Health Impact of Air Pollution

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Years of scientific research have clearly established that particle pollution and ozone are a threat to human health at every stage of life, increasing the risk of premature birth, causing or worsening lung and heart disease, and shortening lives. Some groups of people are more at risk of illness and death than others, because they are more likely to be exposed, are more vulnerable to health harms, or often both.

Air pollution can harm children and adults in many ways

Respiratory

Wheezing and coughing

Shortness of breath

Asthma attacks

Worsening COPD

Lung cancer

Air pollution health impacts illustration

Other

Premature death

Susceptibility to infections

Heart attacks and strokes

Impaired cognitive functioning

Metabolic disorders

Preterm births and low birth weight

Health Effects of Particle Pollution

Particle pollution – also known as particulate matter or soot – is a deadly and growing threat to public health in communities around the country. The more researchers learn about the health effects of particle pollution, the more dangerous it is recognized to be. 

Particle pollution refers to a mixture of tiny bits of solids and liquids in the air we breathe. Particulate matter (PM) comes from many sources. Power plants, diesel- and gasoline-powered vehicles and equipment, and factories either directly emitting fine particles or generating pollutant gases, such as nitrogen oxides (NOx) and sulfur oxides (SOx), which are known as PM precursors because they can form into fine particles in the atmosphere. Other sources of particle pollution include agriculture, construction, wildfires, burning wood in wood stoves or residential fireplaces and burning biomass for electricity.

Researchers and regulators categorize particles according to their physical size, grouping them as coarse, fine and ultrafine. Coarse particles, called PM10-2.5, can include wind-blown dust, ash, pollen and smoke. Fine particles, PM2.5, are most often a by-product of burning wood or fossil fuels and may include toxic compounds, salts and metals. The tiniest are ultrafine particles, or PM0.1, which are included in the larger category of PM2.5 and are also produced by combustion.

Individual fine particles are too small to be visible, but when pollution levels are high, they can make the air appear thick and hazy.

Sources of particle pollution include motor vehicles, factories, power plants, equipment, wood burning and wildfires.


The differences in size make a difference in how particles affect our health. Our bodies’ natural defenses help us keep the coarse particles we inhale out of the deepest parts of our lungs, although these particles do deposit in the larger airways. However, those defenses do not keep the smaller fine or ultrafine particles from penetrating deep into the lungs and even all the way into the air sacs. Many of these particles get trapped there, while the smallest are so tiny that they can pass through the air sacs into the bloodstream and disperse to other organs of the body. 

  • Fine particle pollution can be very dangerous to breathe and can trigger illness, hospitalization and premature death. Exposure to fine particles can cause cardiovascular diseases such as strokes and heart attacks. It also can cause respiratory harm including decreased lung function, asthma exacerbation, worsening chronic obstructive pulmonary disease (COPD), and increased hospital admissions and emergency department visits for these conditions. 1, 2 Fine particle pollution can contribute to diabetes, nervous system disorders and lung cancer.

Researchers estimate that PM2.5 is responsible for more than 50,000 premature deaths in the United States every year. 3 There is no safe threshold of PM2.5 exposure, since health impacts are observed even at very low concentrations, including below current standards. 4

Short-term (hours to a few days) exposure to PM2.5 is linked to significant increases in:

  • All-cause, respiratory and cardiovascular mortality 

Even short spikes in PM2.5 levels were strongly associated with increases in mortality. A multi-country study found that a 10 microgram per cubic meter (µg/m³) spike in daily PM2.5 was associated with increases in daily all-cause mortality in all four countries studied, including the United States. Robust effects were directly observed on the same day and the following day, at relatively low ambient pollutant levels. 5 A pooled multicity study in Belgium found that each 10 µg/m³ PM2.5 increment caused a 0.6% increase in same-day natural‑cause mortality and significant increases in cardiovascular and respiratory mortality tied to same-day PM2.5 levels. 6 An analysis of mortality data from 380 cities across 24 countries and multiple seasons over a 22-year period found persistent short-term PM2.5 effects on cardiovascular and respiratory mortality. 7 A global mortality assessment of more than 13,000 cities found that short-term PM2.5 exposure causes over 1 million premature deaths each year worldwide. 8

  • Hospitalizations & emergency department visits from all-cause, cardiovascular, and respiratory illnesses

A recent national study of 50.1 million insured adults across 2,939 U.S. counties reported that 10 µg/m³ increments over ambient daily PM2.5 level of 15 µg/m³ (which is the 2021 World Health Organization [WHO]’s 24 hour PM2.5 guideline) were associated with a significant number of emergency department visits and hospital admissions related to respiratory illnesses (asthma/COPD exacerbations, influenza/pneumonia and upper/lower infections), cardiovascular illnesses (heart disease, rheumatic fever, hypertension and cerebrovascular diseases), and natural causes, with stronger effects in adults over 65 years. 9, 10

  • Out-of-hospital cardiac arrest 

In a nationwide study in Japan, each 10 µg/m³ increase over average daily PM2.5 of 11.98 µg/m³ was associated with higher odds of all-cause and cardiac-origin out-of‑hospital cardiac arrests, with older adults being more susceptible. 11

Long-term (months to years) chronic exposure to PM2.5 is linked to significant increases in:

  • All-cause mortality and mortality from cardiovascular diseases, respiratory diseases and lung cancer 

A recent meta-analysis of 106 large cohort global studies concluded with high certainty that long term chronic exposure to PM2.5 significantly increases all-cause mortality, raises mortality from cardiovascular disease and from respiratory diseases, and from lung cancer. 12 Three large-scale studies conducted by the Health Effects Institute in the U.S., 13 Canada (MAPLE study) 14 and Europe (ELAPSE study) 15 showed strong positive associations between all-cause, cardiovascular and respiratory mortality and chronic long-term exposure to PM2.5 at levels below 12 µg/m³ (the previous U.S. National Ambient Air Quality Standards (NAAQS) and the European Union Air Quality Standards). The studies found that even very small increases in PM2.5 increased the risk of death, with no safe level identified. The MAPLE study found mortality associations to persist down to approximately 2.5 µg/m³. 16, 17

Previous studies, including one on a cohort of more than one million adults in the U.S., showed that long-term exposure to PM2.5 was associated with elevated risk of early death. The increased risk was primarily associated with death from cardiovascular and respiratory causes, including heart disease, stroke, influenza and pneumonia. Researchers also found a similar association between exposure to fine particle pollution and an increased risk of death from lung cancer among people with no smoking history. 18, 19

  • Cardiovascular events

A diverse cohort study of 3.7 million adults in Northern California found long-term exposure to PM2.5 at concentrations (below 12 µg/m³) is associated with an increased risk of various cardiovascular illnesses, including incident acute myocardial infarction, ischemic heart disease mortality and cardiovascular disease mortality. 20

  • Neurological disease

A new large cohort study of 27.8 million Medicare recipients aged 65 and older across the U.S. provides compelling evidence for the increased risk of Alzheimer’s disease from long-term exposure to PM2.5 among older adults. A five-year average PM2.5 exposure was associated with an increased risk of Alzheimer’s disease incidence, with individuals who had experienced a stroke being more vulnerable and at higher risk. 21

Research has also linked year-round exposure to particle pollution to a wide array of serious health effects at every stage of life, from conception through old age. Among individuals who are pregnant, and for fetuses and children, long-term particle pollution exposure is linked to:

  • Increased risk of preterm birth and low birth weight; 22
  • Increased fetal and infant mortality; 23
  • Impaired neurological development and cognition; 24
  • Reduced lung development and impaired lung function in children; 25
  • Higher likelihood of children developing asthma. 26

Across numerous seminal studies that looked at different groups of people living in different parts of the country, the results consistently showed a clear relationship between long-term exposure to particulate matter and mortality. 27 In adults, long-term particle pollution exposure is linked to:

  • Increased risk from existing cardiovascular and respiratory disease, including a worsening of heart disease, atherosclerosis and COPD; 28, 29
  • Higher likelihood of developing diabetes and subsequent complications; 30, 31
  • Higher likelihood of getting lung cancer and of dying from it; 32
  • Impaired cognitive functioning and an increased risk of Parkinson’s disease, Alzheimer’s disease and other dementias later in life; 33, 34
  • Increased risk of clinical depression and anxiety. 35

The good news is that cleaning up particle pollution makes a difference. Research has shown a consistent relationship between decreasing PM2.5 concentrations and improving respiratory health in children and reduced mortality of adults in communities that have lowered their levels of year-round particle pollution. 36, 37

Anyone who lives where particle pollution levels are high is at risk. Some people face greater risk, however, based on their underlying health and other characteristics. Research has shown that the groups at the greatest risk from particle pollution include:

  • Women who are pregnant and fetuses;38
  • Infants, children and people age 65 and older;39
  • People with lung disease, especially asthma, but also people with COPD;40
  • People with cardiovascular disease;41
  • People with lung cancer;42
  • People of color;43
  • Current or former smokers;44
  • People with low incomes;45 and
  • People who are obese or have diabetes.46

Health Effects of Ozone Pollution

Ground-level ozone, sometimes known as smog, is one of the most widespread and dangerous pollutants in the United States. Scientists have studied the effects of ozone on human health for decades. Hundreds of studies have confirmed that ozone harms people at levels currently found in many parts of the United States. 

Ozone is a gas composed of molecules with three oxygen atoms. (The oxygen we need for life is made up of molecules with two oxygen atoms.) Ozone forms in the lower atmosphere when a combination of pollutants - nitrogen oxides (NOx) and volatile organic compounds (VOCs) - “cook” together in sunlight through a series of chemical reactions. NOx and VOCs are produced primarily from burning fossil fuels such as coal, methane gas, oil, gasoline or diesel in power plants, motor vehicles and other sources of combustion. VOCs are also released from vaporizing solvents and other chemicals from oil and gas operations, chemical plants, refineries, factories, gas stations, paint, consumer products and other sources. 

If these ingredients are present under the right conditions, they react to form ozone. Sunlight is key, with higher temperatures speeding up ozone production. Because the reactions take place in the atmosphere, ozone often shows up downwind of the sources of the original emissions, sometimes many miles from where it formed.

Ozone air pollution is sometimes called ground-level ozone, to distinguish it from the much higher-altitude stratospheric ozone layer that protects people from damaging ultraviolet rays from the sun.

Ozone gas is a powerful lung irritant and causes severe harm to the respiratory system. When inhaled into the lungs, ozone reacts with the delicate lining of the small airways, causing inflammation and other damage that can impact multiple body systems. Breathing problems such as chest tightness, coughing and shortness of breath can occur within hours of exposure. Even healthy young adults may experience respiratory symptoms and decreased lung function.47 Exposure to ozone can be deadly and there is no known safe level of ozone exposure.48

Short-term (hours to few days) exposure to ozone is associated with:

  • Worsening of asthma and COPD symptoms leading to increased medication use, increases in emergency department visits and hospital admissions even at current ambient levels of ozone.49,50
  • Susceptibility to respiratory infections such as pneumonia, resulting in an increased likelihood of emergency department visits and hospitalizations.51
  • Decreased lung function characterized by a temporary drop in how much air the lungs can blow out quickly, airway inflammation and cough/chest tightness; effects can stack up over consecutive high-ozone days.52
  • Increased risk of premature death.53,54

Long-term (months to years) chronic exposure to ozone is associated with:

  • Damage to the airways, leading to development of COPD;55
  • Development of new cases of asthma in children,56 with early-life chronic exposure impacting later disease;57
  • Persistent airway inflammation through adolescence - this effect is seen even among healthy adolescents;58,59
  • Increased allergic response;60
  • Increased risk of respiratory mortality from annual ozone exposure was found in an updated WHO meta-analysis of 26 cohort studies;61
  • Increased risk of death due to cardiovascular disease.62 Even a small increase in ozone levels was linked to a much higher risk of dying from heart disease in a very large study of adults in China.63 Other global research also shows that people living in rural areas often breathe more ozone pollution over the long term than people in nearby cities, which may put them at greater risk for heart-related health problems;64
  • All-cause mortality: A recent study found that the number of deaths caused by long‑term ozone exposure is much higher than previously thought, with the western U.S. among the areas seeing significant ozone‑related deaths around the world.65

The inflammation and oxidative stress caused by exposure to ozone may also cause or worsen other disease conditions over time. Some potential risks include:

  • Increased risk of metabolic disorders such as glucose intolerance, hyperglycemia and diabetes;66
  • Impact on the central nervous system, including brain inflammation, structural changes and increased risk of cognitive decline;67,68
  • Increased likelihood of reproductive and developmental harm, including reduced fertility, pregnancy complications, preterm birth, stillbirth and low birth weight;69,70
  • Cardiovascular effects.71

Anyone who spends time outdoors where ozone pollution levels are high may be at risk. Some people face a higher-than-average risk, however, because of their underlying health and other characteristics. Research has shown that the groups at greatest risk from ozone pollution include:

  • Women who are pregnant and fetuses;72
  • Infants, children and teens;
  • Anyone 65 and older;
  • People with existing lung disease such as asthma and COPD;
  • People who work or exercise outdoors.73

Ambient air contains multiple pollutants, including ozone and PM2.5. These pollutants do not exist in isolation nor are they inhaled individually. Short-term and/or long-term exposures to air pollutants cause, or are associated with, similar and often overlapping adverse health endpoints. Additionally, climate change imposes a penalty on these conventional pollutants by increasing their concentrations and/or exacerbating their health impacts. Other factors, including sociodemographic (e.g., age, life stages, race/ethnicity, existing morbidities) and socioeconomic (e.g., education level, income, profession, location) elements impose additional vulnerabilities on populations, increasing the risk of health harms from pollutant exposures.74 PM2.5 and ozone co-exposure contribute to cumulative health burdens, more than individual short-term exposures. Several recent multi-city global studies showed that co-exposures to PM2.5 and ozone exacerbate their single-pollutant health risk on total, cardiovascular, and respiratory mortality and morbidity burden.75,76,77 The health risks and impacts of single pollutant exposures are likely an underestimation if the cumulative health burden of co-exposures to multiple pollutants and their interactions are not taken into account.

People at Risk

The health burden of air pollution is not evenly shared. While everyone’s health is harmed by breathing air pollution, some people are more at risk of illness and death than others. Several key factors affect an individual’s level of risk:

  • Exposure – Where someone lives, where they go to school and where they work makes a big difference in how much air pollution they breathe. In general, the higher the exposure, the greater the risk of harm.
  • Susceptibility – Women who are pregnant and their fetuses, children, older adults and people living with chronic conditions, especially heart and lung disease, may be physically more susceptible to the health impacts of air pollution than other adults.
  • Access to healthcare – Whether or not a person has health coverage, a healthcare provider, and access to linguistically and culturally appropriate health information may influence their overall health status and how they are impacted by environmental stressors like air pollution.
  • Psychosocial stress – There is increasing evidence that non-physical stressors such as poverty, racial/ethnic discrimination and residency status can amplify the harmful effects of air pollution.

These risk factors are not mutually exclusive and often interact in ways that lead to significant health inequities among subgroups of the population. Taken all together, these high-risk categories account for a large proportion of the U.S. population.

People under the age of 18 are more susceptible to air pollution than adults because they experience higher biological exposure and can accumulate lifelong harm from early exposure to pollutants. Children face greater physiological vulnerability because they breathe in more air and consequently higher doses of air pollutants per kilogram of body weight than adults for the same ambient exposure. Even “low” pollution days can deliver adult-equivalent high doses of air pollutants to children.78 They are often more likely to spend time outdoors, running around, being active and breathing hard. Consequently, they are more exposed to polluted outdoor air than adults typically are.

Because children’s lungs, which start growing in utero and continue into early adulthood, are still developing alveoli, airways, and immune defenses, air pollution causes them greater structural and functional harm in ways that do not occur in adults. The developing brain and heart may also be affected, with life-long consequences.79 Prenatal exposure to air pollutants may also contribute to poor respiratory health in later life.80,81

Kids are more vulnerable to air pollution because:

  • Their lungs are still developing
  • They breathe more air for their body size
  • They often spend more time outdoors

The connection between air pollution exposure in childhood and chronic disease:

A recent review of scientific literature on air pollution-related health impacts on children confirmed that air pollutants, including particulate matter and ozone, significantly increase the risk of respiratory diseases. Both short-term and long-term postnatal exposures can cause severe and recurrent upper and lower respiratory infections and middle ear inflammation or infection, leading to frequent hospitalizations and reduced quality of life. Promotion of oxidative stress, induction of inflammatory responses, dysregulation of the still-developing immune system, and epigenetic modifications are among potential mechanisms implicated in the development of pollution-associated respiratory tract diseases in pediatric populations.82

Air pollution in childhood can cause long-term harm, including:

  • Impeding lung growth
  • Contributing to new asthma cases
  • Increasing risk of respiratory diseases

A 2024 study of U.S. children found that early life exposure to PM2.5 significantly increased asthma incidence in early and mid-childhood, with those living in urban communities characterized by fewer resources and experiencing cumulative environmental exposures facing higher risk.83 Two recent large cohort studies of children from Asia confirmed that long-term PM2.5 exposure significantly increases the risk of asthma symptoms, impedes lung growth,84 and increased risk of pediatric respiratory hospitalizations.85

Another recent study from six U.S. cities found that early-life exposure to low ambient ozone in the first two years of life exacerbated asthma by 31% and wheeze by 30% at ages 4–6.86

Pollution activates unique airway gene networks in children. A 2025 investigation found that PM2.5 and ozone activate distinct airway-related molecular networks in children with asthma compared to healthy children. In children with asthma, pollutants triggered inflammatory and airway remodeling pathways as part of adaptive immune responses, while the molecular responses in the latter centered on DNA repair. This study provides insights into the disproportionate burden of air pollution on children with asthma.87

Air pollution disproportionately harms children in disadvantaged communities. A 2025 children’s environmental health analysis88 found that EPA’s rulemaking in reducing air pollution, particularly in setting PM2.5 standards, has historically undervalued children’s risks, with no accounting of potential risk of adverse health impacts on children living in disadvantaged communities.89 The study argues for strengthening the “vulnerable groups” definition and a more stringent application of the “margin of safety” in setting NAAQS for PM2.5, ozone and the other criteria pollutants to better protect children, including those living in disadvantaged communities, due to the significant impacts of air pollution on their lifelong health.

Much of the illness and premature death caused by air pollution occurs in older adults, who are at increased risk of harm for several reasons. As a person ages, the normal process of thinning and weakening of the lung tissue and the supporting muscle and bones of the ribcage results in diminishing lung function over time. The impairment that results from exposure to air pollutants then has an add-on effect, putting stress on the lungs and heart. Older people are also more likely to be living with chronic diseases, and there is evidence that co-existing chronic lung, heart or circulatory conditions may worsen following exposure to environmental pollutants.90

The strength of the immune system also declines with age, leaving older people at greater risk of contracting infections and less able to get them under control before they become serious. Because exposure to air pollution increases susceptibility to respiratory infections, it also increases the risk of severe illness and death in older adults.

For the millions of people in the U.S. living with illnesses such as asthma, COPD, diabetes, heart disease and lung cancer, exposure to air pollution places them at greater risk of harm to their health than those without disease. The cellular injury and systemic inflammation triggered by breathing ozone and particle pollution put additional stress on people’s lungs, heart and other organs already compromised by disease. This can result in a worsening of symptoms, increased medication use, more frequent emergency department visits and hospitalizations, an overall reduced quality of life and—far too often—premature death in older people.

Pregnancy is always a susceptible time for both the person who is pregnant and the developing fetus. The pregnant body undergoes dramatic physiological changes in hormone levels, metabolism and circulation throughout the months of gestation. The rapid and complex development of the fetus is a precisely timed and sequenced process, and is subject to disruption by external agents. The inflammation and oxidative stress resulting from exposure to air pollution during pregnancy can increase the risk of hypertensive disorders, including preeclampsia, and lead to intrauterine inflammation and damage to the placenta that can disrupt the growth and development of the fetus. Fetal health may also be impacted by environmental contaminants that have been shown to cross the placenta.91

Exposure to both ozone and particle pollution during pregnancy is associated with premature birth, low birth weight and stillbirth. These risks are amplified when the woman who is pregnant is also at higher risk of health harm from air pollution in other ways, such as experiencing poverty or having asthma.92

Research has shown that people of color are more likely to be exposed to air pollution and more likely to suffer harm to their health from air pollution than white people.93, 94 Much of this inequity can be traced to the long history of systemic racism in the United States. Practices such as redlining, the discriminatory outlining of so-called “riskier” neighborhoods by mortgage lenders, institutionalized residential segregation in the 20th century, impairing the ability of many people of color to build wealth and limiting their mobility and political power. Over the years, decision-makers have found it easier to place sources of pollution such as power plants, industrial facilities, landfills and highways, in or near economically disadvantaged communities of color than in more affluent, predominantly white neighborhoods. The resulting disproportionate exposure to air pollution has contributed to high rates of emergency department visits for asthma and other diseases.95, 96

People of color are also more likely than white people to be living with one or more chronic conditions that make them more susceptible to the health impacts of air pollution, including asthma and diabetes.97 Psychosocial stress from racial/ethnic discrimination has been shown to increase the harmful effects of exposure to air pollution.98

There is evidence that having low income or living in lower income areas puts people at increased risk from air pollution, although the correlation is not as strong as with race and ethnicity.99, 100 People living in poverty are more likely to live in close proximity to sources of pollution and have fewer resources to relocate than people with more financial security.101 Poverty itself, along with the problems that beset many low-income communities, such as lack of safety, green space, and high-quality food access, have been associated with increased psychosocial distress and chronic stress, which in turn make people more vulnerable to pollution-related health effects.102 People with low income also have lower rates of health coverage and less access to quality and affordable health care to provide relief to them when they get sick.

There is some evidence suggesting that smoking modifies the effects of PM2.5 exposures and that people who smoke or used to smoke are at greater risk of health harm from exposure to fine particle pollution compared with never-smokers. They are more likely to develop lung cancer and to die prematurely due to this exposure.103 Smoking damages the lungs, heart, blood vessels and other organs.104 This impairment leaves the person with a smoking history more vulnerable to the health impact of air pollution than someone with no smoking history.

Did You Know?

  1. 33.5 million children (46% of all kids) in the U.S. live in an area that received a failing grade for at least one measure of air pollution.
  2. More than 7 million children in the United States (10% of all kids) live in a community with failing grades for all three measures.
  3. More than four in 10 (44%) people of all ages in the U.S. live where the air they breathe earned an F in “State of the Air” 2025.
  4. Nearly 33 million people live in counties that got an F for all three air pollution measures in “State of the Air” 2025.
  5. Infants, children and teens as a group are more susceptible to the health impacts of air pollution. Their lungs are still developing, they breathe more air for their body size than adults, and they are frequently exposed to outdoor air.
  6. Breathing ozone irritates the lungs, resulting in inflammation—as if your lungs had a bad sunburn.
  7. Breathing in particle pollution can increase the risk of lung cancer.
  8. Particle pollution can cause early death and heart attacks, strokes and emergency room visits.
  9. Particles in air pollution can be smaller than 1/30th the diameter of a human hair. When you inhale them, they are small enough to get past the body's natural defenses.
  10. Ozone and particle pollution are both linked to increased risk of premature birth and lower birth weight in newborns.
  11. If you live or work near a busy highway, traffic pollution may put you at greater risk of health harm.
  12. People who work or exercise outside face increased risk from the effects of air pollution.
  13. Millions of people are especially vulnerable to the effects of air pollution, including children, older adults and people with lung diseases such as asthma and COPD.
  14. Research shows that people of color and people with lower incomes are disproportionately affected by air pollution that puts them at higher risk for illness.
  15. Air pollution is a serious health threat. It can trigger asthma attacks, harm lung development in children, and even be deadly.
  16. You can protect yourself by checking the air quality forecast in your community and avoiding exercising or working outdoors, if possible, when unhealthy air is expected.
  17. Climate change enhances conditions for ozone pollution to form and makes it harder to clean up communities where ozone levels are high.
  18. Climate change increases the risk of wildfires whose smoke spreads dangerous particle pollution.
  19. Policymakers at every level of government must take steps to clean the air their constituents breathe.
  20. The nation has the Clean Air Act to thank for decades of improvements in air quality. This landmark law has successfully driven pollution reduction for over 55 years.
  21. This U.S. Environmental Protection Agency (EPA) is rolling back clean air protections and has eliminated health costs from its economic analyses. Both actions threaten clean air progress.
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  1. U.S. EPA. Supplement to the 2019 Integrated Science Assessment (ISA) for Particulate Matter (PM) National Ambient Air Quality Standard (NAAQS). 2022; EPA/600/R-22/028; Table 2-1 - Causal and likely to be causal causality determinations for short- and long-term PM2.5 exposure.

  2. U.S. EPA. Integrated Science Assessment (ISA) for Particulate Matter National Ambient Air Quality Standard (NAAQS). 2019; EPA/600/R-19/188; Sections 9.1.2.6, 6.1.2, 5.1.2.1, 5.1.2.1.1

  3. Health Effects Institute (HEI), Institute for Health Metrics and Evaluation’s (IHME’s) Global Burden of Disease (GBD). State of Global Air 2024.

  4. Boogaard H, et al. Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: The HEI Experience and What's Next? Environ Sci Technol. 2024; 58(29):12767-12783.

  5. Ma Y, et al. Short-Term Exposure to Fine Particulate Matter and Nitrogen Dioxide and Mortality in 4 Countries. JAMA Netw Open. 2024;7(3):e2354607.

  6. Demoury C, et al. Impact of short-term exposure to air pollution on natural mortality and vulnerable populations: a multi-city case-crossover analysis in Belgium. Environ Health. 2024; 23, 11.

  7. Schwarz M, et al. Temporal variations in the short-term effects of ambient air pollution on cardiovascular and respiratory mortality: a pooled analysis of 380 urban areas over a 22-year period. The Lancet Planetary Health. 2024; 8(9), e657 - e665.

  8. Yu W, et al. Estimates of global mortality burden associated with short-term exposure to fine particulate matter (PM2·5). The Lancet Planetary Health. 2024; 8(3):e146 - e155

  9. Sun Y, et al. Short term exposure to low level ambient fine particulate matter and natural cause, cardiovascular, and respiratory morbidity among US adults with health insurance: case time series study. BMJ. 2024; 384:e076322.

  10. Wei Y, et al. Short term exposure to fine particulate matter and hospital admission risks and costs in the Medicare population: time stratified, case crossover study. BMJ, 2019; 367:l6258

  11. Zhao B, et al. Short term exposure to ambient fine particulate matter and out of hospital cardiac arrest: a nationwide case crossover study in Japan. The Lancet Planetary Health. 2020; 4(1):e15–e23

  12. Orellano P, Kasdagli MI, Pérez Velasco R, Samoli E. Long-Term Exposure to Particulate Matter and Mortality: An Update of the WHO Global Air Quality Guidelines Systematic Review and Meta-Analysis. Int J Public Health. 2024; 69:1607683

  13. Dominici F, et al. Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: Implementation of Causal Inference Methods. Res Rep Health Eff Inst. 2022; 211:1-56

  14. Brauer M, et al. Mortality-Air Pollution Associations in Low-Exposure Environments (MAPLE): Phase 1. Res Rep Health Eff Inst. 2019; 203:1-87

  15. Brunekreef B, et al. Mortality and Morbidity Effects of Long-Term Exposure to Low-Level PM2.5, BC, NO2, and O3: An Analysis of European Cohorts in the ELAPSE Project. Res Rep Health Eff Inst. 2021; (208):1-127

  16. Brauer M, et al. Mortality-Air Pollution Associations in Low-Exposure Environments (MAPLE): Phase 1. Res Rep Health Eff Inst. 2019; 203:1-87

  17. Boogaard H, et al. Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: The HEI Experience and What's Next? Environ Sci Technol. 2024; 58(29):12767-12783.

  18. Pope CA, et al. Mortality risk and fine particulate pollution in a large, representative cohort of U.S. Adults. Environ Health Perspect. 2019; 127(7):077007-1-077007-9.

  19. Wu X, Braun D, Schwartz J, Kioumourtzoglou MA, Dominici F. Evaluating the impact of long-term exposure to fine particulate matter on mortality among the elderly. Sci Adv. 2020; 6(29):eaba5692; Ibid 13.

  20. Alexeeff SE, et al. Association of Long-term Exposure to Particulate Air Pollution With Cardiovascular Events in California. JAMA Netw Open. 2023; 6(2):e230561.

  21. Deng Y, et al. The role of comorbidities in the associations between air pollution and Alzheimer’s disease: A national cohort study in the American Medicare population. PLOS Medicine. 2026.

  22. Bekkar B, Pacheco S, Basu R, DeNicola N. Association of air pollution and heat exposure with preterm birth, low birth weight and stillbirth in the U.S.: A systemic review. JAMA Network Open. 2020; 3(6):e208243.

  23. Bekkar B et al. JAMA Network Open. 2020; 3(6):e208243.

  24. Ni Y, et al. Associations of pre- and postnatal air pollution exposures with child behavioral problems and cognitive performance: A U.S. multi-cohort study. Environ Health Perspect. 2022; 130(6).

  25. U.S. EPA. ISA for PM NAAQS, 2019, Section 5.2.2.2.1.

  26. U.S. EPA. ISA for PM NAAQS, 2019, Section 5.2.3.1.

  27. U.S. EPA. ISA for PM NAAQS, 2019, Section 11.2.

  28. U.S. EPA. ISA for PM NAAQS, 2019, Section 6.2.2.

  29. U.S. EPA. ISA for PM NAAQS, 2019, Section 5.2.5.

  30. Liu F et al. Associations between long-term exposure to ambient air pollution and risk of type 2 diabetes mellitus: a systematic review and meta-analysis. Environ Pollut. 2019; 252(ptB):1235–1245.

  31. Wu Y, et al. Ambient air pollution associated with incidence and dynamic progression of type 2 diabetes: a trajectory analysis of a population‑based cohort. BMC Med. 2022; 20:375.

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