polycyclic aromatic hydrocarbons-known cancer causing agents-they say.And the smaller diameter, but larger surface area, of PM2.5 means that it can be relatively easily absorbed while at the same time potentially wreaking greater havoc on the body, they suggest."This study, with a large sample size, is the first to associate oral cancer with PM2.5...These findings add to the growing evidence on the adverse effects of PM2.5 on human health," they conclude.

Ozone Holes

September 17, 2018

https://www.sciencedaily.com/releases/2018/09/180917153615.htm

Tropics are widening as predicted by climate models, research finds

Scientists have observed for years that Earth's tropics are widening in connection with complex changes in climate and weather patterns. But in recent years, it appeared the widening was outpacing what models predicted, suggesting other factors were at work.

A new paper co-authored by Indiana University Bloomington researcher Paul Staten, however, finds that the most up-to-date models and the best data match up reasonably well."If we compare the observed trends of how the tropics have widened to modeling trends, it's actually not outside of what the models predict," said Staten, assistant professor of atmospheric sciences in the College of Arts and Sciences.Staten is an affiliated researcher with the IU Environmental Resilience Institute, which was established under Prepared for Environmental Change, the second initiative funded by the university's Grand Challenges Program.The paper, "Re-examining Tropical Expansion," was published in the journal Staten said the research should add confidence to predictions based on current climate models."Climate change should continue to expand the tropics over the next several decades," he said. "But the expansion may not continue at the rapid rate we've seen; at times it may even temporarily contract."The authors conclude that the tropics have been widening at an average rate of about 0.2 degrees latitude, or about 17 miles, per decade in both the Northern and Southern hemispheres. The rate varies widely from year to year and from location to location.Widening of the tropics is important because it could be associated with severe changes in climate, Staten said. The world's hot, dry deserts tend to be located in bands along the northern and southern edges of the tropics, so widening of the tropics could lead to expansion of the subtropical deserts. At sea, the edges of the tropics are zones of high salinity and low marine productivity.About half of the world's population lives in or near subtropical semi-arid climate zones, the researchers write, so changes in the subtropical climate could affect billions of people.The researchers focus on five factors that may influence the widening of the tropics:Given the complexity of the factors, the authors say, it is difficult for now to tease out differences in natural and human-caused influences on the widening of the tropics. But if greenhouse gas emissions and pollution continue to increase, they write, human causes will become more obvious.

Ozone Holes

September 6, 2018

https://www.sciencedaily.com/releases/2018/09/180906123406.htm

Protection for the ozone layer: Sugar molecules bind harmful CFCs

Researchers at Johannes Gutenberg University Mainz (JGU) and Aschaffenburg University of Applied Sciences have managed to make a breakthrough when it comes to dealing with the extremely ozone-depleting chlorofluorocarbon Freon 11. Their findings could make a major contribution to protecting the endangered ozone layer.

Freon 11 is a chlorofluorocarbon (CFC). These substances were previously used, among other things, as coolants in refrigerators and as foaming agents for polyurethane foams. In the 1970s scientists realized that CFCs were damaging the protective ozone layer in the upper atmosphere and were also responsible for the appearance of the ozone hole. In addition, Freon 11 is 4,750 times more potent than carbon dioxide as a greenhouse gas, additionally contributing to global warming.Although the Montreal Protocol banned the production and trade of this CFC in the late 1980s, it is still released today when refrigerators are recycled and is even traded on the black market. The ozone-depleting substance has also recently been the subject of repeated scientific and media attention. A study published in the journal In their paper in the journal In addition, the research teams at Mainz and Aschaffenburg have been able to transfer this concept to an optical sensor device, making it possible to detect low concentrations of Freon 11 quickly and reliably.

Ozone Holes

August 29, 2018

https://www.sciencedaily.com/releases/2018/08/180829115557.htm

China is hot spot of ground-level ozone pollution

In China, people breathe air thick with the lung-damaging pollutant ozone two to six times more often than people in the United States, Europe, Japan, or South Korea, according to a new assessment. By one metric -- total number of days with daily maximum average ozone values (8-hour average) greater than 70 ppb -- China had twice as many high ozone days as Japan and South Korea, three times more than the United States, and six times more than Europe.

"We find that in the most populous urban regions of eastern and central China, there are more than 60 days in a calendar year with surface ozone levels exceeding the Chinese national ozone air quality standard," said Lin Zhang of Peking University, lead author of the study in the current issue of "China has become a hot spot of present-day surface ozone pollution," said Owen Cooper, a co-author on the research paper and a CIRES scientist working in NOAA's Chemical Sciences Division. "Human and vegetation exposure in China is greater than in other developed regions of the world with comprehensive ozone monitoring."Many countries regulate ozone because of the damage the pollutant does to plants and people.In the United States, for example, the current health-based standard for ground-level ozone, set by the U.S. Environmental Protection Agency, is 70 ppb (based on the maximum daily 8-hour average). The Chinese national ozone air quality standard is a daily maximum 8-hour average greater than 160 micrograms per cubic meter, equivalent to about 80 ppb.Ground level ozone is most commonly formed when volatile organic compounds and nitrogen oxides react in the atmosphere in the presence of sunlight. The burning of fossil fuels and biomass burning (from crop clearing or forest fires) are major sources of volatile organic compounds and nitrogen oxides. Since the 1990s, tighter controls on emissions of those ingredients have lessened ozone pollution in many European and U.S. cities. But the extent of surface ozone pollution in China hasn't been widely recognized, in part because there were so few Chinese monitoring sites before 2012, according to the researchers.For this study, the researchers used data from a relatively new network of 1,600 ozone monitors in China and a massive new global ozone database to quantify ozone levels in China and compare those to the levels in other countries.The new report shows that China has higher ozone pollution levels than all nations with ozone monitors, including the United States, Europe, Japan, and South Korea. Every ozone metric the researchers looked at rose continuously in China over the last five years. "We found the largest increases in ozone exposure in eastern and central China, especially in the most populous areas. These results indicate an increasing severity of human and crop/ecosystem ozone exposure across China," said Xiao Lu in Zhang's group, first author of the study.In fact, present-day ozone levels in major Chinese cities are comparable to U.S. levels in the 1980s and 1990s. "Ozone levels in Beijing today are similar to Los Angeles in the 1990s, when emission controls were just beginning to have an impact on reducing ozone levels there," said Cooper.For the past several years, wintertime haze pollution has been the main public concern in China and the focus of government action on air pollution, according to Zhang. The Chinese government has implemented stringent emission control measures to improve air quality: Since 2013, the Action Plan on Air Pollution Prevention and Control has reduced the concentration of primary air pollutants and particulate matter an average of 35 percent for 74 major cities.Zhang and Lu think the harmful effects of surface ozone pollution are much less recognized. "Many people in China do not realize that we may suffer severe ozone pollution under a typical blue sky in summer days. The emerging severity of ozone pollution in China now presents a new challenge for emission control strategies," Zhang said.Because ozone can harm plants, including crops, the researchers also investigated the potential for ozone-induced plant damage in China. One vegetation metric they examined captures accumulated ozone exposure exceeding a threshold above which tree growth or crop yield is expected to be reduced, over a crop's typical three-month growing season.In China, values for that metric were 1.4 -- 2 times higher than in Japan, South Korea, Europe, and the United States. Studies done before 2010 at a few Chinese sites concluded that ozone pollution was already reducing wheat yields up to 6-15 percent. "And because ozone levels in China have increased since then, we would expect to see even greater crop loss now," said Cooper.The database the researchers used in this analysis is part of the Tropospheric Ozone Assessment Report (TOAR), a series of global assessments of ozone pollution and its relevance to people, plants, and climate. CIRES' Owen Cooper is chair of the research project's steering committee. "This is exactly the kind of follow-on assessment we hoped TOAR would inspire," he said.According to lead author Zhang, scientists have known that there are high surface ozone levels in present-day China; what they didn't know was how China's ozone pollution compared with other industrialized countries in terms of magnitude, frequency, human, and vegetation exposure. "Our study presents such a novel comparison by combining the Chinese ozone data with the TOAR dataset," said Zhang.

Ozone Holes

August 14, 2018

https://www.sciencedaily.com/releases/2018/08/180814134159.htm

Natural refrigerant replacements could reduce energy costs and conserve the environment

The 1987 Montreal Protocol and the 1997 Kyoto Protocol called for countries around the world to phase out substances like CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), and HFCs (hydrofluorocarbons) that deplete the ozone layer and cause global warming. Many heating, ventilation and air conditioning systems still use these synthetic refrigerants that violate those international agreements and inflict environmental damage.

Recently, a team of Iranian researchers investigated how natural refrigerants could replace CFCs, HCFCs and HFCs in geothermal heat pumps to reduce energy consumption and operating costs. They report their findings in the The researchers also examined the environmental and economic benefits of zeotropic and azeotropic refrigerants, as well as natural refrigerants. Based on their modeling, the researchers determined that natural materials, including ammonia and n-butane, are the most economical and environmentally friendly replacement refrigerants for geothermal heat pumps.Geothermal heat pumps exploit how the earth's temperature below the surface stabilizes in mid-50s-degree Fahrenheit by using a vapor compression cycle equipped with buried pipes in horizontal trenches or vertical boreholes. Geothermal heat pumps extract heat from the ground (in the winter) and dissipate heat to the ground (in the summer) by circulating fluid such as water through buried pipes. This design takes advantage of the moderate temperatures in the ground to boost efficiency and reduce the operational costs of heating and cooling systems.In their review, the researchers ran an Hour Analysis Program to calculate the heating and cooling loads in a 14-story, residential building. Then, they applied their findings to an Engineering Equation Solver to model the thermodynamic cycle of an open and closed loop ground source heat pump with different known refrigerants."The big challenge for the coming years in the HVAC and refrigeration industry is to establish natural refrigerant technology to substitute CFCs, HCFCs and HFCs refrigerants," said Mostafa Mafi, one of the authors on the paper. "A solution to reduce energy consumption in heat pumps is using the earth as a renewable heat source/sink to both increase efficiency and create a diversity of energy sources."

Ozone Holes

August 7, 2018

https://www.sciencedaily.com/releases/2018/08/180807103659.htm

Iron-silica particles unlock part of the mystery of Earth's oxygenation

The oxygenation of Earth's atmosphere was thanks, in part, to iron and silica particles in ancient seawater, according to a new study by geomicrobiologists at the University of Alberta. But these results solve only part of this ancient mystery.

Early organisms called cyanobacteria produced oxygen through oxygenic photosynthesis, resulting in the oxygenation of Earth's atmosphere. But cyanobacteria needed protection from the sun's UV radiation in order to evolve. That's where iron and silica particles in ancient seawater come in, according to Aleksandra Mloszewska, a former PhD student who conducted this research under the supervision of Kurt Konhauser, professor in the Department of Earth and Atmospheric Sciences, and George Owttrim, professor in the Department of Biological Sciences.The research team characterized the effect of UV stress on cyanobacteria and the degree of radiation through the seawater medium through a combination of microbiological, spectroscopic, geochemical and modelling techniques. Their results show that the presence of high silica and iron concentrations in early sea water allowed for the formation of iron-silica precipitates that remained suspended in the ocean for extended periods of time."In effect, the iron-silica particles acted as an ancient 'sunscreen' for the cyanobacteria, protecting them from the lethal effects of direct UV exposure," said Konhauser, the senior author from UAlberta. "This was critical on the early Earth before a sufficiently thick ozone layer was established that could enable marine plankton to spread across the globe, as is the case today."But, the researchers explain, the iron-silica rich precipitates tell only part of the story."The accumulation of atmospheric oxygen from cyanobacterial facilitated the evolution of oxygen-based respiration and multicellular organisms," says Owttrim. But the reason for the large amount of time that it took for free oxygen to accumulate permanently in the atmosphere after the initial evolution of cyanobacteria remains a mystery.While iron-silica precipitates would have allowed early cyanobacteria to survive, UV radiation would still have prevented their widespread growth."It is likely that early cyanobacteria would not have been as productive as they are today because of the effects of UV stress. Until the accumulation of sufficient cyanobacteria-derived oxygen allowed a more permanent means of protection to develop, such as an ozone layer, UV stress may have played an even more important role in shaping the structure of the earliest ecosystems," explained Mloszewska.These new findings are helping researchers to understand not only how early cyanobacteria were affected by the high level of radiation on the early Earth but also the environmental dynamics that affected the oxygenation history of our atmosphere."These findings could also be used as a case study to help us understand the potential for the emergence of life on other planets that are affected by elevated UV radiation levels, for example Earth-sized rocky planets within the habitable zones of nearby M-dwarf star systems like TRAPPIST-1, Proxima Centauri, LHS 1140 and Ross 128 among others," said Mloszewska.The research was conducted in collaboration with colleagues at the University of Tuebingen and Yale University and was supported by the National Science and Research Council of Canada, and by the NASA Alternative Earths Astrobiology Institute. The paper, "UV radiation limited the expansion of cyanobacteria in early marine photic environments" is published in

Ozone Holes

July 18, 2018

https://www.sciencedaily.com/releases/2018/07/180718143112.htm

Ozone pollution in US national parks close to that of largest US cities

More than 300 million visitors travel to U.S. national parks every year to experience America's iconic landscapes. But poor air quality in parks may negatively affect visitation, according to a study published in

The researchers studied ozone levels in 33 of the largest national parks in the U.S. The researchers found that from 1990 to 2014 average ozone concentrations in national parks were statistically indistinguishable from those of the 20 largest U.S. metropolitan areas -- conditions that previously sparked federal legislation. To protect parks, the Clean Air Act (CAA) Amendments of 1977 and 1990 designated national parks as Federal Class I Areas."The U.S. has spent billions of dollars over the last three decades to improve air quality," said David Keiser, assistant professor of economics at Iowa State. "Given the popularity of national parks, as well as the fact that people go to parks to be outside, we believed it was worth better understanding air quality trends in these areas and whether people, through their actions, respond to changes in air quality in parks."The study found that ozone levels improved in metropolitan areas starting in 1990; however, national parks improvements have only been apparent since the early 2000s, corresponding to the passage of the Regional Haze Rule, a 1999 EPA regulation that strengthened air quality protections for national parks and wilderness areas.The authors first compiled data from extensive ozone monitoring efforts led by the National Park Service and the EPA. Data show that since 1990, national parks have seen only modest reductions in days with ozone concentrations exceeding 70 parts per billion, levels deemed unhealthy by the EPA.The researchers then matched the pollution data to monthly park visitation statistics at 33 of the most heavily visited national parks and found that visitation responds most to ozone during months with poor air quality. Unsurprisingly, this response is largest in summer and fall, the seasons when park visitation is highest. They also explored two potential causes for this result: air quality warnings (AQI) issued by parks and poor visibility. They found that the visitation response is more strongly associated with potential health warnings and less correlated with visibility.A recent survey found that nearly 90% of respondents had visited a national park area in their lifetime, with one-third of respondents anticipating visiting a park in the coming year. In spite of improvements over the last two decades, air quality in many national parks remains unhealthy for sensitive groups on average for two-and-one-half to three weeks per year.Indeed, despite the decrease in visitation found by the authors during months with poor air quality, an estimated 35 percent of all visitor days occurred when ozone exceeded the 55 ppb "Moderate" AQI threshold, and nearly 9 percent of visitor days when ozone levels exceeded 70 ppb. Exposure to these elevated ozone levels has important health implications -- visitors have an increased chance of adverse health outcomes, including hospitalization, respiratory symptoms, and mortality for sensitive individuals.The number of park visits suggests potentially large human health benefits to further air quality improvements at national parks and elsewhere.For 60 years, the Center for Agricultural and Rural Development (CARD) at Iowa State University has conducted innovative public policy and economic research on agricultural, environmental, and food issues. CARD combines academic excellence with engagement and anticipatory thinking to inform and benefit society. Center researchers develop and apply economic theory, quantitative methods and interdisciplinary approaches to create relevant knowledge. Communication efforts target state and federal policymakers, the research community, agricultural, food and environmental groups, individual decision-makers and international audiences.

Ozone Holes

July 10, 2018

https://www.sciencedaily.com/releases/2018/07/180710110137.htm

Pulse of the polar vortex revealed: A key to mapping future storms

If you can predict the path of the jet stream, the upper atmosphere's undulating river of wind, then you can predict weather -- not just for a week or two, but for an entire season. A new Stanford study moves toward that level of foresight by revealing a physical link between the speed and location of the jet stream and the strength of the polar vortex, a swirl of air that usually hovers over the Arctic.

"The jet stream sets everything," said Aditi Sheshadri, lead author and assistant professor of Earth System Science in the School of Earth, Energy, & Environmental Sciences (Stanford Earth). "Storms ride along it. They interact with it. If the jet stream shifts, the place where the storms are strongest will also shift."The research, published in the In one mode, changes in wind speed and direction start close to the equator in the troposphere, the wet, stormy layer of atmosphere below the jet stream and closest to Earth's surface. Shifts of wind in this mode quickly propagate up through the jet stream and into the polar vortex in the dry, upper layer of atmosphere known as the stratosphere.In the other mode, the strength of the stratosphere's polar vortex influences the path and strength of the jet stream -- and how it interacts with storms in the troposphere. In this mode, the polar vortex sends a signal all the way down to the surface like a pulse. A weaker vortex produces a weak jet stream that slips toward the equator; a stronger vortex intensifies the jet stream while drawing it poleward."These deep vertical structures haven't been shown before," Sheshadri said. "It's something fundamental about the system itself." Her analysis could help explain the surface weather impacts of an event that occurred in early 2018, when the vortex weakened so much that it ripped in two -- a phenomenon that scientists know can blast up to two months of extreme weather into western Europe. Until now, understanding of these interactions has been based on observations and statistical modeling rather than knowledge of their physical foundation.These modes could be key to predicting the long-term effects of certain environmental changes on Earth's surface. While air is thought to flow relatively independently within the troposphere and stratosphere in normal winters, depleted ozone, high levels of greenhouse gases, ocean warming, reduced snow cover, and other disturbances can rattle this independence, affecting both the vortex and jet stream in complex ways. Greenhouse gas emissions, for example, can strengthen the vortex while simultaneously boosting waves that propagate up from the troposphere and weaken the vortex as they break."We don't know which of these two effects of increasing greenhouse gases will win out," Sheshadri said.To help find answers, Sheshadri's team set out to understand the climate as a system that responds in a predictable way to known forces, despite internal dynamics that are a mix of random and systematic fluctuations. They took a mathematical theorem used for nearly a century to predict seemingly random behavior in quantum mechanical systems and applied it to data representing Earth's atmosphere in wintertime."We have 35 years of wind data," Sheshadri said. "Can we say something just from those observations about how the winds will change if, for instance, you increase carbon dioxide? That's what got this whole thing started."Current climate models excel at showing temperature changes throughout the atmosphere's layers over time and with varying levels of substances like ozone or carbon dioxide. "We're pretty certain about how the temperature structure of the atmosphere is going to change," Sheshadri said. "However, if you look at changes in things like wind or rain or snow -- anything that's a dynamical quantity -- we really have very little idea of what's going on."And yet, these are some of the most vivid metrics for a changing climate. "No one feels the global mean temperature," Sheshadri said. "How many times over the next 10 years are we going to have to deal with floods or cold snaps in a particular region? That's the sort of question this might help answer."By revealing the physical processes that underpin some of these dynamic variables, the method developed in this study could also help weed out flaws in climate models."The way that we currently do this is that you take a model and you run it forward," checking the model's predictions against observed data, Sheshadri explained. But many models built upon the same historic data produce different predictions for the future, in part because they make different assumptions about how the troposphere and stratosphere interact and how the jet stream fluctuates. Until now there has not been a way to check those assumptions against the atmosphere's actual variability."We need to be sure the models are right, and for the right reasons," Sheshadri said. The new work provides a way to resolve that uncertainty -- and to anticipate storms months into the future.

Ozone Holes

May 21, 2018

https://www.sciencedaily.com/releases/2018/05/180521131837.htm

Mediterranean diet may blunt air pollution's ill health effects

Eating a Mediterranean diet may protect people from some of the harm of long-term exposure to air pollution, and reduce their risk of dying from heart attacks, stroke and other causes of death, according to new research presented at the ATS 2018 International Conference.

"Previous studies have shown that dietary changes, particularly the addition of antioxidants, can blunt the adverse effects of exposure to high levels of air pollution over short time periods," said Chris C. Lim, MS, a doctoral student at the NYU School of Medicine. "What we did not know was whether diet can influence the association between long-term air pollution exposure and health effects."Rich in antioxidants, the Mediterranean diet favors fruits, vegetables, whole grains, legumes, olive oils, fish and poultry over red meat and processed foods. Antioxidants are molecules that disarm oxidized and highly reactive molecules, or free radicals, that are known to cause cell and tissue damage.The researchers analyzed data from the National Institutes of Health (NIH)-American Association of Retired Persons (AARP) Diet and Health Study. Over 17 years, the study followed 548,699 people (average age 62 at enrollment) from 6 states -- California, North Carolina, New Jersey, Florida, Louisiana and Pennsylvania -- and two cities -- Atlanta and Detroit. During that time, 126,835 people in the study group died.The researchers created five groups of participants based on their level of adherence to a Mediterranean diet and linked participants to estimates of long-term exposure to fine particulate matter (PM2.5), nitrogen dioxide (NOWhen comparing those least and most adherent to a Mediterranean diet, the study found that:Adherence to a Mediterranean diet did not appear, however, to protect against the harmful effects of long-term exposure to O"Given the benefits we found of a diet high in anti-oxidants, our results are consistent with the hypothesis that particle air pollution caused by fossil fuel combustion adversely affects health by inducing oxidative stress and inflammation," said senior study author George Thurston, ScD, director of the Program in Exposure Assessment and Human Health Effects at the Department of Environmental Medicine, NYU School of Medicine. "On the other hand, the ozone effect was not significantly blunted by a Mediterranean diet, so ozone apparently affects cardiac health through a different mechanism."With about one-fourth of the study population living where air pollution levels were 10 ?g/m3 or more above the lowest exposure, he added, "adoption of a Mediterranean diet has the potential to reduce the effects of air pollution in a substantial population in the United States."Study limitations include only having dietary information from the point when participants enrolled in the study and enrolling a higher percentage of white and well-educated Americans than are represented in the U.S. population as a whole.

Ozone Holes

May 16, 2018

https://www.sciencedaily.com/releases/2018/05/180516162520.htm

Rising emissions of ozone-destroying chemical banned by Montreal Protocol

Emissions of one of the chemicals most responsible for the Antarctic ozone hole are on the rise, despite an international treaty that required an end to its production in 2010, a new NOAA study shows.

Trichlorofluoromethane, or CFC-11, is the second-most abundant ozone-depleting gas in the atmosphere and a member of the family of chemicals most responsible for the giant hole in the ozone layer that forms over Antarctica each September. Once widely used as a foaming agent, production of CFC-11 was phased out by the Montreal Protocol in 2010.The new study, published today in "We're raising a flag to the global community to say, 'This is what's going on, and it is taking us away from timely recovery from ozone depletion,'" said NOAA scientist Stephen Montzka, lead author of the paper, which has co-authors from CIRES, the UK, and the Netherlands. "Further work is needed to figure out exactly why emissions of CFC-11 are increasing and if something can be done about it soon."CFCs were once widely used in the manufacture of aerosol sprays, as blowing agents for foams and packing materials, as solvents, and as refrigerants. Though production of CFCs was phased out by the Montreal Protocol, a large reservoir of CFC-11 exists today primarily contained in foam insulation in buildings, and appliances manufactured before the mid-1990s. A smaller amount of CFC-11 also exists today in chillers.Because CFC-11 still accounts for one-quarter of all chlorine present in today's stratosphere, expectations for the ozone hole to heal by mid-century depend on an accelerating decline of CFC-11 in the atmosphere as its emissions diminish -- which should happen with no new CFC-11 production.Despite the increase in CFC-11 emissions, its concentration in the atmosphere continues to decrease, but only about half as fast as the decline observed a few years ago, and at a substantially slower rate than expected. This means that the total concentration of ozone-depleting chemicals, overall, is still decreasing in the atmosphere. However, that decrease is significantly slower than it would be without the new CFC emissions.Precise measurements of global atmospheric concentrations of CFC-11 made by NOAA and CIRES scientists at 12 remote sites around the globe show that CFC-11 concentrations declined at an accelerating rate prior to 2002 as expected. Then, surprisingly, the rate of decline hardly changed over the decade that followed. Even more unexpected was that the rate of decline slowed by 50 percent after 2012. After considering a number of possible causes, Montzka and his colleagues concluded that CFC emissions must have increased after 2012. This conclusion was confirmed by other changes recorded in NOAA's measurements during the same period, such as a widening difference between CFC-11 concentrations in the northern and southern hemispheres -- evidence that the new source was somewhere north of the equator.Measurements from Hawaii indicate the sources of the increasing emissions are likely in eastern Asia. More work will be needed to narrow down the locations of these new emissions, Montzka said.The Montreal Protocol has been effective in reducing ozone-depleting gases in the atmosphere because all countries in the world agreed to legally binding controls on the production of most human-produced gases known to destroy ozone. Under the treaty's requirements, nations have reported less than 500 tons of new CFC-11 production per year since 2010. CFC-11 concentrations have declined by 15 percent from peak levels measured in 1993 as a result.That has led scientists to predict that by mid- to late-century, the abundance of ozone-depleting gases would to fall to levels last seen before the Antarctic ozone hole began to appear in the early 1980s.However, results from the new analysis of NOAA atmospheric measurements show that from 2014 to 2016, emissions of CFC-11 increased by more than 14,000 tons per year to about 65,000 tons per year, or 25 percent above average emissions during 2002 to 2012.To put that in perspective, production of CFC-11, marketed under the trade name Freon, peaked at about 430,000 tons per year in the 1980s. Emissions of this CFC to the atmosphere reached about 386,000 tons per year at their peak later in the decade.These findings represent the first time emissions of one of the three most abundant, long-lived CFCs have increased for a sustained period since production controls took effect in the late 1980s.If the source of these emissions can be identified and mitigated soon, the damage to the ozone layer should be minor. If not remedied soon, however, substantial delays in ozone layer recovery could be expected, Montzka said.David Fahey, director of NOAA"s Chemical Science Division and co-chair of the United Nations Environment Programme's Ozone Secretariat 's Science Advisory Panel, said ongoing monitoring of the atmosphere will be key to ensuring that the goal of restoring the ozone layer is achieved."The analysis of these extremely precise and accurate atmospheric measurements is an excellent example of the vigilance needed to ensure continued compliance with provisions of the Montreal Protocol and protection of the Earth's ozone layer," Fahey said.

Ozone Holes

November 13, 2017

https://www.sciencedaily.com/releases/2017/11/171113195010.htm

Air quality and health in U.S. will improve from other nations' actions to slow climate change

The United States will benefit from improved air quality in the future, through actions to reduce greenhouse gas (GHG) emissions both domestically and globally.

That is the primary finding of new research led by the University of North Carolina at Chapel Hill (UNC), published in the journal The study examined the benefits of global and domestic GHG mitigation on US air quality and human health in 2050, comparing a scenario with no global action to reduce GHGs with an aggressive scenario that significantly slows climate change. The GHG reduction scenario emphasizes energy efficiency and shifts energy production and use away from highly polluting forms toward cleaner sources with less air pollution.The study then quantified the health benefits of global GHG reductions, and for the first time separated those into contributions from foreign vs. domestic GHG mitigation. It showed that the health benefits to the US of reducing GHG emissions are significant, and in monetary terms would exceed the costs of reducing GHGs.Exposure to fine particulate matter (PMLead author Dr Jason West, from UNC, said: "PM"To explore the long-term effects of a global GHG mitigation strategy, we used dynamical downscaling from global simulations to predict the changes in air quality and related premature deaths."Co-lead author Dr Yuqiang Zhang said: "We found that the global GHG mitigation scenario reduces air pollution-related deaths in the US by 16,000 deaths in 2050 for PMThe team's results show that foreign GHG mitigation -- i.e. other countries implementing policies to reduce greenhouse gas emissions (such as the 2015 Paris Agreement) -- contributed 15 per cent of the total PM"Previous studies that estimated the health benefits of GHG reductions typically focused locally or nationally, and therefore missed the benefits from foreign reductions."Dr West added: "In monetary terms, we found that the benefits for avoided deaths from ozone and PM

Ozone Holes

November 6, 2017

https://www.sciencedaily.com/releases/2017/11/171106121306.htm

NASA satellite tracks ozone pollution by monitoring its key ingredients

Ozone pollution near Earth's surface is one of the main ingredients of summertime smog. It is also not directly measurable from space due to the abundance of ozone higher in the atmosphere, which obscures measurements of surface ozone. New NASA-funded research has devised a way to use satellite measurements of the precursor gases that contribute to ozone formation to differentiate among three different sets of conditions that lead to its production. These observations may also assist air quality managers in assessing the most effective approaches to emission reduction programs that will improve air quality.

Unlike its presence at high altitude where ozone acts as Earth's sunscreen from harmful ultraviolet radiation, at low altitudes, ozone is a health hazard contributing to respiratory problems like asthma and bronchitis. It is formed through complex chemical reactions initiated by sunlight and involving two types of gases, volatile organic compounds (VOC) and nitrogen oxides (NOx). Both are represented in the study by a major gas of each type, the VOC formaldehyde and NO2, that are measureable from space by the Dutch-Finnish Ozone Monitoring Instrument aboard NASA's Aura satellite, launched in 2004."We're using satellite data to analyze the chemistry of ozone from space," said lead author Xiaomeng Jin at the Lamont-Doherty Earth Observatory at Columbia University in Palisades, New York. Their research was published in With a combination of computer models and space-based observations, she and her colleagues used the concentrations of ozone's precursor molecules to infer whether ozone production increases more in the presence of NOx, VOCs, or a mix of the two, for a given location. Their study regions focused on North America, Europe and East Asia during the summer months, when abundant sunlight triggers the highest rates of ozone formation. To understand their impact on ozone formation, Jin and her team investigated whether VOC or NOx was the ingredient that most limited ozone formation. If emissions of that molecule are reduced, then ozone formation will be reduced -- critical information for air quality managers."We are asking, 'If I could reduce either VOCs or NOx, which one is going to get me the biggest bang for my buck in terms of the amount of ozone that we can prevent from being formed in the lower atmosphere?'" said co-author and atmospheric chemist Arlene Fiore at Lamont-Doherty, who is also a member of NASA's Health and Air Quality Applied Sciences Team that partially funded this work and fosters collaboration between scientists and air quality managers.The findings show that cities in North America, Europe and East Asia, are more often VOC-limited or in a transitional state between VOC and NOx-limited. In addition, the 12-year data record of satellite observations show that a location's circumstances can change. For instance, in 2005 New York City's ozone production during the warm season was limited by VOCs, but by 2015 it had transitioned to a NOx-limited system due to reduced NOx emissions resulting from controls put into place at both regional and national levels. This transition means that future NOx reductions will likely further decrease ozone production, said Jin.Volatile organic compounds occur in high volume naturally, given off by some plants, including certain tree species. They can also arise from paint fumes, cleaning products, and pesticides, and are a by-product of burning fossil fuels in factories and automobiles. Nitrogen oxides are a byproduct of burning fossil fuels and are abundant in cities, produced by power plants, factories, and cars. Because VOCs have a large natural source during summer over the eastern United States, for example, emission reduction plans over the last two decades in this region have focused on NOx, which is overwhelmingly produced by human activities.Space-based methods for monitoring ozone chemistry complement surface-based measurements made by air quality management agencies. The view from space offers consistent coverage of broad areas, and provides data for regions that may not have ground stations.

Ozone Holes

November 2, 2017

https://www.sciencedaily.com/releases/2017/11/171102121016.htm

Warm air helped make 2017 ozone hole smallest since 1988

Measurements from satellites this year showed the hole in Earth's ozone layer that forms over Antarctica each September was the smallest observed since 1988, scientists from NASA and NOAA announced today.

According to NASA, the ozone hole reached its peak extent on Sept. 11, covering an area about two and a half times the size of the United States -- 7.6 million square miles in extent -- and then declined through the remainder of September and into October. NOAA ground- and balloon-based measurements also showed the least amount of ozone depletion above the continent during the peak of the ozone depletion cycle since 1988. NOAA and NASA collaborate to monitor the growth and recovery of the ozone hole every year."The Antarctic ozone hole was exceptionally weak this year," said Paul A. Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "This is what we would expect to see given the weather conditions in the Antarctic stratosphere."The smaller ozone hole in 2017 was strongly influenced by an unstable and warmer Antarctic vortex -- the stratospheric low pressure system that rotates clockwise in the atmosphere above Antarctica. This helped minimize polar stratospheric cloud formation in the lower stratosphere. The formation and persistence of these clouds are important first steps leading to the chlorine- and bromine-catalyzed reactions that destroy ozone, scientists said. These Antarctic conditions resemble those found in the Arctic, where ozone depletion is much less severe.n 2016, warmer stratospheric temperatures also constrained the growth of the ozone hole. Last year, the ozone hole reached a maximum 8.9 million square miles, 2 million square miles less than in 2015. The average area of these daily ozone hole maximums observed since 1991 has been roughly 10 million square miles.Although warmer-than-average stratospheric weather conditions have reduced ozone depletion during the past two years, the current ozone hole area is still large because levels of ozone-depleting substances like chlorine and bromine remain high enough to produce significant ozone loss.Scientists said the smaller ozone hole extent in 2016 and 2017 is due to natural variability and not a signal of rapid healing.First detected in 1985, the Antarctic ozone hole forms during the Southern Hemisphere's late winter as the returning sun's rays catalyze reactions involving human-made, chemically active forms of chlorine and bromine. These reactions destroy ozone molecules.Thirty years ago, the international community signed the Montreal Protocol on Substances that Deplete the Ozone Layer and began regulating ozone-depleting compounds. The ozone hole over Antarctica is expected to gradually become less severe as chlorofluorocarbons -- chlorine-containing synthetic compounds once frequently used as refrigerants -- continue to decline. Scientists expect the Antarctic ozone hole to recover back to 1980 levels around 2070.Ozone is a molecule composed of three oxygen atoms that occurs naturally in small amounts. In the stratosphere, roughly 7 to 25 miles above Earth's surface, the ozone layer acts like sunscreen, shielding the planet from potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and also damage plants. Closer to the ground, ozone can also be created by photochemical reactions between the sun and pollution from vehicle emissions and other sources, forming harmful smog.Although warmer-than-average stratospheric weather conditions have reduced ozone depletion during the past two years, the current ozone hole area is still large compared to the 1980s, when the depletion of the ozone layer above Antarctica was first detected. This is because levels of ozone-depleting substances like chlorine and bromine remain high enough to produce significant ozone loss.NASA and NOAA monitor the ozone hole via three complementary instrumental methods. Satellites, like NASA's Aura satellite and NASA-NOAA Suomi National Polar-orbiting Partnership satellite measure ozone from space. The Aura satellite's Microwave Limb Sounder also measures certain chlorine-containing gases, providing estimates of total chlorine levels.NOAA scientists monitor the thickness of the ozone layer and its vertical distribution above the South Pole station by regularly releasing weather balloons carrying ozone-measuring "sondes" up to 21 miles in altitude, and with a ground-based instrument called a Dobson spectrophotometer.The Dobson spectrophotometer measures the total amount of ozone in a column extending from Earth's surface to the edge of space in Dobson Units, defined as the number of ozone molecules that would be required to create a layer of pure ozone 0.01 millimeters thick at a temperature of 32 degrees Fahrenheit at an atmospheric pressure equivalent to Earth's surface.This year, the ozone concentration reached a minimum over the South Pole of 136 Dobson Units on September 25 -- the highest minimum seen since 1988. During the 1960s, before the Antarctic ozone hole occurred, average ozone concentrations above the South Pole ranged from 250 to 350 Dobson units. Earth's ozone layer averages 300 to 500 Dobson units, which is equivalent to about 3 millimeters, or about the same as two pennies stacked one on top of the other."In the past, we've always seen ozone at some stratospheric altitudes go to zero by the end of September," said Bryan Johnson, NOAA atmospheric chemist. "This year our balloon measurements showed the ozone loss rate stalled by the middle of September and ozone levels never reached zero."

Ozone Holes

October 12, 2017

https://www.sciencedaily.com/releases/2017/10/171012091009.htm

New threat to the ozone layer

"Ozone depletion is a well-known phenomenon and, thanks to the success of the Montreal Protocol, is widely perceived as a problem solved," says University of East Anglia's David Oram. But an international team of researchers, led by Oram, has now found an unexpected, growing danger to the ozone layer from substances not regulated by the treaty. The study is published today in

Thirty years ago, the Montreal Protocol was agreed to phase-out chemicals destroying the ozone layer, the UV-radiation shield in the Earth's stratosphere. The treaty has helped the layer begin the slow process of healing, lessening the impact to human health from increased exposure to damaging solar radiation. But increasing emissions of ozone-destroying substances that are not regulated by the Montreal Protocol are threatening to affect the recovery of the layer, according to the new research.The substances in question were not considered damaging before as they were "generally thought to be too short-lived to reach the stratosphere in large quantities," explains Oram, a research fellow of the UK's National Centre for Atmospheric Science. The new Atmospheric Chemistry and Physics study raises the alarm over fast-increasing emissions of some of these very short-lived chemicals in East Asia, and shows how they can be carried up into the stratosphere and deplete the ozone layer.Emissions of ozone-depleting chemicals in places like China are especially damaging because of cold-air surges in East Asia that can quickly carry industrial pollution into the tropics. "It is here that air is most likely to be uplifted into the stratosphere," says co-author Matt Ashfold, a researcher at the University of Nottingham Malaysia Campus. This means the chemicals can reach the ozone layer before they are degraded and while they can still cause damage.One of the new threats is dichloromethane, a substance with uses varying from paint stripping to agricultural fumigation and the production of pharmaceuticals. The amount of this substance in the atmosphere decreased in the 1990s and early 2000s, but over the past decade dichloromethane became approximately 60% more abundant. "This was a major surprise to the scientific community and we were keen to discover the cause of this sudden increase," says Oram."We expected that the new emissions could be coming from the developing world, where industrialisation has been increasing rapidly," he says. The team set out to measure air pollution in East Asia to figure out where the increase in dichloromethane was coming from and if it could affect the ozone layer."Our estimates suggest that China may be responsible for around 50-60% of current global emissions [of dichloromethane], with other Asian countries, including India, likely to be significant emitters as well," says Oram.The scientists collected air samples on the ground in Malaysia and Taiwan, in the region of the South China Sea, between 2012 and 2014, and shipped them back to the UK for analysis. They routinely monitor around 50 ozone-depleting chemicals in the atmosphere, some of which are now in decline as a direct consequence of the Montreal Protocol.Dichloromethane was found in large amounts, and so was 1,2-dichloroethane, an ozone-depleting substance used to make PVC. China is the largest producer of PVC, which is used in many construction materials, and its production in the country has increased rapidly in the past couple of decades. But the rise in dichloroethane emissions was unexpected and surprising because the chemical is both a "valuable commodity" and "highly toxic," says Oram. "One would expect that care would be taken not to release [dichloroethane] into the atmosphere."Data collected from a passenger aircraft that flew over Southeast Asia between December 2012 and January 2014 showed that the substances weren't only present at ground level. "We found that elevated concentrations of these same chemicals were present at altitudes of 12 km over tropical regions, many thousands of kilometres away from their likely source, and in a region where air is known to be transferred into the stratosphere," says Oram.If the chemicals that were now discovered in unexpectedly large amounts can reach the ozone layer in significant quantities, they can cause damage. "We are highlighting a gap in the Montreal Protocol that may need to be addressed in the future, particularly if atmospheric concentrations continue to rise," Oram concludes.

Ozone Holes

August 16, 2017

https://www.sciencedaily.com/releases/2017/08/170816122340.htm

How future volcanic eruptions will impact Earth's ozone layer

The next major volcanic eruption could kick-start chemical reactions that would seriously damage the planet's already besieged ozone layer.

The extent of damage to the ozone layer that results from a large, explosive eruption depends on complex atmospheric chemistry, including the levels of human-made emissions in the atmosphere. Using sophisticated chemical modeling, researchers from Harvard University and the University of Maryland explored what would happen to the ozone layer in response to large-scale volcanic eruptions over the remainder of this century and in several different greenhouse gas emission scenarios. The research was published recently in Earth's stratosphere is still recovering from the historic release of chlorofluorocarbons (CFCs) and other ozone-depleting chemicals. Even though CFCs were phased out by the Montreal Protocol 30 years ago, levels of chlorine-containing molecules in the atmosphere are still elevated. Explosive volcanic eruptions that inject large quantities of sulfur dioxide into the stratosphere facilitate the chemical conversion of chlorine into more reactive forms that destroy ozone.Researchers have long known that when concentrations of chlorine from human-produced CFCs are high, ozone depletion will result following a volcanic eruption. When levels of chlorine from CFCs are low, volcanic eruptions can actually increase the thickness of the ozone layer. But exactly when this transition happens -- from eruptions that deplete ozone to eruptions that increase ozone layer thickness -- has long been uncertain. Previous research has put the window of the transition anywhere between 2015 to 2040.The Harvard researchers found that volcanic eruptions could result in ozone depletion until 2070 or beyond, despite declining concentrations of human-made CFCs."Our model results show that the vulnerability of the ozone column to large volcanic eruptions will likely continue late in to the 21st century, significantly later than previous estimates," said David Wilmouth, who directed the research and is a project scientist at the Harvard John A. Paulson School of Engineering and Applied Sciences and the Department of Chemistry and Chemical Biology.So, why is this shift happening so much later than previously thought?"Previous estimates did not take into account certain natural sources of halogen gases, such as very-short lived bromocarbons originating from marine plankton and microalgae," said Eric Klobas, lead author and Harvard chemical physics PhD candidate.Accounting for these emissions fine-tunes the timing of the shift from eruptions that cause ozone depletion to eruptions that increase the thickness of the ozone layer. These natural sources of bromine become especially important in the lower stratosphere after concentrations of human-emitted CFCs have declined."We found that the concentration of bromine from natural, very short-lived organic compounds is critically important," said Klobas. "Even small, part-per-trillion changes in the amount of bromine from these sources can mean the difference between a late 21st century volcanic eruption resulting in ozone column depletion or ozone column enhancement."The researchers then explored how a volcanic event the size of the Mount Pinatubo eruption, which shot about 20 million metric tons of sulfur dioxide into the stratosphere in 1991, would impact the ozone layer in 2100. The team modeled four different greenhouse gas emission scenarios, ranging from very optimistic to what is commonly considered the worst-case scenario.The team found that the most optimistic projection of future greenhouse gas concentrations resulted in the most ozone depletion from a volcanic eruption. Conversely, in the pessimistic scenario in which greenhouse gas emissions continue to increase rapidly throughout the 21st century, a Mount Pinatubo-size eruption would actually lead to a slight increase in ozone. The researchers found that the colder stratospheric temperatures and higher methane levels in this scenario would curb important ozone-depleting chemical reactions.But, here's the kicker: all of the above scenarios assumed that the volcanic eruption would only inject sulfur into the stratosphere, like the 1991 eruption of Mount Pinatubo in the Philippines. If the eruption were to also inject halogen-containing chemicals such as hydrogen chloride (HCl) into the stratosphere, the results could be dire."If volcanic halogens, which are commonly present in large quantities in volcanic eruptions, were to partition substantially into the stratosphere -- in any greenhouse gas emission scenario, at any point in the future -- it would potentially cause severe losses of stratospheric ozone," said Klobas.In such a case, the United States could see a prolonged and significant decrease in ozone layer thickness -- upwards of 15 to 25 percent in the highest halogen scenario modeled. Even small reductions in the thickness of the ozone layer, which shields the surface of the Earth from DNA-destroying ultraviolet radiation, can adversely impact human health and other life on this planet."These eruptions are highly unusual events but the possibility does exist, as evidenced in the historical record," said Wilmouth.

Ozone Holes

August 14, 2017

https://www.sciencedaily.com/releases/2017/08/170814121047.htm

Ozone treaty taking a bite out of US greenhouse gas emissions

The Montreal Protocol, the international treaty adopted to restore Earth's protective ozone layer in 1989, has significantly reduced emissions of ozone-depleting chemicals from the United States. In a twist, a new study shows the 30-year old treaty has had a major side benefit of reducing climate-altering greenhouse gas emissions from the U.S.

That's because the ozone-depleting substances controlled by the treaty are also potent greenhouse gases, with heat-trapping abilities up to 10,000 times greater than carbon dioxide over 100 years.The new study is the first to quantify the impact of the Montreal Protocol on U.S. greenhouse gas emissions with atmospheric observations. The study's results show that reducing the use of ozone-depleting substances from 2008 to 2014 eliminated the equivalent of 170 million tons of carbon dioxide emissions each year. That's roughly the equivalent of 50 percent of the reductions achieved by the U.S. for carbon dioxide and other greenhouse gases over the same period. The study was published today in "We were surprised by the size of the decline, especially compared with other greenhouse gases," said Lei Hu, a researcher with the Cooperative Institute for Research in Environmental Sciences (CIRES) working at NOAA and lead author of the new study.Hu added that the benefits of the Montreal Protocol on greenhouse gas emissions would likely grow in the future. By 2025, she projects that the effect of the Montreal Protocol will be to reduce U.S. greenhouse gas emissions by the equivalent of 500 million tons of carbon dioxide per year compared with 2005 levels. This reduction would be equivalent to about 10 percent of the current U.S. emissions of carbon dioxide.Previous studies have demonstrated that the Montreal Protocol has been more effective at curtailing global greenhouse gas emissions than any other international effort -- even though climate change was not a consideration during the initial treaty negotiations in the late 1980s.The new analysis, based on data collected by NOAA's atmospheric monitoring network, confirms that the Montreal Protocol has been highly successful in the U.S. in its primary goal -- reducing emissions of manufactured chlorine-based chemicals that, in addition to depleting ozone world-wide, create a hole the size of the continental U.S. in the Earth's protective ozone layer over the Antarctic each September and October.Those chemicals -- chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), and their substitutes, the hydrofluorocarbons (HFCs) -- have been widely used as refrigerants, foam blowing agents, aerosol propellants, fire retardants, and solvents. Chlorine from CFCs was first identified as capable of destroying stratospheric ozone in 1974. The Montreal Protocol has controlled the production and consumption of these chemicals since the late 1980s.Implementation of the Montreal Protocol in the United States, largely through the Clean Air Act, led to a near complete phase-out of U.S. production and consumption of chlorofluorocarbons (CFCs) beginning in 1996 and a 95 percent decline of hydrochlorofluorocarbons (HCFCs) production since 1998.As a result, total emissions of CFCs in the U.S. have decreased by two-thirds from 2008 to 2014, while emissions of HCFCs declined by about half, the study authors said.Another indication of the treaty's impact is increasing U.S. emissions of ozone-friendly chemicals, such as hydrofluorocarbons or HFCs. However, some HFCs are also potent greenhouse gases, and their increased use is offsetting some of the climate benefit of the Montreal Protocol, said Stephen Montzka, a researcher at NOAA and co-author of the new study.Countries adhering to the Protocol, including the U.S., agreed to limit future production and consumption of HFCs in 2016."This shows what can be achieved by concerted and thoughtful international effort," said Scott Lehman of the Institute of Arctic and Alpine Research at the University of Colorado Boulder and co-author of the new study. "Hopefully, the Protocol can serve as a model of the international cooperation that we need to tackle the real problem -- carbon dioxide."

Ozone Holes

August 7, 2017

https://www.sciencedaily.com/releases/2017/08/170807151722.htm

Choice of cool roofing materials can potentially impact region's air pollution

In a groundbreaking study released today, scientists at the South Coast Air Quality Management District and the University of Southern California have found that widespread installation of certain "cool roof" materials in the region could slightly increase ozone and fine particulate pollution levels.

The study explains how the predicted increase in ozone levels can be minimized or possibly avoided by requiring more comprehensive performance standards for cool-roofing materials. However, small increases in fine particulate (PM2.5) levels are predicted to occur with or without enhanced standards."Cool roofs have many benefits including reduced energy use for cooling and mitigation of the significant health impacts of heat waves." said Wayne Nastri, SCAQMD's executive officer."While the future, widespread use of certain kinds of cool roofing materials could slightly increase air pollution levels, we in no way want to discourage this technology. This study shows what needs to be done to help cool our cities and avoid increasing ozone levels as an unintended consequence."The study, titled "Air Quality Implications of Widespread Adoption of Cool Roofs on Ozone and Particulate Matter in Southern California," was published in the The scientific paper was produced by a team of SCAQMD scientists led by Scott A. Epstein, Ph.D., in collaboration with George Ban-Weiss, Ph.D., a professor of civil and environmental engineering at USC. They used sophisticated meteorology and air quality computer models, measurements of cool roofing materials and detailed databases of the region's rooftops to predict the air quality impacts of the increasing use cool roof materials -- typically light-colored and highly reflective -- that are expected to result from current statewide energy efficiency standards.Numerous scientific studies have established that replacing darker roofs and building materials with highly reflective materials can reduce peak daytime temperatures and mitigate the so-called "urban heat island effect" where cities can be several degrees warmer than less-urbanized surrounding areas.However, many cool-roofing materials reflect more ultraviolet light (UV) than their traditional counterparts, increasing the potential for ozone formation. UV rays fuel smog formation on their way down to Earth. When cool roofs bounce UV rays back up into the atmosphere they create a "double-shot" of ozone formation.This ozone increase can be avoided if a comprehensive roofing standard is adopted to prevent the overall UV reflectance of newly-installed cool roofs from increasing. Cool roofing materials are available today that reflect the same amount or even less UV than traditional, roofing materials."This study highlights the importance of considering how strategies used to mitigate one environmental issue can have co-benefits and/or unintended consequences on other environmental systems," Ban-Weiss said. "Whether air pollution improves or worsens from cool roof installations depends on a host of competing chemical and meteorological factors."Given that our study focuses on the Los Angeles basin, future research is needed to investigate how these competing processes dictate air pollution impacts in cities around California and beyond."While an increase in ozone formation can be mitigated by changing cool roofing materials, the predicted small increase in PM2.5 levels is due to overall cooler surface temperatures resulting in weaker sea breezes and lower inversion layers, and will occur regardless of UV reflectance of roofing materials, according to the study.The study also noted the installation of cool paving materials could have an even bigger impact on ozone and PM2.5 levels since the amount of area paved in the region is significantly larger than the total roofing area affected by state energy efficiency standards.

Ozone Holes

July 31, 2017

https://www.sciencedaily.com/releases/2017/07/170731114536.htm

Climate change expected to increase premature deaths from air pollution

A new study from the University of North Carolina at Chapel Hill estimates that future climate change, if left unaddressed, is expected to cause roughly 60,000 deaths globally in the year 2030 and 260,000 deaths in 2100 due to climate change's effect on global air pollution.

The study, to appear in the July 31 advance online issue of "As climate change affects air pollutant concentrations, it can have a significant impact on health worldwide, adding to the millions of people who die from air pollution each year, " said Jason West, who led the research at UNC-Chapel Hill with former graduate student and first author Raquel Silva.Hotter temperatures speed up the chemical reactions that create air pollutants like ozone and fine particulate matter, which impact public health. Locations that get drier may also have worse air pollution because of less removal by rain, and increased fires and windblown dust. As trees respond to higher temperatures, they will also emit more organic pollutants.West and Silva used an ensemble of several global climate models to determine the number of premature deaths that would occur due to ozone and particulate matter in 2030 and 2100. For each model, the team assessed the projected changes in ground-level air pollution that could be attributed to future climate change. They then overlaid these changes spatially on the global population, accounting for both population growth and expected changes in susceptibility to air pollution.In aggregate, West and Silva found that climate change is expected to increase air pollution-related deaths globally and in all world regions except for Africa. Specifically, five out of eight models predicted there will be more premature deaths in 2030, and seven of nine models in 2100."Our finding that most models show a likely increase in deaths is the clearest signal yet that climate change will be detrimental to air quality and health," said West, associate professor of environmental sciences and engineering in the UNC Gillings School of Global Public Health. "We also collaborated with some of the world's top climate modeling groups in the United States, United Kingdom, France, Japan and New Zealand, making this study the most comprehensive yet on the issue."In addition to exacerbating air pollution-related deaths, climate change is expected to affect health through changes in heat stress, access to clean water and food, severe storms and the spread of infectious diseases.

Ozone Holes

July 23, 2017

https://www.sciencedaily.com/releases/2017/07/170723203228.htm

Campaigning on climate science consensus may backfire, warn scholars

Climate change campaigns that focus on correcting public beliefs about scientific consensus are likely to backfire and undermine policy efforts, according to an expert commentary published today in

The six authors of the commentary argue campaigns which emphasize variations on messages such as, "97% of climate scientists have concluded that human-caused climate change is happening," hold several serious drawbacks.Firstly, the difficulties involved in statistically quantifying consensus and what is included in the climate science literature have generated intense disagreement. The messaging strategy has also promoted confusion over whether consensus extends to various impacts such as extreme weather events. Rather than ending conflict over the reality of human-caused climate change, these efforts have fueled further debate.Secondly, the studies evaluating the impact of consensus messaging on public attitudes have been published by a relatively small group of affiliated researchers and challenged by other social scientists, resulting in an uncertain evidence-base around which to invest funding on behalf of expensive communication campaigns.Thirdly, past scholarship suggests that acceptance of scientific consensus is not needed for the public to support solutions to environmental problems. For example, the Montreal Protocol for the protection of the ozone layer was signed in the face of the shocking discovery of the ozone hole. However, a decade earlier the US public had already started to shift from using spray cans containing ozone destroying chemicals, at a time when no scientific consensus on ozone layer protection existed.The final point discussed highlights how narrowly focusing on scientific consensus displaces debate over the wider issues posed by climate change, which involve many different, and often conflicting, policy options.Co-author, Reiner Grundmann, from the School of Sociology and Social Policy at University of Nottingham in the UK, commented: "The '97% consensus' has become a popular slogan for climate campaigners, but the strategy is self-defeating. There is a danger of overreach in that numbers like the 97% consensus are implicitly extended to all areas of climate science, and used to close down debate over complex topics like extreme weather events. This approach also makes the implausible assumption that publics will follow the correct policy path once given the relevant scientific information, and that acceptance of scientific consensus is needed to support specific solutions."

Ozone Holes

July 17, 2017

https://www.sciencedaily.com/releases/2017/07/170717110507.htm

Ozone pollution connected to cardiovascular health

Exposure to ozone, long associated with impaired lung function, is also connected to health changes that can cause cardiovascular disease such as heart attack, high blood pressure and stroke, according to a new study of Chinese adults.

These findings, by a team from Duke University, Tsinghua University, Duke Kunshan University and Peking University, appear in the July 17, 2017 edition of Ozone is a pollutant formed through a chemical reaction that occurs when sunlight interacts with nitrogen oxides and other organic compounds that are generated by coal-burning, vehicle exhaust and some natural sources."We know that ozone can damage the respiratory system, reduce lung function and cause asthma attacks," said study author Junfeng (Jim) Zhang, from Duke and Duke Kunshan University. "Here, we wanted to learn whether ozone affects other aspects of human health, specifically the cardiovascular system."Zhang and colleagues studied 89 healthy adults living in Changsha City, China, for one year. They monitored indoor and outdoor ozone levels, along with other pollutants. At four intervals, the study team took participant blood and urine samples and used a breathing test called spirometry to examine a set of factors that could contribute to cardiovascular and respiratory disease.The team examined inflammation and oxidative stress, arterial stiffness, blood pressure, clotting factors and lung function in participants. They noted blood platelet activation (a risk factor for clotting) and an increase in blood pressure, suggesting a possible mechanism by which ozone may affect cardiovascular health. These effects were found with ozone exposure lower than that which affects respiratory health, and lower than current Environmental Protection Agency (EPA) air quality standards."This study shows that standards for safe ozone exposure should take into account its effect on cardiovascular disease risk," said Zhang."In 2015, 108 million Americans -- one third of the population -- lived in counties with ozone levels that exceeded standards set by the EPA," Zhang said. "In contrast, only 31 million Americans live in counties where other pollutants exceed EPA standards."The production of ozone globally will be exacerbated by a warmer climate, "so it will be an increasing trend with climate change," said Zhang. Ozone is a difficult pollutant to control because its creation in the atmosphere is complex. "For example, a reduction in nitrogen oxides does not necessarily mean a reduction in ozone levels," Zhang said.

Ozone Holes

June 28, 2017

https://www.sciencedaily.com/releases/2017/06/170628183211.htm

Study of US seniors strengthens link between air pollution and premature death

A new study of 60 million Americans -- about 97% of people age 65 and older in the United States -- shows that long-term exposure to airborne fine particulate matter (PM2.5) and ozone increases the risk of premature death, even when that exposure is at levels below the National Ambient Air Quality Standards (NAAQS) currently established by the U.S. Environmental Protection Agency.

The Harvard T.H. Chan School of Public Health researchers found that men, blacks, and low-income populations had higher risk estimates from PM2.5 exposure compared with the national average, with blacks having mortality risks three times higher than the national average.The results showed that if the level of PM2.5 could be lowered by just 1 microgram per cubic meter (ug/m3) nationwide, about 12,000 lives could be saved every year. Similarly, if the level of ozone could be lowered by just 1 part per billion (ppb) nationwide, about 1,900 lives would be saved each year.The study will be published in the June 29, 2017 issue of the "This is a study of unprecedented statistical power because of the massive size of the study population. These findings suggest that lowering the NAAQS for fine particulate matter will produce important public health benefits, especially among self-identified racial minorities and people with low incomes," said Francesca Dominici, principal investigator of this study and professor of biostatistics at Harvard Chan School and co-director of the Harvard Data Science Initiative.The researchers examined Medicare claims records of 60 million Americans 65+ over a seven-year period, representing 460 million person-years of follow-up. They also estimated air pollution levels at each 1 kilometer grid for the entire U.S. upon which the claims data could be overlaid and interpreted.To do this, the Harvard Chan researchers leveraged the results of an exposure prediction model developed by doctoral student Qian Di and Joel Schwartz, professor of environmental epidemiology and the study's senior author. The exposure prediction model leverages satellite-based measurements and a computer simulation of air pollution.By relying on this well-validated prediction model, the team was able to include subjects who live in unmonitored and less-populated areas so that the effects of air pollution on all 60 million people could be analyzed regardless of whether they lived in urban, suburban, or rural areas."This study shows that although we think air quality in the United States is good enough to protect our citizens, in fact we need to lower pollution levels even further," said Schwartz.

Ozone Holes