Short-term exposure to high levels of air pollution kills 1 million globally every year

Every year, more than one million deaths globally occur because of exposure to short-term (hours to days) fine particulate matter (PM2.5) in air pollution, according to a new report, with Eastern Asia reporting more than 50% of deaths attributable to short-term PM2.5 globally.

To date most studies have focused on the health impacts of living in cities where pollution levels are consistently high, ignoring the frequent "spikes" in pollution that can impact smaller urban areas that occur for instance landscape fires, dust, and other intermittent extreme air-pollution concentration events.

The Monash University study, looking at mortality and pollution levels of PM2.5 in over 13,000 cities and towns across the globe in the two decades to 2019, is published today in The Lancet Planetary Health.

Led by Professor Yuming Guo, the study is important because it is the first to look at short-term exposure globally -- rather than the long-term impacts of persistent exposure such as for people living in cities with high pollution levels.

The researchers found that breathing in PM2.5 for even a few hours, and up to a few days, results in more than one million premature deaths occurring worldwide every year, particularly in Asia and Africa, and more than a fifth (22.74%) of them occurred in urban areas.

According to Professor Guo, the short-term health effects of being exposed to air pollution have been well documented, "such as the megafires in Australia during the so-called Black Summer of 2019-20 which were estimated to have led to 429 smoke-related premature deaths and 3230 hospital admissions as a result of acute and persistent exposure to extremely high levels of bushfire-related air pollution," he said.

"But this is the first study to map the global impacts of these short bursts of air pollution exposure."

The authors add that because of the high population densities in urban areas together with high levels of air pollution, "understanding the mortality burden associated with short-term exposure toPM2.5 in such areas is crucial for mitigating the negative effects of air pollution on the urban population."

According to the study:

• Asia accounted for approximately 65.2% of global mortality due to short-term PM2.5 exposure
• Africa 17.0%
• Europe 12.1%
• The Americas 5.6%
• Oceania 0.1%

The mortality burden was highest in crowded, highly polluted areas in eastern Asia, southern Asia, and western Africa with the fraction of deaths attributable to short-term PM2.5 exposure in eastern Asia was more than 50% higher than the global average.

Most areas in Australia saw a small decrease in the number of attributable deaths, but the attributable death fraction increased from 0.54% in 2000 to 0.76% in 2019, which was larger than any other subregions.

One potential reason could be the increasing frequency and scale of extreme weather-related air pollution events, such as bushfire events in 2019.

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Air pollution hides increases in rainfall

We know that greenhouse gas emissions like carbon dioxide should increase rainfall. The emissions heat the atmosphere, causing a one-two punch: warmer oceans make it easier for water to evaporate, and warmer air can hold more water vapor, meaning more moisture is available to fall as rain. But for much of the 20th century, that increase in precipitation didn't clearly show up in the data.

A new study led by researchers at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) finds that the expected increase in rain has been largely offset by the drying effect of aerosols -- emissions like sulfur dioxide that are produced by burning fossil fuels, and commonly thought of as air pollution or smog.

The research is published today in the journal Nature Communications.

"This is the first time that we can really understand what's causing extreme rainfall to change within the continental U.S.," said Mark Risser, a research scientist at Berkeley Lab and one of the lead authors for the study.

He noted that until the 1970s, the expected increases to extreme rainfall were offset by aerosols.

But the Clean Air Act caused a drastic reduction in air pollution in the United States.

"The aerosol masking was turned off quite suddenly. That means rainfall might ramp up much more quickly than we would have otherwise predicted."

Traditional climate models have struggled to confidently predict the human impact on rainfall at scales smaller than a continent -- and that regional level is precisely where most climate change adaptations and mitigations take place.

By using a new method and relying heavily on measurements from rain gauges from 1900 to 2020, researchers were able to more robustly determine how human activities have influenced rainfall in the United States.

"Prior to our study, the Intergovernmental Panel on Climate Change [IPCC] had concluded that the evidence was mixed and inconclusive for changes in U.S. precipitation due to global warming," said Bill Collins, associate laboratory director for the Earth and Environmental Sciences Area at Berkeley Lab and co-lead author on the study.

"We have now provided conclusive evidence for higher rainfall and also helped explain why past studies assessed by the IPCC reached conflicting conclusions."

Specifically, the study isolates how greenhouse gas and aerosol emissions affect both average and extreme rainfall.

Researchers confirmed that increased greenhouse gas emissions, which quickly disperse over the whole planet, cause an increase in rainfall.

The impact from aerosols is more nuanced. Over the long term, aerosols cool the planet, which causes a drying effect.

But they also have a faster, more local response. That fast impact depends on the season, with aerosols generally reducing rainfall in the winter and spring, and amplifying it in summer and fall over much of the United States.

"The seasonality piece is really important," Risser said. "For rainfall, the nature of climate change depends on what season you're talking about, since different kinds of weather systems create precipitation in different parts of the year."

Some of the conflicting studies looking at precipitation trends of the last century can be explained by how the effect of aerosols offsets the effect of greenhouse gases, and how models and simulations factor in these two driving forces.

The researchers noted that tracking aerosols and incorporating them more fully into models and simulations will be important for improving the predictions used for infrastructure design and water resource management.

The United States has already seen examples of recent increases in extreme precipitation, with several intense, record-setting storms in the past few years.

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Death toll shows extreme air pollution events a growing urban threat

New Curtin University-led research has estimated that 1454 avoidable deaths (one person every five days) occurred in Australian capital cities in the past 20 years because of fine particle air pollution from extreme events such as bushfires and dust storms, wood-heater smoke or industrial accidents.

The study also found that nearly one-third of deaths from extreme air pollution exposure days could be prevented if pollution events were reduced by as little as 5 per cent.

Lead researcher Dr Lucas Hertzog from Curtin's World Health Organisation Collaborating Centre for Climate Change and Health Impact Assessment said the findings highlighted the urgent need for effective strategies to manage air quality, particularly during extreme weather events like bushfires and dust storms, which are becoming more common due to climate change.

"Using data from 2001 to 2020 from air pollution monitoring sites, combined with a range of satellite and land use-related data, we modelled the exposure to exceptional levels of particulate matter air pollution (PM2.5) for each extreme pollution exposure day," Dr Hertzog said.

"Despite relatively low daily PM2.5 levels generally (compared to global averages), Australian cities experience days with extreme pollution levels where PM2.5 concentrations exceed the WHO Air Quality Guideline standard.

"Sydney and Melbourne reported the highest number of deaths attributable to extreme air pollution events, with 541 and 438 deaths respectively, followed by Brisbane and Perth with 171 and 132 deaths."

"Adelaide and Hobart were the cities that showed, across the 20-year period, fewer days exceeding WHO air quality exposure recommendations, with Adelaide recording only five days and Hobart 11 days above the threshold.

"Darwin, despite its relatively low number of deaths due to PM2.5 exposure events, experienced a high number of days exceeding WHO recommendations, ten times more than cities like Melbourne."

Dr Hertzog said the findings show how extreme air pollution events could seriously affect health in urban areas, and understanding this link was crucial, as climate change may increase the frequency and intensity of such pollution events.

"Diseases associated with particulate matter air pollution include asthma and COPD (chronic obstructive pulmonary disease) as well as cardiovascular disorders," Dr Hertzog said.

"Our study's insights can aid in protecting public health by helping to inform policy development and actions to reduce impacts from extreme air pollution events.

"While responding to bushfires and dust storms is an increasingly challenging task, authorities have a crucial role in land use management. They also regulate energy policy and control wood heater regulations. Additional strategies to reduce emissions from industrial accidents or road transport-related smog events could enhance the control of sources of air pollution and improve well-being.

"It is also possible to reduce the burden of mortality by improving public health warnings and increasing community awareness of smoke avoidance behaviours."

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US air pollution rates on the decline but pockets of inequities remain

Over the last decades, air pollution emissions have decreased substantially; however, the magnitude of the change varies by demographics, according to a new study by Columbia University Mailman School of Public Health. The results indicate there are racial/ethnic and socioeconomic disparities in air pollution emissions reductions, particularly in the industry and energy generation sectors. The findings are published in the journal Nature Communications.

The research provides a national investigation of air pollution emission changes in the 40 years following the enactment of the Clean Air Act (CAA). Until now, studies have primarily focused on evaluating air pollution disparities at a single time point, focusing on pollutant concentrations instead of emissions. A focus on emissions, however, has more direct implications for regulations and policies. In this study, the researchers used county-level data to evaluate racial/ethnic and socioeconomic disparities in air pollution emissions changes in the contiguous U.S. from 1970 to 2010.

"The analyses provide insight on the socio-demographic characteristics of counties that have experienced disproportionate decreases in air pollution emissions over the last forty years," said Yanelli Nunez, PhD, the study's first author, who is a scientist in the Department of Environmental Health Sciences at Columbia Mailman School of Public Health and affiliated with PSE Healthy Energy. Additionally, by analyzing air pollution emissions, the researchers identified specific pollution source sectors that are potentially important contributors to air pollution exposure disparities.

Nunez and colleagues leveraged air pollution emissions data from the Global Burden of Disease Major Air Pollution Sources inventory to analyze air pollutant emissions from six pollution source sectors: industry (sulfur dioxide), energy (sulfur dioxide and nitrogen oxides), agriculture (ammonia), on-road transportation (nitrogen oxides), commercial (nitrogen oxides), and residential (particles of organic carbon).

On average, national U.S. air pollution emissions declined substantially from 1970 to 2010 from all source sectors the researchers considered except for ammonia emissions from agriculture and organic carbon particle emissions from the residential sector, which the researchers indicate is primarily from using solid biofuels for indoor heating. The most pronounced emission decreases were observed for sulfur dioxidefrom industrial and energy generation activities. Nitrogen oxide emissions from transportation, commercial activities, and energy generation decreased moderately.

Despite the overall downward trends for most pollutants, the researchers found that certain populations experienced relatively smaller reductions or even increases in air pollution emissions. For instance, an increase in a county's average Hispanic or Indian American population percentage resulted in a relative increase in sulfur dioxide, nitrogen oxides, and ammonia emissions from the industry, energy generation, and agriculture sectors, respectively. Additionally, an increase in the county median family income was linked with an increase in the magnitude of emissions reductions in every pollution source sector the researchers analyzed, except agriculture.

"Air pollution emissions do not perfectly capture population air pollution exposure, and we also know that neighborhood-level air pollution inequities are common, which we were not able to analyze in this study given the data at hand," noted Marianthi-Anna Kioumourtzoglou, ScD, associate professor of environmental health sciences at Columbia Mailman School, and senior author. "In this study, we provide information about potential racial/ethnic and socioeconomic inequalities in air pollution reductions nationwide from major air pollution sources, which can inform regulators and complement local-level analysis."

"Policies specifically targeting reductions in overburdened populations could support more just reductions in air pollution and reduce disparities in air pollution exposure," observed Dr. Nunez. "This is an important lesson gained from 53 years of Clean Air Act implementation, which is particularly relevant as we develop policies to transition to renewable energy sources, which will have a collateral impact on air quality and, as a result, on public health."

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Africa's dangerous air pollution levels are a global problem, says new research

A new report in Nature Geoscience has brought to light the challenge of air pollution levels in Africa and why international action is needed to combat it.

Over the last 50 years African nations have suffered from rapidly deteriorating air quality, making their cities some of the most polluted in the world. Particulate matter concentration levels are now five to ten levels greater than that recommended by the World Health Organisation, with the situation predicted to worsen as populations grow and industrialization accelerates.

However, far too little has been done to try and combat the dangerous air quality with just 0.01% of global air pollution funding currently spent in Africa.

The new perspective piece from the University of Birmingham, the University of Cambridge, Imperial College London, South Eastern Kenya University and the African Centre for Clean Air, published today (7 Nov) in Nature Geoscience, argues that tackling this issue requires collective efforts from African countries, regionally tailored solutions, and global collaboration.

Francis Pope, Professor of Atmospheric Science at the University of Birmingham and one of the co-authors, said: "The burning of biomass fuel for cooking, heating, and lighting, the crude oil exploitation and coal mining industries, and old vehicles being shipped in from Europe are all causes for the poor air quality in African nations. This dangerous air can cause complex and sometimes deadly health issues for those breathing it in. If this wasn't enough of a reason to tackle this issue, air pollution in Africa is not just a problem for people living on the continent, but for the wider world, limiting the ability to meet global climate targets and combat the climate emergency."

Multiple efforts have been made over the years to tackle air pollution, such as the signing of C40 Clean Air Declaration by ten major African cities. Initiatives to monitor air-pollution levels and collect much needed data have also begun to gather momentum.

But there is still much to be done. The researchers argue that regional and international efforts must be coordinated to achieve real change and leverage existing knowledge on controlling and cutting air pollution.

They call for urgent collaboration on:

• Continuous air monitoring via a network of sensors in order to build a detailed picture of air pollution variations and track progress.
• Investment in clean energy such as solar, hydropower and wind to meet Africa's energy demand which is expected to double by 2040.
• Improved solid waste management to prevent dumping and burning of waste and improve reuse, recycling, and recovery rates.
• Investment in environmentally friendly technology to ensure African countries can grow economically whilst avoiding dirty and obsolete technology from the Global North.
• Infrastructure improvements to curb emissions from the transport sector, improving public transport provision and adopting higher emission standards for fuel and imported vehicles.

Co-author of the article, Dr Gabriel Okello, from the Institute for Sustainability Leadership at the University of Cambridge and the African Centre for Clean Air, said: "Air pollution is complex and multifaceted with different sources and patterns within society. Addressing it requires more ambitious, collaborative, and participatory approaches centred on involvement of stakeholders in policy, academia, business, communities to co-design and co-produce context-specific interventions. This should be catalysed by increased investment in interventions that are addressing air pollution. Africa has the opportunity to leverage the growing political will and tap into the young population to accelerate action towards the five broad suggestions in our paper."

Dr Andriannah Mbandi, from South Eastern Kenya University and co-author of the article, said: "The burden of air pollution unjustly rests on poorer populations, and women and children, as they most likely face higher exposure to pollutants and most probably experience more impacts. Thus, clean air actions will go some ways in redressing some of these inequalities in Africa, in addition to the benefits to health and the environment."

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Exposure to air pollution while in the womb is linked to adverse changes in cell processes in new-born babies

Exposure to air pollution while in the womb is linked to alterations in proteins that can be detected after a baby is born, and which affect cell processes such as autophagy, the "self-eating" of damaged cells that occurs in response to stress.

Dr Olga Gorlanova, a research physician at the University Children's Hospital, University of Basel, Switzerland, told the European Respiratory Society International Congress in Milan, Italy, that her study also showed that healthy, new-born babies had individual and different responses to their mothers' exposure to air pollution during pregnancy. This might mean that some babies were more vulnerable to it than others. This was the case even if they were born into households in areas with relatively low levels of pollution.

Earlier work by Dr Gorlanova and her colleagues had shown that exposure to air pollution during pregnancy could affect lung function and the immune system in new-borns. In the current study, they looked at proteins involved in autophagy, ageing and cell remodelling to see how prenatal exposure to air pollution could affect them.

The researchers measured 11 proteins found in the cord blood of 449 healthy new-born babies from the Bern Basel Infant Lung Development (BILD) cohort study. The BILD study, started in 1999 in Bern, aims to recruit 1000 babies by 2025. It is investigating the effects of genetics and the environment (particularly air pollution) on lung development in babies and children.

Dr Gorlanova and colleagues measured the mothers' exposure to nitrogen dioxide (NO2) and tiny particles called PM10,which areparticulate matter measuring 10 microns or less in diameter. Vehicle emissions, tyre and brake wear, and smoke are some of the sources of these pollutants. They found that NO2 and PM10 were both linked to changes in proteins involved in autophagy. Exposure to NO2 was linked to a decrease in the activity of the proteins SIRT1 and IL-8, and an increase in levels of the Beclin-1 protein.

"Our results indicate that NO2, a pollutant formed mainly from traffic emissions, is associated with increased levels of Beclin-1 protein, which is central to initiating autophagy. Exposure to higher NO2 was also linked to decreased levels of SIRT1, which is a protein that plays a protective role in stress resistance, inflammation and aging. IL-8 is a protein active in certain inflammatory cells," said Dr Gorlanova.

"We grouped the babies into four distinct clusters according to the levels of air pollution they were exposed to while in the womb. The four clusters all had similar concentrations of the proteins being studied but had differences their exposure to NO2 and PM10 air pollution. One cluster had low concentrations of nine proteins, while another cluster, consisting of seven percent of all the babies, had higher levels of proteins that are involved in inflammatory and remodelling processes: IL-8 and IL-1B. Both these groups of new-borns had been exposed to lower, although differing, levels of prenatal air pollution than the other two groups. Our findings suggest that healthy new-borns have an individual response pattern to air pollution. We think that this may be an indication that some babies are more vulnerable to it than others.

"Additionally, our work adds to the growing body of evidence that autophagy-related mechanisms may be involved in how human cells react to air pollution. The findings are consistent with evidence from tissue and animal research. Further exploration of these mechanisms may help to better understand the deleterious effects of pollution on infants."

The researchers plan to examine whether babies with distinct protein response patterns to air pollution will suffer from more breathing problems during infancy and childhood compared to those that do not show the same protein responses.

Professor Marielle Pijnenburg, associate professor of pediatric pulmonology and head of the Department of Pediatric Respiratory Medicine and Allergology at Erasmus Medical Center, Rotterdam, The Netherlands, is head of the ERS group on paediatrics and was not involved with the research. She commented: "This study adds to the growing body of evidence that air pollution can affect the health of children before and after they are born. It contributes to other research showing that autophagy-related mechanisms may be involved in how human cells react to air pollution. We need to know more about how these mechanisms can affect the health of lungs, and we need to understand why some new-borns seem to be more susceptible to air pollution than others.

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Wildfires and farming activities may be top sources of air pollution linked to increased risk, cases of dementia

No amount of air pollution is good for the brain, but wildfires and the emissions resulting from agriculture and farming in particular may pose especially toxic threats to cognitive health, according to new research from the University of Michigan.

Increasingly, evidence shows exposure to air pollution makes the brain susceptible to dementia. And now the findings of Boya Zhang and Sara Adar, environmental epidemiology researchers in U-M's School of Public Health, point to a strong likelihood that agriculture and wildfires, with their release of a range of harmful emissions at high concentrations, need to be more closely studied and monitored for their risks to public health, specifically dementia.

"We saw in our research that all airborne particles increased the risk of dementia but those generated by agricultural settings and wildfires seemed to be especially toxic for the brain," said Adar, associate chair of the Department of Epidemiology in the School of Public Health. She currently leads several large cohort studies on the impacts of exposures on cognitive aging and dementia.

"Our findings indicate that lowering levels of particulate matter air pollution, even in a relatively clean country like the United States, may reduce the number of people developing dementia in late life," Adar said.

Adar and Zhang's paper, "Comparison of Particulate Air Pollution From Different Emission Sources and Incident Dementia in the U.S.," appears today in the Journal of the American Medical Association's Internal Medicine.

Zhang, a research fellow who focuses on the effects of air pollution on cardiopulmonary disease and cognitive aging, said: "This work suggests that particulate matter air pollution from agriculture and wildfires might be more neurotoxic compared with other sources. However, more research is needed to confirm these effects, especially for these two sources which have received less attention in prior research."

"Given that the development of dementia could take a long time, this study mainly aimed to provide evidence for policymakers to reduce exposures to these sources of emissions," Zhang said.

The findings come as unusually poor air quality is regularly triggering alerts in the U.S. The alerts are aimed at protecting the public from the unseen, swirling mix of microscopic toxins in air pollution, specifically fine particulate matter or PM2.5. It is one of the most concerning elements of air pollution. At less than 2.5 microns in size, PM2.5 is less than the width of a human hair. Because it's so small, it can enter the brain through the nose directly or cross the blood-brain barrier in other ways. PM2.5 is also known to affect the lungs, heart, and in emerging research, the brain and cognitive function.

"These findings are quite timely given the increasing frequency of wildfire smoke in our

communities," Adar said. "Our data suggest that in addition to some of the more obvious health impacts of wildfire smoke like irritation to our throats and eyes along with breathing difficulties, high smoke days might also be taking a toll on our brains."

The record number of air quality alerts in the U.S. this year are due in large part to smoke from wildfires burning in Canada since May. The effect of wildfire is not new in the U.S., especially given the fires in the western part of the country.

Adar, a long-time environmental epidemiologist, said that wildfire smoke is becoming a more widespread stressor with many cities experiencing 30-plus days each year impacted by smoke. Given the extremely high levels of exposure to the public, wildfires are thought to contribute up to 25% of fine particulate matter exposures over a year across the U.S. and as much as 50% in some western regions of the country, Adar said.

"While individual wildfires may be short-lived, these events are becoming more frequent in our communities due to warmer temperatures, drier conditions, and longer fire seasons. As we've seen, wildfire smoke can also travel very far distances," Adar said.

Their findings are based on research into the development of dementia among nearly 30,000 adults from across the U.S. over an 18-year period. The data comes from the Health and Retirement Study, a nationally-representative collection of cohorts of older adults who have been followed since 1992. Pollution estimates in Adar and Zhang's study were based on home addresses of participants. Participants have been interviewed biennially about their cognition, overall health, and health behaviors until death or loss of contact for the survey.

They observed that higher levels of particulate matter air pollution, especially from agriculture and wildfires, were associated with greater risks of dementia. The findings could not be explained by other factors such as individual, neighborhood, socioeconomic status, occupation, or hometown or region of the country.

"With the knowledge of which sources are more toxic than others, it may be possible to design interventions for specific sources as a more effective way to decrease the burden of dementia," Zhang said.

Dementia is currently the seventh leading cause of death and one of the major causes of disability and dependency for older people, according to the World Health Organization.

The research specifically sought to test the hypothesis that a variation in emission sources could explain which are most toxic, but measuring the emissions with their distinct physical and chemical characteristics is challenging.

Past studies analyzing exposures to source specific fine particulate matter meant researchers mainly investigated relationships with the total mass of fine particulate matter in the air.

"In our study, we used a sophisticated prediction model that includes information about the chemical transformations and dispersion of pollution from different sources to estimate the levels of source-specific particulate matter air pollution at participants' residential addresses," Zhang said. "This approach is beneficial because it not only accounts for pollution directly emitted by a source but also pollution generated through reactions with other chemicals in the air."

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Shutting down nuclear power could increase air pollution

Nearly 20 percent of today's electricity in the United States comes from nuclear power. The U.S. has the largest nuclear fleet in the world, with 92 reactors scattered around the country. Many of these power plants have run for more than half a century and are approaching the end of their expected lifetimes.

Policymakers are debating whether to retire the aging reactors or reinforce their structures to continue producing nuclear energy, which many consider a low-carbon alternative to climate-warming coal, oil, and natural gas.

Now, MIT researchers say there's another factor to consider in weighing the future of nuclear power: air quality. In addition to being a low carbon-emitting source, nuclear power is relatively clean in terms of the air pollution it generates. Without nuclear power, how would the pattern of air pollution shift, and who would feel its effects?

The MIT team took on these questions in a new study appearing in Nature Energy. They lay out a scenario in which every nuclear power plant in the country has shut down, and consider how other sources such as coal, natural gas, and renewable energy would fill the resulting energy needs throughout an entire year.

Their analysis reveals that indeed, air pollution would increase, as coal, gas, and oil sources ramp up to compensate for nuclear power's absence. This in itself may not be surprising, but the team has put numbers to the prediction, estimating that the increase in air pollution would have serious health effects, resulting in an additional 5,200 pollution-related deaths over a single year.

If, however, more renewable energy sources become available to supply the energy grid, as they are expected to by the year 2030, air pollution would be curtailed, though not entirely. The team found that even under this heartier renewable scenario, there is still a slight increase in air pollution in some parts of the country, resulting in a total of 260 pollution-related deaths over one year.

When they looked at the populations directly affected by the increased pollution, they found that Black or African American communities -- a disproportionate number of whom live near fossil-fuel plants -- experienced the greatest exposure.

"This adds one more layer to the environmental health and social impacts equation when you're thinking about nuclear shutdowns, where the conversation often focuses on local risks due to accidents and mining or long-term climate impacts," says lead author Lyssa Freese, a graduate student in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS).

"In the debate over keeping nuclear power plants open, air quality has not been a focus of that discussion," adds study author Noelle Selin, a professor in MIT's Institute for Data, Systems, and Society (IDSS) and EAPS. "What we found was that air pollution from fossil fuel plants is so damaging, that anything that increases it, such as a nuclear shutdown, is going to have substantial impacts, and for some people more than others."

The study's MIT-affiliated co-authors also include Principal Research Scientist Sebastian Eastham and Guillaume Chossière SM '17, PhD '20, along with Alan Jenn of the University of California at Davis.

Future phase-outs

When nuclear power plants have closed in the past, fossil fuel use increased in response. In 1985, the closure of reactors in Tennessee Valley prompted a spike in coal use, while the 2012 shutdown of a plant in California led to an increase in natural gas. In Germany, where nuclear power has almost completely been phased out, coal-fired power increased initially to fill the gap.

Noting these trends, the MIT team wondered how the U.S. energy grid would respond if nuclear power were completely phased out.

"We wanted to think about what future changes were expected in the energy grid," Freese says. "We knew that coal use was declining, and there was a lot of work already looking at the impact of what that would have on air quality. But no one had looked at air quality and nuclear power, which we also noticed was on the decline."

In the new study, the team used an energy grid dispatch model developed by Jenn to assess how the U.S. energy system would respond to a shutdown of nuclear power. The model simulates the production of every power plant in the country and runs continuously to estimate, hour by hour, the energy demands in 64 regions across the country.

Much like the way the actual energy market operates, the model chooses to turn a plant's production up or down based on cost: Plants producing the cheapest energy at any given time are given priority to supply the grid over more costly energy sources.

The team fed the model available data on each plant's changing emissions and energy costs throughout an entire year. They then ran the model under different scenarios, including: an energy grid with no nuclear power, a baseline grid similar to today's that includes nuclear power, and a grid with no nuclear power that also incorporates the additional renewable sources that are expected to be added by 2030.

They combined each simulation with an atmospheric chemistry model to simulate how each plant's various emissions travel around the country and to overlay these tracks onto maps of population density. For populations in the path of pollution, they calculated the risk of premature death based on their degree of exposure.

System response

Their analysis showed a clear pattern: Without nuclear power, air pollution worsened in general, mainly affecting regions in the East Coast, where nuclear power plants are mostly concentrated. Without those plants, the team observed an uptick in production from coal and gas plants, resulting in 5,200 pollution-related deaths across the country, compared to the baseline scenario.

They also calculated that more people are also likely to die prematurely due to climate impacts from the increase in carbon dioxide emissions, as the grid compensates for nuclear power's absence. The climate-related effects from this additional influx of carbon dioxide could lead to 160,000 additional deaths over the next century.

"We need to be thoughtful about how we're retiring nuclear power plants if we are trying to think about them as part of an energy system," Freese says. "Shutting down something that doesn't have direct emissions itself can still lead to increases in emissions, because the grid system will respond."

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Study into global daily air pollution shows almost nowhere on Earth is safe

In a world first study of daily ambient fine particulate matter (PM2.5) across the globe, a Monash University study has found that only 0.18% of the global land area and 0.001% of the global population are exposed to levels of PM2.5 - the world's leading environmental health risk factor - below levels of safety recommended by Word Health Organisation (WHO).

Importantly while daily levels have reduced in Europe and North America in the two decades to 2019, levels have increased Southern Asia, Australia, New Zealand, Latin America and the Caribbean, with more than 70% of days globally seeing levels above what is safe.

A lack of pollution monitoring stations globally for air pollution, has meant a lack of data on local, national, regional and global PM2.5 exposure. Now this study, led by Professor Yuming Guo, from the Monash University School of Public Health and Preventive Medicine, and published in the journal, Lancet Planetary Health, has provided a map of how PM2.5 has changed across the globe in the past decades.

The research team utilised traditional air quality monitoring observations, satellite-based meteorological and air pollution detectors, statistical and machine learning methods to more accurately assess PM2.5 concentrations globally, according to Professor Guo.

"In this study, we used an innovative machine learning approach to integrate multiple meteorological and geological information to estimate the global surface-level daily PM2.5 concentrations at a high spatial resolution of approximately 10km ×10km for global grid cells in 2000-2019, focusing on areas above 15 μg/m³ which is considered the safe limit by WHO (The threshold is still arguable)," he said.

The study reveals that annual PM2.5 concentration and high PM2.5 exposed days in Europe and northern America decreased over the two decades of the study -- whereas exposures increased in southern Asia, Australia and New Zealand, and Latin America and the Caribbean.

In addition, the study found that:

•     Despite a slight decrease in high PM2.5 exposed days globally, by 2019 more than 70% of days still had PM2.5 concentrations higher than 15 μg/m³.
•     In southern Asia and eastern Asia, more than 90% of days had daily PM2.5 concentrations higher than 15 μg/m³.
•     Australia and New Zealand had a marked increase in the number of days with high PM2.5 concentrations in 2019.
•     Globally, the annual average PM2.5 from 2000 to 2019 was 32.8 µg/m3.
•     The highest PM2.5 concentrations were distributed in the regions of Eastern Asia (50.0 µg/m3) and Southern Asia (37.2 µg/m3), followed by northern Africa (30.1 µg/m3).
•     Australia and New Zealand (8.5 μg/m³), other regions in Oceania (12.6 μg/m³), and southern America (15.6 μg/m³) had the lowest annual PM2.5 concentrations.
•     Based on the new 2021 WHO guideline limit, only 0.18% of the global land area and 0.001% of the global population were exposed to an annual exposure lower than this guideline limit (annual average of 5 μg/m³) in 2019.

According to Professor Guo, the unsafe PM2.5 concentrations also show different seasonal patterns "included Northeast China and North India during their winter months (December, January, and February), whereas eastern areas in northern America had high PM2.5 in its summer months (June, July, and August)," he said.

"We also recorded relatively high PM2.5 air pollution in August and September in South America and from June to September in sub-Saharan Africa."

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Study links adoption of electric vehicles with less air pollution and improved health

Electric vehicles are widely hailed as a key way to mitigate climate change through reduced emissions, but research on the dual benefits of reduced air pollution and improved health has been largely hypothetical.

A team of researchers from the Keck School of Medicine of USC have now begun to document the actual impact of electric vehicle adoption in the first study to use real-world data to link electric cars, air pollution and health. Leveraging publicly available datasets, the researchers analyzed a "natural experiment" occurring in California as residents in the state rapidly transitioned to electric cars, or light-duty zero emissions vehicles (ZEVs). The results were just published in the journal Science of the Total Environment.

The team compared data on total ZEV registration, air pollution levels and asthma-related emergency room visits across the state between 2013 to 2019. As ZEV adoption increased within a given zip code, local air pollution levels and emergency room visits dropped.

"When we think about the actions related to climate change, often it's on a global level," said Erika Garcia, PhD, MPH, an assistant professor of population and public health sciences at the Keck School of Medicine and the study's lead author. "But the idea that changes being made at the local level can improve the health of your own community could be a powerful message to the public and to policy makers."

The researchers also found that while total ZEVs increased over time, adoption was considerably slower in low-resource zip codes -- what the researchers refer to as the "adoption gap." That disparity points to an opportunity to restore environmental justice in communities that are disproportionately affected by pollution and related health problems.

"The impacts of climate change on health can be challenging to talk about because they can feel very scary," said Sandrah Eckel, PhD, an associate professor of population and public health sciences at the Keck School of Medicine and the study's senior author. "We're excited about shifting the conversation towards climate change mitigation and adaptation, and these results suggest that transitioning to ZEVs is a key piece of that."

Benefits for health and the climate

To study the effects of electric vehicle adoption, the research team analyzed and compared four different datasets. First, they obtained data on ZEVs (which includes battery electric, plug-in hybrid, and hydrogen fuel cell cars) from the California Department of Motor Vehicles and tabulated the total number registered in each zip code for every year between 2013 and 2019.

They also obtained data from U.S. Environmental Protection Agency air monitoring sites on levels of nitrogen dioxide (NO2), an air pollutant related to traffic, and zip code level asthma-related visits to the emergency room. Asthma is one of the health concerns long linked with air pollutants such as NO2, which can also cause and exacerbate other respiratory diseases, as well as problems with the heart, brain and other organ systems.

Finally, the researchers calculated the percentage of adults in each zip code who held bachelor's degrees. Educational attainment levels are frequently used as an indicator of a neighborhood's socioeconomic status.

At the zip code level, for every additional 20 ZEVs per 1,000 people, there was a 3.2% drop in the rate of asthma-related emergency visits and a small suggestive reduction in NO2 levels. On average across zip codes in the state, ZEVs increased from 1.4 to 14.6 per 1,000 people between 2013 and 2019. ZEV adoption was significantly lower in zip codes with lower levels of educational attainment. For example, a zip code with 17% of the population having a bachelor's degree had, on average, an annual increase of 0.70 ZEVs per 1,000 people compared to an annual increase of 3.6 ZEVs per 1,000 people for a zip code with 47% of the population having a bachelor's degree.

Past research has shown that underserved communities, such as lower-income neighborhoods, tend to face worse pollution and associated respiratory problems than more affluent areas. If ZEVs replace gas-powered cars in those neighborhoods, they could stand to benefit substantially.

"Should continuing research support our findings, we want to make sure that those communities that are overburdened with the traffic-related air pollution are truly benefiting from this climate mitigation effort," Garcia said.

More to learn

While climate change is a massive health threat, mitigating it offers a massive public health opportunity, Eckel said. As one of the first studies to quantify the real-world environmental and health benefits of ZEVs, the research can help demonstrate the power of this mitigation measure, including possibly reduced health care utilization and expenditures.

The findings are promising, Garcia said, but many questions remain. Future studies should consider additional impacts of ZEVs, including emissions related to brake and tire wear, mining of materials for their manufacture, and disposal of old cars. The researchers also hope to study additional types of pollutants and other classes of vehicles, in addition to conducting a follow-up study of the effects of the ever-growing share of ZEVs in the state.

Moving forward, transitioning to ZEVs is just one part of the solution, Eckel said. Shifting to public transport and active transport, including walking and biking, are other key ways to boost environmental and public health.

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Simple measures can go a long way to combating air pollution in schools

Most UK primary schools experience levels of pollution which exceed the safe levels set out by the World Health Organization, yet simple measures can cut outdoor and indoor exposure of toxins by almost half, according to a new study from the University of Surrey.

Working with a select number of London schools, researchers from Surrey's Global Centre for Clean Air Research (GCARE) investigated whether putting up a green screen along the perimeter fence of a school, installing air purifiers in classrooms, and organising school street initiatives during pick-up and drop-off hours, improved air quality of classrooms and playgrounds. These initiatives were funded by Impact on Urban Health.

The researchers found that air purifiers in classrooms reduced indoor pollution concentrations by up to 57%, and the School Streets initiative, which stops motor vehicles driving past schools at the start and end of school days, reduced particle concentrations by up to 36%. Green screens at the school boundary reduced some of the most dangerous outdoor particle levels coming from roads by up to 44%, depending on wind conditions.

Prashant Kumar, founding Director of the Global Centre for Clean Air Research (GCARE) at the University of Surrey, said:

"Everybody, especially our children, deserves to live and work where the air is as clean and safe as possible. Unfortunately, the reality is far from ideal, with many of our schools unwittingly exposing children to harmful pollutants. The problem is particularly bad at schools near busy roads.

"Our research offers hope to many who care about this issue, as the results show that taking reasonable action can make a positive difference."

Ten million students worldwide spend 30% of their daily lives at school, with 70% of this time being spent indoors. Currently, 7,000 UK schools breach the World Health Organization's air quality limits, leaving children vulnerable to respiratory diseases, affected lung and brain health, behavioural problems, and increased risk of cancer.

Kate Langford, Programme Director of the Health Effects of Air pollution programme at Impact on Urban Health, funders of the research, said:

"Every child has the right to learn in an environment that keeps them safe and healthy. But, every day, children are exposed to dangerously high levels of air pollution in and around schools.

"Our partnership with Arup, Global Action Plan and the University of Surrey has shown there are practical ways that we can protect children in and around schools and can help guide schools to implement these solutions.

"These measures now need to be combined with efforts from local authorities at regional and national levels to improve air quality and create healthier places for children to live, learn and play."

Larissa Lockwood, Director of Clean Air at Global Action Plan, said:

"Schools should be safe places of learning, not places where students are at risk of health hazards. There is no safe level of air pollution, but children are particularly vulnerable to its impacts including the development of organs and their ability to learn. Services like the London Schools Pollution Helpdesk ensure that schools have access to advice on what they can do to reduce exposure to air pollution, including the measures tested in this research. But this needs to be rolled out nationally -- all children must be protected from the health effects of air pollution in their everyday lives."

Professor Prashant Kumar concluded:

"My simple plea to decision-makers in the UK is this: simple actions speak louder than words. By giving every school resources to implement one of the measures detailed in our research, they could make a world of difference to tens of thousands of children in this country."

Read more at Science Daily

Air pollution, including during wildfires, shows ill effects in children

New research linking air pollution data from federal monitors in the Sacramento area of California, including during significant fires, is showing ill effects of pollution exposure among children, a new University of California, Davis, study suggests.

Blood samples show that children have elevated markers of inflammation, such as interleukin 6, if they were exposed to higher air pollution. Further, higher air pollution was linked to lower cardiac autonomic regulation in children, which impacts how fast the heart beats and how hard it pumps, according to the study.

In the study, published Aug. 3 date in the journal New Directions for Child and Adolescent Research, researchers looked at blood samples from more than 100 healthy children ages 9-11 in the Sacramento area where pollutants near their homes were recorded by the Environmental Protection Agency. The study was authored by Anna M. Parenteau, a doctoral student, and Camelia E. Hostinar, associate professor, both from the UC Davis Department of Psychology. The work took place at UC Davis.

These findings are important because exposure to pollutants released during wildfires has been related to numerous negative health outcomes in children, who have smaller bodies and organ systems than adults, including asthma and decreased lung function, as well as neurodevelopmental outcomes like attention deficit hyperactivity disorder, autism, and deficits in school performance and memory, researchers said.

Looked at particulates

Researchers looked at fine particulate matter data from the EPA (PM2.5) -- or the fine particles that can penetrate lungs and pass into the bloodstream -- finding the children's blood contained markers of systemic inflammation. Additionally, PM2.5, which refers to particulate matter measuring 2.5 micrometers or smaller by the EPA, was linked to lower cardiac autonomic regulation assessed using an electrocardiogram. Specifically, researchers used data files maintained by the EPA, which have daily air quality summary information from each outdoor monitor in the country.

In total, 27 of the children studied had inflammation markers in their blood recorded during significant fires when their neighborhoods recorded significant levels of PM2.5 in the air. These times when fires were burning included during the Mendocino Complex Fire in 2018, which was active about 100 miles from the lab where blood was drawn. The findings were similar to those found in an earlier study, in which the blood of young primates was collected by UC Davis researchers after significant wildfires.

"By examining daily and monthly levels of particulate matter in relation to children's inflammation and autonomic physiology, this study further demonstrates the immediate consequences of exposure to air pollution, which may increase risk of future disease," Parenteau said. Furthermore, Parenteau added: "As climate change continues to impact children and families, it is paramount to understand the impact of environmental contaminants such as air pollution on children's physiology."

Previous studies with children have shown significant associations between ambient air pollution and allergic sensitization, respiratory symptoms, and ultra-structural and cellular changes to their lungs and airways, researchers said.

Researchers have found children may be especially susceptible to the effects of air pollution, given that, compared to adults, they have a higher intake of contaminants and greater lung surface area relative to their body weight.

Continued developmental research on environmental contaminants can sound the alarm about the effects of air pollution and inform policy changes that could promote long-term population health, researchers concluded.

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Air pollution caused 2,780 deaths, illnesses, and IQ loss in children in Massachusetts in 2019

Air pollution remains a silent killer in Massachusetts, responsible for an estimated 2,780 deaths a year and for measurable cognitive loss in Bay State children exposed to fine particulate pollutants in the air they breathe, according to a new study by researchers at Boston College's Global Observatory on Planetary Health.

The study was supported by the Barr Foundation and is the first to examine far-reaching public health consequences of air pollution in the state on a town-by-town basis. The study found air-pollution-related disease, death and IQ loss occur in every city and town regardless of demographics or income level. Highest rates were in the most economically disadvantaged and socially underserved cities and towns.

The Boston College team estimates the cumulative impact on childhood cognitive development in Massachusetts in 2019 was a loss of almost 2 million Performance IQ points, or more than 2 IQ points for the average child, according to the report, published today in the journal Environmental Health. IQ loss impairs children's school performance and reduces graduation rates, the team noted.

"We are talking about the impacts of air pollution at a very local level in Massachusetts -- not just statewide," said lead author Boston College Professor of Biology Philip J. Landrigan, MD, director of the Observatory. "This report gives the people in every city and town the opportunity to see for themselves the quality of the air they and their families are breathing and the dangerous health implications for both adults and children as a consequence of air pollution."

"All of these health effects occurred at pollution levels below current EPA standards," Landrigan noted.

The average level of fine particulate pollution across Massachusetts in 2019 was 6.3 micrograms per cubic meter, and levels ranged from a low of 2.77 micrograms per cubic meter in Worcester County to a high of 8.26 in Suffolk County. The U.S. Environmental Protection Agency standard is 12 micrograms per cubic meter, and the World Health Organization's recommended guideline is 5.

"Clearly, current EPA air pollution standards are not adequately protecting public health," Landrigan said.

Town-by-town air pollution information is not typically available, given there are not enough air quality monitoring stations in the state. The team determined levels for all cities and towns using available data and computer modeling.

While Massachusetts meets federal clean air guidelines and air pollution in the U.S. has declined 70 percent since the passage of the Clean Air Act in the 1970s -- when Landrigan and other scientists successfully pushed for the removal of lead from gasoline -- unclean air at current levels still poses health hazards to both healthy individuals and those with other ailments or illnesses.

"We do not have the level of air pollution you see in China or India and because it is mostly invisible today people tend to forget about air pollution and we get complacent," Landrigan said. "We hope to break through this complacency and increase awareness. Air pollution is killing 2,780 people in Massachusetts each year, nearly 5 percent of all deaths in the state, and that is a big deal. Air pollution is something we can fix. We know the steps that need to be taken to reduce fatalities and the impact on our children and grandchildren. Now citizens in every city and town across the Commonwealth need to urge our elected officials to take those necessary steps."

Additional findings include:
 

• Of the 2,780 deaths attributable to air pollution in Massachusetts in 2019, at least 2,185 were due to lung cancer 1,677 to heart disease, 343 to chronic lung disease, and 200 to stroke.
• Air pollution was responsible for 15,386 cases of pediatric asthma and an estimated 308 low-birthweight babies (5.5 lbs. or less).

More than 95 percent of air pollution in Massachusetts results from the combustion of fossil fuels. Cars, trucks, buses, planes, trains and ships produced two-thirds of pollutant emissions-655,000 tons -- in 2017, the most recent year for which data were available. Power plants, industrial facilities, and home heating and cooking produced 283,000 tons. In all, these sources emitted 938,000 tons of pollutants.

Fossil fuel combustion is also the major source of the carbon dioxide and other greenhouse gases that drive global climate change, which the researchers said should further incentivize Massachusetts to reduce air pollution and greenhouse gas emissions by transitioning to cleaner fuels.

"Air pollution harms our environment and young people, and these burdens disproportionately impact environmental justice communities," said Kathryn Wright, the Barr Foundation's Senior Program Officer for Clean Energy. "Meaningful action on climate change requires us to swiftly address air pollution from transportation and our energy system and its many harmful effects."

Fine particulate air pollution is linked to multiple non-communicable diseases in adults, including cardiovascular disease, stroke, lung cancer and diabetes. Among infants and children air pollution increases risk for premature birth, low birthweight, stillbirth, impaired lung development, and asthma.

"All of these adverse health effects occur at fine particulate matter pollution levels below the U.S. Environmental Protection Agency's current annual standard of 12 micrograms per cubic meter," said Landrigan. "So even for a state like Massachusetts, which registered below that standard, air pollution is a formidable public health threat that needs urgently to be addressed."

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Link between air pollution and child brain development strengthened

Air pollution is not just a problem for lungs. Increasingly, research suggests air pollution can influence childhood behavioral problems and even IQ. A new study led by the University of Washington has added evidence showing that both prenatal and postnatal exposure to air pollution can harm kids.

The study, published in Environmental Health Perspectives, found that children whose mothers experienced higher nitrogen dioxide (NO2) exposure during pregnancy, particularly in the first and second trimester, were more likely to have behavioral problems.

Researchers also reported that higher exposures to small-particle air pollution (PM2.5) when children were 2 to 4 years old was associated with poorer child behavioral functioning and cognitive performance.

"Even in cities like Seattle or San Francisco, which have a lot of traffic but where the pollution levels are still relatively low, we found that children with higher prenatal NO2 exposure had more behavioral problems, especially with NO2exposure in the first and second trimester," said Yu Ni, lead author and a postdoctoral scholar in the Department of Environmental & Occupational Health Sciences.

The study involved data gathered from 1,967 mothers recruited during pregnancy from six cities: Memphis, Tennessee; Minneapolis; Rochester, N.Y.; San Francisco; and two in Washington, Seattle and Yakima. Originally, these participants were enrolled as part of three separate studies: CANDLE, GAPPS and TIDES. The three studies have been combined under a major NIH initiative called ECHO, which brings together multiple pregnancy cohorts to address key child health concerns. These three combined cohorts are known as the ECHO PATHWAYS consortium.

The study employed a state-of-the-art model of air pollution levels in the United States over time and space that was developed at the University of Washington. Using participant address information, the researchers were able to estimate each mother and child's exposures during the pregnancy period and early childhood.

Exposure to NO2 and PM2.5 pollution in early life is important to understand, Ni said, because "there are known biological mechanisms that can link a mother's inhalation of these pollutants to effects on placenta and fetal brain development."

Furthermore, once the child is born, the first few years are a critical time of ongoing brain development as the number of neural connections explodes and the brain reaches 90% of its future adult size, the researchers write. For young children, inhaled pollutants that invade deep in the lung and enter the central nervous system can cause damage in areas relevant for behavioral and cognitive function.

"This study reinforces the unique vulnerability of children to air pollution -- both in fetal life where major organ development and function occurs as well as into childhood when those processes continue. These early life perturbations can have lasting impacts on lifelong brain function. This study underscores the importance of air pollution as a preventable risk factor for healthy child neurodevelopment," said senior author Dr. Catherine Karr, a professor in the UW School of Public Health and School of Medicine.

More specifically, the researchers found that exposure to PM2.5 pollution was generally associated with more behavioral problems in girls than in boys, and that the adverse effect of PM2.5 exposure in the second trimester on IQ was stronger in boys.

"We hope the evidence from this study will contribute to informed policymaking in the future," Ni said. "In terms of reducing air pollution, the U.S. has gone a long way under the Clean Air Act, but there are threats to continued improvement in the nation's air quality. The evidence suggests there is reason to bring the level of air pollution down even further as we better understand the vulnerability of pregnant women and children."

Read more at Science Daily

Reducing air pollution can support healthy brain development

A new study finds that having a portable air cleaner in the home can reduce the negative impacts of air pollution on brain development in children.

Simon Fraser University researchers collaborated with U.S. and Mongolian scientists to study the benefits of using air filters to reduce exposure to air pollution during pregnancy, and assessed the impact on children's intelligence.

The researchers note that their randomized controlled trial is the first study of its kind to document the impacts of air pollution reduction on cognition in children.

Beginning in 2014, the team recruited 540 pregnant women in Ulaanbaatar, Mongolia to participate in the Ulaanbaatar Gestation and Air Pollution Research (UGAAR) study. Ulaanbaatar has some of the worst air quality in the world, well exceeding guidelines set by the World Health Organization (WHO).

The women were less than 18 weeks into their pregnancies and non-smokers who had not previously used air filtering devices in their homes. They were randomly assigned to either the control or intervention group. The intervention group was provided with one or two HEPA filter air cleaners and encouraged to run the air cleaners continuously for the duration of their pregnancies. The air cleaners were removed from the home once the child was born.

The researchers later measured the children's full-scale intelligence quotient (FSIQ) at four years of age using the Weschler Preschool and Primary Scale of Intelligence.

They found that the children born to mothers who had used the air cleaners had an average FSIQ that was 2.8-points higher than the group that did not use an air cleaner during pregnancy.

"These results, combined with evidence from previous studies, strongly implicate air pollution as a threat to brain development," says Ryan Allen, professor of environmental health in SFU's Faculty of Health Sciences. "But the good news is that reducing exposure had clear benefits."

Children in the intervention group also had significantly greater average verbal comprehension index scores, which is consistent with results from previous observational studies. The research suggests that a child's verbal skills may be particularly sensitive to air pollution exposure.

More than 90 per cent of the world's population breathes air with particulate matter concentrations above the WHO guidelines. The researchers suggest the population-level impact of air pollution on brain development could be substantive even if the individual-level effects are modest.

Their study results indicate that reducing exposure to air pollution during pregnancy could improve children's cognitive development around the world.

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Preadolescents exposed to high levels of air pollution in their first years of life display changes in brain connectivity

Higher exposure to air pollution is associated with higher functional brain connectivity among several brain regions in preadolescents, while exposure to traffic noise was not, according to a study led by ISGlobal, an institution supported by "la Caixa" Foundation. The findings also identify the first years of life as the most sensitive period of exposure to air pollution.

Traffic-related air pollution and noise are affecting an increasing number of people worldwide. "We already know that children are particularly vulnerable to the effect of these exposures, because of their immature metabolism and developing brain," says ISGlobal researcher and senior author Mónica Guxens. In fact, several studies by Guxens and others have found an association between exposure to traffic-related air pollution during early childhood and alterations in the brain structure.

In this study, the research team used magnetic resonance imaging (MRI) to explore whether higher exposure to air pollution or noise could also be associated with possible alterations in brain connectivity (i.e. the way in which different brain regions interact). "The use of MRI has opened up new possibilities in epidemiological research for investigating the structure and the functioning of the brain," says Guxens.

The researchers used data of 2,197 children from the Generation R Study, born between April 2002 and Jan 2006 and living in Rotterdam, the Netherlands. Using land use models, they estimated levels of nitrogen oxides (NOx and NO2) and particulate matter (PM) at the participants' homes at different time periods: during pregnancy, from birth to 3 years, from 3 to 6 years, and from 6 years of age to the age at which the MRI scan was performed. Noise levels due to traffic road were estimated using existing noise maps. Between 9 and 12 years of age, the participants were invited to undergo an MRI scan in the resting state (i.e. with no external stimuli).

The findings show that higher exposures to NO2 and PM2.5 absorbance (an indicator of black carbon particles) from birth to 3 years, and to NOx from 3 to 6 years of age were associated with higher functional brain connectivity among several brain regions in the preadolescents. The associations were identified in brain areas predominantly involved in two networks that have strongly opposing functions: the task negative (or "default-mode") network tends to be activated in resting conditions and the task positive network tends to be activated during tasks that demand attention. "We still have to understand the consequences of this increased activity of both networks in resting conditions, but for now we can say that the brain connectivity in children exposed to higher levels of air pollution is different from what we would expect," says Laura Pérez-Crespo, first author of the study.

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High air pollution from fracking in Ohio county

Some residents of Belmont County in eastern Ohio have long suffered from headaches, fatigue, nausea and burning sensations in their throats and noses. They suspected these symptoms were the result of air pollution from fracking facilities that dominate the area, but regulators dismissed and downplayed their concerns.

With the technical assistance of volunteer scientists at Columbia University's Lamont-Doherty Earth Observatory, MIT and the American Geophysical Union's Thriving Earth Exchange, local advocacy groups set up their own network of low-cost sensors. They found that the region's three EPA sensors were not providing an accurate picture: The sensors revealed concerning levels of air pollution, and correlations between local spikes and health impacts.

The results are published today in the journal Environmental Research Letters.

Nestled in an Appalachian valley, Belmont has been booming with new infrastructure to extract and process natural gas. Fracking is known to emit pollutants including particulate matter and volatile organic compounds such as benzene, toluene and ethylbenzene, which have been linked to respiratory and cardiovascular health problems. Lung and bronchus cancer have become the leading cause of cancer deaths in Ohio. A 2017 Yale Public Health analysis confirmed the need for additional monitoring and regulation for chemicals associated with unconventional oil and gas development.

Concerned about the fumes in certain areas of the community and the lack of information and transparency, two activist groups, Concerned Ohio River Residents and the Freshwater Accountability Project, wanted to set up a high-density monitoring network. After submitting their proposal to the Thriving Earth Exchange, which enables collaborations between community groups and volunteer scientists, they were paired with Garima Raheja, a PhD candidate who studies air pollution at Lamont-Doherty.

"We realized that the Thriving Earth Exchange program would give us valuable aid to validate the complaints we often receive from those living near pollution sources in a way that would provide credible and actionable data to improve air quality in the region," said Lea Harper, managing director of Freshwater Accountability Project.

With advice from Raheja and other scientists, the community members bought 60 low-cost sensors to monitor particulate matter and volatile organic compounds in the air. Then they identified areas of highest concern, and recruited residents to install and maintain the sensors in backyards, churches and schools in those areas.

The new study presents the first two years of data from the sensor network. The team found that many sites frequently experienced days when air pollution exceeded levels recommended by the World Health Organization. For example, in the city of Martins Ferry, where a sensor took measurements for 336 days, it measured unsafe levels of air pollution on 50 of those days.

"It is kind of wild," said Raheja, "considering that it's generally a clean area. I think any number of days above WHO guidelines is really concerning for an area like this."

She sees a clear link to the area's fossil fuel development. "If there wasn't fracking in this area, there would be no reason for bad air pollution. It's not an urban area. There's not a lot of cars or rush hour or anything like that which usually causes air pollution."

The study compares the daily averages collected from the citizen sensors with the EPA's three nearby sensors. The correlation between the two was low -- less than 55 percent.

"It just goes to show that the EPA monitors might be getting broad trends correctly, like annual or seasonal amounts," said Raheja. "But in terms of daily averages, which is what affects human health, the EPA sensors are not always capturing the heterogeneous exposure that people in this area experience."

That's because the EPA sensors are too few and too widely spaced to capture a detailed picture of the air pollution levels, she said. EPA relies on high-grade monitors that cost hundreds of thousands of dollars apiece, which helps explain why the network is so sparse. In contrast, the citizen scientists' sensors cost only a few hundred dollars each, so they were able to set up a denser network.

In another aspect of the study, residents picked up air pollution spikes on their monitors and wanted to know where they came from. So the volunteer scientists helped to model local wind patterns to key in on which fracking facilities could be responsible for spikes in specific sensors on specific days.

"There are a lot of different sources in the area, and sometimes community activists have to pick which battles to fight first," said Raheja. So far, residents say they are particularly concerned about the area's Williams Compressor Station and the Dominion Compressor Station.

The data have allowed community leaders to submit targeted public records requests about these operations and their compliance with air quality standards, the paper notes. Information from the air quality sensors also has helped residents know when to close their windows, wear masks or update indoor air purification systems.

Community members also saw correlations between air pollution spikes and their headaches and nausea. For example, some noticed bad smells and more severe symptoms in mid December 2020. At the same time, the air pollution data shows several spikes in emissions.

The paper quotes community member Kevin Young. "Before, [there] was no one to help us. None of the Ohio regulators would come to witness the extreme air pollution events that made my wife and me very sick." He added, "Now that we have data to substantiate the harmful amounts of the air pollutants, it seems the regulators are taking us more seriously."

The paper notes that the data offered a shared language that community members could use to articulate their complaints to the EPA, Ohio Department of Natural Resources, and the Ohio Department of Health. Regulators are starting to take notice; local activist Jill Hunkler was invited to testify in April 2021 before the U.S. House of Representatives Subcommittee on the Environment.

The scientists and community groups hope to continue working together. They are currently applying for grants to scale up their sensor network, and networking with other concerned community groups, some as far away as Louisiana's infamous Cancer Alley, who want to learn more about how to get started on similar programs.

Read more at Science Daily

Cutting air pollution emissions would save 50,000 US lives, $600 billion each year

Eliminating air pollution emissions from energy-related activities in the United States would prevent more than 50,000 premature deaths each year and provide more than $600 billion in benefits each year from avoided illness and death, according to a new study by University of Wisconsin-Madison researchers.

Published today in the journal GeoHealth, the study reports the health benefits of removing dangerous fine particulates released into the air by electricity generation, transportation, industrial activities and building functions like heating and cooking -- also major sources of carbon dioxide emissions that cause climate change, since they predominantly rely on burning fossil fuels like coal, oil, and natural gas.

"Our work provides a sense of the scale of the air quality health benefits that could accompany deep decarbonization of the U.S. energy system," says Nick Mailloux, lead author of the study and a graduate student at the Center for Sustainability and the Global Environment in UW-Madison's Nelson Institute for Environmental Studies. "Shifting to clean energy sources can provide enormous benefit for public health in the near term while mitigating climate change in the longer term."

Working with scientists specializing in air quality and public health, Mailloux used a model from the U.S. Environmental Protection Agency to determine the health benefits from a complete reduction in emissions of fine particulate matter and of sulfur dioxide and nitrogen oxides. These compounds can form particulate matter once released into the atmosphere.

These pollutants contribute to health problems such as heart disease, stroke, chronic obstructive pulmonary disease, lung cancer and lower respiratory infections that can dramatically shorten lifespans. Doing away with these pollutants would save about 53,200 lives each year in the US, providing about $608 billion in benefits from avoided healthcare costs and loss of life, according to the researchers' analysis.

The researchers also studied the health effects if regions of the country were to act independently to reduce emissions instead of as part of a concerted nationwide effort. The effects can differ widely in different parts of the US, in part because of regional variations in energy use and population.

The Southwest, a region comprising Arizona, California and Nevada, would retain 95 percent of the benefits if it moved alone to eliminate fine particle emissions.

"In the Mountain region, though, most of the benefit of emissions removal is felt somewhere else," Mailloux says. "Just 32 percent of the benefit remains in states in the Mountain region. This is partly because there are large population centers downwind of the Mountain region that would also benefit."

Every region of the country sees more benefit from nationwide action than from acting on their own to reduce emissions.

"The Great Plains, for example, gets more than twice as much benefit from nationwide efforts as it does from acting alone," says Mailloux. "The more that states and regions can coordinate their emissions reductions efforts, the greater the benefit they can provide to us all."

The researchers hope that by describing the near-term payoffs on top of the threats of more distant climate impacts, the new study motivates more action on climate change.

Read more at Science Daily

Pacific Northwest wildfires alter air pollution patterns across North America

Increasingly large and intense wildfires in the Pacific Northwest are altering the seasonal pattern of air pollution and causing a spike in unhealthy pollutants in August, new research finds. The smoke is undermining clean air gains, posing potential risks to the health of millions of people, according to the study.

The research, led by scientists at the National Center for Atmospheric Research (NCAR), found that levels of carbon monoxide -- a gas that indicates the presence of other air pollutants -- have increased sharply as wildfires spread in August. Carbon monoxide levels are normally lower in the summer because of chemical reactions in the atmosphere related to changes in sunlight, and the finding that their levels have jumped indicates the extent of the smoke's impacts.

"Wildfire emissions have increased so substantially that they're changing the annual pattern of air quality across North America," said NCAR scientist Rebecca Buchholz, the lead author. "It's quite clear that there is a new peak of air pollution in August that didn't used to exist."

Although carbon monoxide generally is not a significant health concern outdoors, the gas indicates the presence of more harmful pollutants, including aerosols (airborne particulates) and ground-level ozone that tends to form on hot summer days.

The research team used satellite-based observations of atmospheric chemistry and global inventories of fires to track wildfire emissions during most of the past two decades, as well as computer modeling to analyze the potential impacts of the smoke. They focused on three North American regions: the Pacific Northwest, the central United States, and the Northeast.

Buchholz said the findings were particularly striking because carbon monoxide levels have been otherwise decreasing, both globally and across North America, due to improvements in pollution-control technologies.

The study was published this week in Nature Communications. The research was funded in part by the U.S. National Science Foundation, NCAR's sponsor. The paper was co-authored by researchers from the University of Colorado, Boulder; Columbia University; NASA; Tsinghua University; and Colorado State University.

Increasing impacts on air pollution

Wildfires have been increasing in the Pacific Northwest and other regions of North America, due to a combination of climate change, increased development, and land use policies. The fires are becoming a larger factor in air pollution, especially as emissions from human activities are diminishing because of more efficient combustion processes in motor vehicles and industrial facilities.

To analyze the impacts of fires, Buchholz and her collaborators used data from two instruments on the NASA Terra satellite: MOPITT (Measurements of Pollution in the Troposphere), which has tracked carbon monoxide continually since 2002; and MODIS (Moderate Resolution Imaging Spectrometer), which detects fires and provides information on aerosols. They also studied four inventories of wildfire emissions, which rely on MODIS data.

The scientists focused on the period from 2002, the beginning of a consistent and long-term record of MOPPIT data, to 2018, the last year for which complete observations were available at the time when they began their study.

The results showed an increase in carbon monoxide levels across North America in August, which corresponded with the peak burning season of the Pacific Northwest. The trend was especially pronounced from 2012 to 2018, when the Pacific Northwest fire season became much more active, according to the emissions inventories. Data from the MODIS instrument revealed that aerosols also showed an upward trend in August.

To determine whether the higher pollution levels were caused by the fires, the scientists eliminated other potential emission sources. They found that carbon monoxide levels upwind of the Pacific Northwest, over the Pacific Ocean, were much lower in August -- a sign that the pollution was not blowing in from Asia. They also found that fire season in the central U.S. and the Northeast did not coincide with the August increase in pollution, which meant that local fires in those regions were not responsible. In addition, they studied a pair of fossil fuel emission inventories, which showed that carbon monoxide emissions from human activities did not increase in any of the three study regions from 2012 to 2018.

"Multiple lines of evidence point to the worsening wildfires in the Pacific Northwest as the cause of degraded air quality," Buchholz said. "It's particularly unfortunate that these fires are undermining the gains that society has made in reducing pollution overall."

Risks to human health

The findings have implications for human health because wildfire smoke has been linked to significant respiratory problems, and it may also affect the cardiovascular system and worsen pregnancy outcomes.

Buchholz and her co-authors used an NCAR-based computer model, the Community Atmosphere Model with a chemistry component, to simulate the movement of emissions from the Pacific Northwest fires and their impact on carbon monoxide, ozone, and fine particulate matter. They ran the simulations on the Cheyenne supercomputer at the NCAR-Wyoming Supercomputing Center. The results showed the pollutants could affect more than 130 million people, including about 34 million in the Pacific Northwest, 23 million in the Central U.S., and 72 million in the Northeast.

Although the study did not delve deeply into the health implications of the emissions, the authors looked at respiratory death rates in Colorado for the month of August from 2002 to 2011, compared with the same month in 2012 to 2018. They chose Colorado, located in the central U.S. region of the study, because respiratory death rates in the state were readily obtainable.

They found that Colorado respiratory deaths in August increased significantly during the 2012-2018 period, when fires in the Pacific Northwest -- but not in Colorado -- produced more emissions in August.

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How air pollution alters lung tissue, increasing cancer susceptibility

Scientists have identified a mechanism that explains how fine air pollution particles might cause lung cancer, according to a study published today in eLife.

The findings could lead to new approaches for preventing or treating the initial lung changes that lead to the disease.

Tiny, inhalable fine particulate matter (FPM) found in air pollutants has been recognised as a Group 1 carcinogen and a substantial threat to global health. However, the cancer-causing mechanism of FPM remains unclear.

"Despite its potential to cause mutations, recent research suggests that FPM does not directly promote -- and may even inhibit -- the growth of lung cancer cells," explains first author Zhenzhen Wang, an associate researcher at Nanjing University (NJU), Nanjing, China, who carried out the study between labs at NJU and the University of Macau where she was sponsored by a University of Macau Fellowship. "This suggests that FPM might lead to cancer through indirect means that support tumour growth. For example, some studies suggest FPM can prevent immune cells from moving to where they are needed."

To explore this possibility, Wang and the team collected FPM from seven locations in China and studied its effects on the main immune cells that defend against tumour growth -- called cytotoxic T-cells (CTLs). In mice administered with lung cancer cells that were not exposed to FPM, CTLs were recruited to the lung to destroy the tumour cells. By contrast, in the mice whose lungs were exposed to FPM, the infiltration of CTLs was delayed -- potentially allowing the tumour cells to establish in lung tissue.

To investigate why the CTLs did not enter the lung as quickly in the FPM-exposed lungs, the team studied both the CTLs themselves and the lung tissue structure. They found that CTLs exposed to FPM still retained their migratory ability, but that FPM exposure dramatically compressed the lung tissue structure and the spaces that immune cells move between. There were also much higher levels of collagen -- a protein that provides biomechanical support for cells and tissues. When the team studied the movement of CTLs in the mice, in lung tissue exposed to FPM, CTLs struggled to move, whereas those in the untreated tissue were able to move freely.

Further analysis of the tissue showed that the structural changes were caused by increases in a collagen subtype called collagen IV, but the team still did not know how FPM triggered this. They found the answer when they looked more closely at the structural changes to collagen IV and the enzyme responsible for making them -- called peroxidasin. This enzyme drives a specific type of cross-linking that exposure to FPM was found to cause and aggravate in the lung tissue.

"The most surprising find was the mechanism by which this process occurred," Wang says. "The peroxidasin enzyme stuck to the FPM in the lung, which increased its activity. Taken together, this means that wherever FPM lands in the lung, increased peroxidasin activity leads to structural changes in the lung tissue that can keep immune cells out and away from growing tumour cells."

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