fine particulate matter

Air pollution and human health

September 1, 2025 By EarthWise Leave a Comment

Climate change is making air quality worse in many parts of the world. Rising temperatures increase ground-level ozone, and more frequent wildfires release harmful smoke and particulates into the air. These changes, combined with ongoing pollution from sources like vehicle exhaust and industrial emissions, lead to longer and more intense episodes of unhealthy air.

A new study led by researchers from the University of Toronto in Canada examined more than 600 people and found that long-term exposure to air pollution is associated with early signs of heart damage. The research, which was recently published in the journal Radiology, indicates that fine particulate matter in the air may contribute to diffuse myocardial fibrosis, a form of scarring in the heart muscle that can precede heart failure.

Cardiovascular disease is the leading cause of death worldwide.

Long-term exposure to common air pollutants is also linked to a significantly higher risk of dementia. A separate study by researchers from the University of Cambridge in the UK analyzed data from nearly 30 million people and found that for every 10 micrograms of fine particulate matter per cubic meter of air, the risk of dementia increases by 17%. The study, which was recently published in The Lancet Planetary Health, found that exposure to nitrogen dioxide and soot was also strongly associated with an increased risk of dementia.

Dementia is estimated to affect more than 57 million people worldwide, a number that is expected to swell to 152 million by 2050.

Strengthening efforts to reduce air pollution could make a real difference for the environment and human health.

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Even low levels of air pollution may quietly scar your heart, MRI study finds

Is the air you breathe silently fueling dementia? A 29-million-person study says yes

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Earth Wise is a production of WAMC Northeast Public Radio

Indoor air and outdoor pollution

July 11, 2025 By EarthWise Leave a Comment

The majority of us spend about 80% of our time indoors. The quality of the air that we breathe depends on the age and type of building we occupy along with any sources of indoor pollution that may exist and, ultimately, the quality of the air outdoors. The HVAC used to heat, ventilate, and cool the building plays an important role.

The College of Engineering at the University of Utah used its Salt Lake City campus as a living laboratory to explore how outdoor air pollution affects indoor air quality. Specifically, the nature of outdoor pollution sources strongly affected how effectively HVAC systems prevented external sources from getting into buildings.

Of particular concern is fine particulate matter with a diameter of less than 2.5 microns. These PM 2.5 particles can penetrate deeply into lungs, potentially causing health problems like respiratory irritation and heart disease.

There are multiple sources of PM 2.5. The Utah study found that wildfire smoke had four to five times more PM 2.5 infiltration into buildings than pollution from inversions and wind-driven dust events.

An additional finding was that commercial HVAC systems that use air-side economizers are much less effective at keeping out particulate matter. These systems use special duct and damper systems that reduce energy use by drawing air from outdoors when temperature and humidity levels are optimum.

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Does outdoor air pollution affect indoor air quality?

Photo, posted June 15, 2024, courtesy of Peter Burka via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Solutions for cleaner air

July 4, 2025 By EarthWise Leave a Comment

Air pollution is a problem for most of the world’s cities. Many cities in India and China continue to face major public health crises due to their polluted air. American cities also don’t escape from polluted air. Californian cities still struggle with smog despite decades of effort to reduce it. But one major city that has waged a successful battle against air pollution is Paris, France.

Over the past 20 years, Paris has transformed its air by trading automobile roads for bike lanes, adding green spaces, and eliminating 50,000 parking spaces.

According to independent air quality tracking, levels of fine particulate matter in Paris have decreased 55% since 2005 and nitrogen dioxide levels have fallen 50%. A combination of regulations and public policies including steps to limit traffic and ban the most polluting vehicles have produced these results.

Despite pushback from various sources such as car owners’ associations, suburban commuters, and right-leaning politicians, Parisians have continued to pursue cleaner air policies. In April, Parisians voted to turn an additional 500 streets over to pedestrians. Last year, Paris sharply increased parking fees for SUVs, forcing drivers to pay three times more than they would for smaller cars.

Ambitious policymaking can directly improve health in large cities. As one former advisor to the city explains, the French capital has developed “an urban policy based on well-being.”

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Paris said au revoir to cars. Air pollution maps reveal a dramatic change.

Photo, posted June 3, 2018, courtesy of Francisco Anzola via Flickr.

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Benefits of electric school buses

July 1, 2024 By EarthWise Leave a Comment

There are about half a million school buses in use in the U.S. A large number of them are older, highly polluting diesel buses. There are well-established health and climate benefits of switching from diesel vehicles to electric vehicles but making the switch is expensive. Diesel buses generally cost between $65,000 to $120,000, depending on the type and configuration. Electric buses cost about $250,000 each.

The substantial cost makes it a difficult decision for local, state, and federal officials, particularly since the actual magnitude of the benefits is not well known.

A new study by researchers at Harvard’s T.H. Chan School of Public Health has quantified these benefits. According to the study, replacing each bus may yield up to $247,600 in climate and health benefits. These benefits derive from fewer greenhouse gas emissions and from reduced rates of adult mortality and childhood asthma.

The study compared the amounts of carbon dioxide emitted from diesel bus tailpipes to the emissions associated with generating electricity for the buses and producing their batteries. It also compared how these respective emissions contribute to fine particulate air pollution, which is linked to adult mortality and the onset of childhood asthma. The study concluded that particularly in dense urban settings, the savings incurred from electrifying older school buses easily outweigh the costs of replacing them.

An important question not tackled in the study is how electric school buses impact children’s exposure to in-cabin air pollution while riding the bus. This issue could further inform policy decisions.

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Electric school buses may yield significant health and climate benefits, cost savings

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Earth Wise is a production of WAMC Northeast Public Radio

Air pollution in India

February 19, 2024 By EarthWise Leave a Comment

India is one of the world’s most polluted countries. In fact, of the 30 cities with the worst air pollution around the globe, 21 of them can be found in India.

India’s capital city, New Delhi, is the most polluted city in the world. Concentrations of fine particulate matter (known as PM2.5) in Delhi, which is the name of the larger city that includes the capital New Delhi, are nearly 10 times greater than the World Health Organization guidelines.

To reduce air pollution in Delhi, officials have focused on measures within the city limits, including boosting public transportation and regulating pollution from industry.

But according to a review carried out by the University of Surrey and regional government officials in Delhi, the city will also need the help of its neighbors to tackle its killer smog problem. Some of the pollution plaguing Delhi comes from rural areas in the region – from things like crop burning, wood stoves, and power plants. The review, which was part of a paper recently published in the journal Sustainable Horizons, also recommends drafting regional air quality plans, producing smog forecasts, and creating airshed councils to help improve coordination.

Exposure to air pollution can cause all sorts of major health problems, including asthma, respiratory inflammation, as well as jeopardize lung function, and even promote cancer. Long-term exposure to PM2.5 is linked to premature death. In fact, air pollution causes an estimated 670,000 deaths every year in India.

Since air pollution doesn’t respect boundaries or borders, solutions require collaboration and the need to focus efforts more broadly in order to achieve emissions reduction goals.

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Delhi smog: India’s cities must look beyond their limits to clean up air pollution

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Increasing Air Pollution | Earth Wise

July 27, 2020 By EarthWise Leave a Comment

According to researchers from the University of Exeter, half of the world’s population is exposed to increasing air pollution despite global efforts to improve air quality. The study, which was completed in conjunction with the World Health Organization, suggests that air pollution represents a major and growing threat to human health.

For the study, which was recently published in the journal Climate and Atmospheric Science, the researchers reviewed global air quality trends between 2010 and 2016. The research team examined those findings against a backdrop of global policies to reduce air pollution. The researchers used ground monitoring data and satellite data to develop yearly air quality profiles for individual countries and regions.

The scientists focused on fine particulate matter, which is a mixture of solid particles and liquid droplets found in the air. Some of the particles, like dust, soot, or smoke, are large enough to be seen by the naked eye. Others are so small that they can only be seen using a microscope. Inhaling fine particulate matter can cause all sorts of health issues, including asthma, respiratory inflammation, and even promote cancer.

For much of the world’s population, the consequences of polluted air are more deadly than war, violence, and many diseases. According to the World Health Organization, more than four million deaths every year can be attributed to outdoor air pollution. Some of the major sources of air pollution include coal-fired power plants, agriculture, transportation, and deforestation.

The study found that low and middle income countries experience the highest burden of air pollution around the world, with the largest concentrations found in central and southeastern Asia.

More long term policies are needed to curb this growing threat to public health.

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Half of the world’s population exposed to increasing air pollution

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Earth Wise is a production of WAMC Northeast Public Radio.

The Cost Of Air Pollution | Earth Wise

March 12, 2020 By EarthWise Leave a Comment

The environmental consequences of burning fossil fuels are a dominant topic. The increasing changes in the climate have far-reaching effects across the globe and are a growing geopolitical crisis. But the climate effects of fossil fuel emissions are by no means the only problem they cause.

A new report by the Center for Research on Energy and Clear Air has, for the first time, attempted to quantify the global economic and health impacts of fossil fuel-caused air pollution. In total, the estimate is that the economic and health costs of air pollution from burning fossil fuels totaled $2.9 trillion in 2018, calculated in the form of work absences, years of life lost, and premature deaths. The cost represents 3.3 percent of global GDP, or about $8 billion per day.

The study focused on the health impacts of three specific types of pollutants: nitrogen dioxide, ozone, and fine particulate matter, which has the greater impact. Collectively, these pollutants cause about 1.8 billion days of missed work due to disease and $2.2 trillion in air pollution costs every year. Together, air pollution from these three pollutants is responsible for 4.5 million premature deaths around the world each year.

According to the report, the most premature deaths from fossil fuel-related air pollution in 2018 were in mainland China (1.8 million), India (1 million), and the United States (230,000). As a result, those three countries also faced the highest annual costs: $900 billion in China, $600 billion in the U.S., and $150 billion in India.

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Toxic Air: The Price of Fossil Fuels (Full Report)

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Air Pollution And Bone Health | Earth Wise

February 5, 2020 By EarthWise Leave a Comment

Many of the negative effects of air pollution are well documented. Studies have shown that exposure to air pollution is associated with an increased risk of lung cancer, stroke, respiratory and cardiovascular diseases, and so on.

Now, according to a new study in India led by the Barcelona Institute for Global Health (ISGlobal), exposure to air pollution is also associated with a higher risk of developing osteoporosis. Osteoporosis, which literally means porous bone, is a disease in which the density and quality of bone is reduced. As bones become more porous and fragile, the risk of fracture is greatly increased.

The study, which surveyed 3,700 people from 28 villages in southern India, was recently published in the medical journal Jama Network Open.

The researchers used a model to estimate air pollution by fine particulate matter (commonly referred to as PM2.5) and black carbon at each participant’s residence. The research team then assessed bone health using a special type of radiography (called dual-energy x-ray absorptiometry) that measures bone density. They measured bone mass of the participants’ left hip and at the lumbar spine.

The results showed that exposure to air pollution, particularly fine particulate matter, was associated with lower levels of bone mass. Annual average exposure to PM2.5 was 32.8 micrograms per cubic meter, well above the maximum levels recommended by the World Health Organization (10 micrograms per cubic meter) and the U.S. EPA (12 micrograms per cubic meter).

The researchers say their findings add to a growing body of evidence that indicates that particulate air pollution is relevant for bone health.

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Air pollution can worsen bone health

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Dangerous Smoke From Australia’s Wildfires | Earth Wise

January 13, 2020 By EarthWise Leave a Comment

Wildfires raging across Australia have devastated large swathes of land and prompted one of the largest evacuations in the country’s history. The fires, which have scorched approximately 20 million acres, have also killed 27 people and affected an estimated one billion animals at the time of this recording. The fire season, though still young, already ranks as among the worst in Australia’s recorded history.

Away from the flames, millions more in Australia are breathing unhealthy air as a result of the smoke from these wildfires. Wildfires release all sorts of dangerous air pollutants, like carbon monoxide and nitrous oxide. But wildfires also release fine particulate matter (more commonly referred to as PM2.5), which can be transported long distances. Breathing in these microscopic particles can lead to respiratory and cardiovascular problems. High levels of PM2.5 are particularly harmful to older people, young children, and those with weakened immune systems.

The Australian capital city of Canberra has been covered in a thick haze of smoke from nearby wildfires. Canberra recorded its worst air quality day on January 2nd, when levels of PM2.5 spiked to more than 200 micrograms per cubic meter during the worst hour.

Smoke has also been fouling Sydney’s air off and on for months, with PM2.5 readings hitting nearly 400 micrograms per cubic meter last month during the highest hour of pollution.

The U.S. EPA has in place an annual PM2.5 standard of 12 micrograms per cubic meter and a daily (or 24 hour) standard of 35.

According to the IPCC, southern Australia is expected to see increased risk of fire as the planet continues to warm. Regrettably, this could be the new normal.

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Millions of Australians Are Choking on Smoke From Wildfires

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Air Quality In The U.S.

November 13, 2019 By EarthWise Leave a Comment

Globally, poor air is a serious problem. According to the World Health Organization, exposure to air pollution is linked to the premature deaths of an estimated 7 million people every year. In fact, 91% of the people on the planet live in places where air pollution exceeds WHO guideline limits.

In the United States, air pollution has dramatically improved over the last four decades due in large part to federal regulations put in place under the Clean Air Act of 1970. Fine particulate matter (known as PM2.5) and other pollution, including ozone, sulphur dioxide, and nitrogen dioxide, have all decreased during this time span.

But according to recent research, this trend has unfortunately done an about-face. New data reveals that air pollution has increased nationally since 2016. An analysis of Environmental Protection Agency data by researchers at Carnegie Mellon University found that, on average, fine particulate pollution increased 5.5% across the country between 2016 and 2018.

This increase in fine particulate pollution was associated with nearly 10,000 additional premature deaths in the United States during that time period.

According to researchers, there are several factors likely causing this uptick in unhealthy air, including increases in both driving and the burning of natural gas. Wildfires out west are also thought to be a major contributor.

The researchers also suggest that a decrease in enforcement of the Clean Air Act may also be playing a role. The law put in place strict air pollution standards for vehicles, factories, power plants, and other sources, and is credited with saving hundreds of thousands of lives.

It’s time for clean air to be recognized as a basic human right.

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America’s Air Quality Worsens, Ending Years of Gains, Study Says

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Cleaner Air Saves Lives

September 25, 2019 By EarthWise Leave a Comment

A new study by Columbia University has concluded that lower air pollution levels saved an estimated 5,660 lives in New York State in 2012, compared to 2002 mortality levels.

The study looked at New York State levels of the specific type of pollution known as fine particulate matter, referred to as PM2.5. These microscopic particulates are a mixture of solid particles and liquid droplets that either come from burning fuel or are formed in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides from power plants, industries, and automobiles.

Long-term exposure to PM2.5 can lead to respiratory and cardiovascular problems.

The study looked at extensive amounts of data to analyze trends in PM2.5 levels across New York State. The data showed that PM2.5 levels dropped by 28 to 37% between 2002 and 2012. This was a result of continued progress in cleaner vehicles, the reduction of high sulfur-dioxide emitting coal-burning power plants, and other air pollution reduction programs. They calculated that this amount of reduction in PM2.5 reduced the air pollution mortality burden for New York State residents by 67% – from 8,410 premature deaths in 2002 to 2,750 deaths in 2012.

The study provides evidence that emission controls on air pollutants – which were initiated by the Clean Air Act of 1970 and later expanded in 1990 – have improved public health across New York State. According to the researchers, the study is a key step to documenting the health benefits from cleaner air.

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