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Particulate Matter Effects on Health - Air (U.S. National Park Service)

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Exposure to air pollution can affect everyone's health. When we breathe in air pollutants, they can enter our bloodstream and contribute to coughing or itchy eyes and cause or worsen many breathing and lung diseases, leading to hospitalizations, cancer, or even premature death.

Minnesota's air currently meets all federal air quality standards. However, even levels of air pollution below the standards can affect people's health, including levels currently found in parts of Minnesota.

No matter where you live, you can be exposed to air pollution from vehicle exhaust, smoke, road dust, industrial emissions, pollen, gas-fueled yard equipment, chemicals we use in our homes, and other sources.

Both short-term and long-term exposure to air pollutants can cause a variety of health problems. For people with asthma or chronic obstructive pulmonary disease (COPD/emphysema or chronic bronchitis), air pollution can make it harder to breathe, trigger asthma attacks, or cause wheezing and coughing. Air pollution also increases the risk of respiratory infections, heart disease, stroke, and lung cancer, and more severely affects people who are already ill.

People's health risks from air pollution vary widely depending on age, location, underlying health, and other factors. Many studies show that low-income communities and minority populations are disproportionately exposed to air pollution and are more vulnerable to adverse health impacts. Data from the Minnesota Department of Health show disparities in heart and lung disease by age, race/ethnicity, income level, and geography. Minnesota also has significant disparities in asthma prevalence by race/ethnicity. The asthma hospitalization rate among Twin Cities children is more than 50% higher than among children living in Greater Minnesota.

Populations most at risk of health problems related to air pollution:

people with lung diseases, such as asthma, chronic bronchitis, emphysema, and chronic obstructive pulmonary disease

infants and young children

people who work or exercise outdoors

adults over 65

people with a cardiovascular disease

people in poverty; people who lack access to health care

people who smoke or are exposed to second-hand smoke

people working in occupations where there is high exposure to contaminated air

people who spend a lot of time near busy roadways

The MPCA works to reduce emissions from all sources of air pollution, especially striving to reduce exposures in overburdened communities and work toward environmental justice.

Wood smoke

People who frequently breathe wood smoke are at risk for serious adverse health effects. Wood smoke contains wood tars, gases, and soot, as well as chemicals like carbon monoxide, dioxins, volatile organic compounds (VOCs), and fine particles.

Short-term exposure to fine particles in the air can aggravate lung disease, trigger asthma attacks and acute bronchitis, and may also increase the risk of respiratory infections. Scientists have also linked short-term exposures to heart attacks and abnormal heartbeats. Over time, breathing fine particles in the air increases the chances of developing chronic obstructive lung disease (COPD), chronic bronchitis, cardiovascular disease, or lung cancer. In high concentrations, wood smoke can permanently damage lung tissue.

Indoor air

We tend to think of air pollution as something outside, but the air inside homes, offices, and other buildings can be more polluted than outdoor air. On average, Americans spend approximately 90% of their time indoors, where the concentrations of some pollutants are often two to five times higher than outdoor concentrations. Moreover, people who are most susceptible to the effects of pollution (e.g., the very young, older adults, people with cardiovascular or respiratory disease) tend to spend even more time indoors.

Common indoor air pollutants include radon, smoke, and lead dust. Carbon monoxide from a faulty furnace, mold from damp walls, or volatile organic compounds from a newly painted room also contaminate indoor air. Pollutants such as fine particles from candles or fireplaces (or from the outdoors) also affect our health.

Biological pollutants-such as mold, pollen, animal dander, dust mites, and cockroaches-may trigger breathing problems, allergic symptoms, or asthma attacks. Tobacco smoke contains some 200 known poisons, such as formaldehyde and carbon monoxide, and at least 60 chemicals known to cause cancer. Radon is the second leading cause of lung cancer in the U.S.

For details on common indoor air pollutants, asthma, indoor air quality in schools, and more, visit Air quality, climate & health (Minnesota Department of Health).

Take steps to protect your health

Know when air quality is unhealthy - Check out the MPCA Air Quality Index and sign up for air quality forecasts and alerts.

Protect yourself while driving - Close your windows when you're in traffic and set your ventilation system to recirculate the air to avoid breathing vehicle exhaust. Choose driving routes that are less traveled, especially by diesel vehicles.

Avoid exposure to pollutants - Keep away from wood smoke, vehicle exhaust, tobacco smoke, and other sources of airborne particles, where possible. Avoid prolonged outdoor exertion near busy roadways or on days when the air quality is poor.

Science and data

Cumulative health effects

When projects or actions are proposed that might affect pollution levels in an area, communities want to know how it will affect human health when combined with other pollutants and stressors in their community. Many large and small sources of air pollution contribute to an individual's exposure. The MPCA developed a risk-screening tool called MNRISKS to help understand this cumulative impact of air pollution on Minnesotans. MNRISKS is refreshed every three years when air toxics emissions inventory data is released.

MNRISKS compares air pollution levels against health benchmarks to estimate the potential for negative health effects. A health benchmark is an amount of air pollution that is unlikely to result in health effects after a specific exposure period.

Higher scores mean higher risks, but don't necessarily mean that health effects are occurring in an area. MNRISKS helps regulators prioritize emission reduction activities, air monitoring locations, and other efforts to improve air quality. These may include focusing on specific pollutants or geographic areas, double-checking estimates of air emissions provided by permittees, and identifying disproportionate impacts to specific populations.

Air toxicity benchmarks and risk assessment

We use specific benchmark values for risk assessment. We compare air concentrations of pollutants to these health benchmarks to assess for potential health effects.

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Exposure to air pollution can affect everyone's health.

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Where Does Air Pollution Come From? The National Park Service

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Where Does Air Pollution Come From? The National Park Service

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Where Does Air Pollution Come From? - Air (U.S. National Park Service)

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air quality, air pollution, sources, stationary, mobile, wildfires, emissions, power plants, automobiles, sulfur dioxide, nitrogen oxides, particulate matter, ozone, volatile organic compounds, toxics, nitrogen, sulfur, heavy metals, transport

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WHO fact sheet on ambient (outdoor) air quality guidelines: includes key facts, definition, health effects, guideline values and WHO response.

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National Institute of Environmental Health Sciences, Air Pollution and Your Health

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National Institute of Environmental Health Sciences, Air Pollution and Your Health

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National Institute of Environmental Health Sciences

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Introduction

Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

It is a major threat to global health and prosperity. Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, a number that has increased over the past two decades.

What Is Air Pollution?

Air pollution is a mix of hazardous substances from both human-made and natural sources.

Vehicle emissions, fuel oils and natural gas to heat homes, by-products of manufacturing and power generation, particularly coal-fueled power plants, and fumes from chemical production are the primary sources of human-made air pollution.

Nature releases hazardous substances into the air, such as smoke from wildfires, which are often caused by people; ash and gases from volcanic eruptions; and gases, like methane, which are emitted from decomposing organic matter in soils.

Traffic-Related Air Pollution (TRAP), a mixture of gasses and particles, has most of the elements of human-made air pollution: ground-level ozone, various forms of carbon, nitrogen oxides, sulfur oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, and fine particulate matter.

Ozone, an atmospheric gas, is often called smog when at ground level. It is created when pollutants emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in the presence of sunlight.

Noxious gases, which include carbon dioxide, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx), are components of motor vehicle emissions and byproducts of industrial processes.

Particulate matter (PM) is composed of chemicals such as sulfates, nitrates, carbon, or mineral dusts. Vehicle and industrial emissions from fossil fuel combustion, cigarette smoke, and burning organic matter, such as wildfires, all contain PM.

A subset of PM, fine particulate matter (PM 2.5) is 30 times thinner than a human hair. It can be inhaled deeply into lung tissue and contribute to serious health problems. PM 2.5 accounts for most health effects due to air pollution in the U.S.

Volatile organic compounds (VOC) vaporize at or near room temperature-hence, the designation volatile. They are called organic because they contain carbon. VOCs are given off by paints, cleaning supplies, pesticides, some furnishings, and even craft materials like glue. Gasoline and natural gas are major sources of VOCs, which are released during combustion.

Polycyclic aromatic hydrocarbons (PAH) are organic compounds containing carbon and hydrogen. Of more than 100 PAHs known to be widespread in the environment, 15 are listed in the Report on Carcinogens. In addition to combustion, many industrial processes, such as iron, steel, and rubber product manufacturing, as well as power generation, also produce PAHs as a by-product. PAHs are also found in particulate matter.

Air Pollution and Climate Change

Air pollution and climate change affect each other through complex interactions in the atmosphere. Air pollution is intricately linked with climate change because both problems come largely from the same sources, such as emissions from burning fossil fuels. Both are threats to people's health and the environment worldwide. Read more: Health Impacts of Air Quality.

What is NIEHS Doing?

Over its 50-plus year history, NIEHS has been a leader in air pollution research. The institute continues to fund and conduct research into how air pollution affects health and the population groups who are most affected.

How does air pollution affect our health?

When the National Ambient Air Quality Standards were established in 1970, air pollution was regarded primarily as a threat to respiratory health. In 1993, NIEHS researchers published the landmark Six Cities Study, which established an association between fine particulate matter and mortality.

Air pollution exposure is associated with oxidative stress and inflammation in human cells, which may lay a foundation for chronic diseases and cancer. In 2013, the International Agency for Research on Cancer of the World Health Organization (WHO) classified air pollution as a human carcinogen.

Mortality rates related to air pollution are a concern. Exposure to the air pollutant PM2.5 is associated with an increased risk of death.

A team of researchers, partially funded by NIEHS, found that deaths decreased after air pollution regulations were implemented and coal-powered plants were retired. The study data covered 21 years. More specifically, they found exposure to PM2.5 from coal was associated with a mortality risk that was twice as high as the risk from exposure to PM2.5 from all sources. PM2.5 from coal is high in sulfur dioxide, black carbon, and metals.

Public health concerns include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders.

Research on air pollution and health effects continually advances.

Cancer

A large study of more than 57,000 women found living near major roadways may increase a woman's risk for breast cancer.

The NIEHS Sister Study found other airborne toxic substances, especially methylene chloride, which is used in aerosol products and paint removers, are also associated with increased risk of breast cancer.

Occupational exposure to benzene, an industrial chemical and component of gasoline, can cause leukemia and is associated with non-Hodgkin's Lymphoma.

A long-term study, 2000-2016, found an association between lung cancer incidence and increased reliance on coal for energy generation.

Cardiovascular Disease

Fine particulate matter can impair blood vessel function and speed up calcification in arteries.

NIEHS researchers established links between short-term daily exposure by post-menopausal women to nitrogen oxides and increased risk of hemorrhagic stroke.

For some older Americans, exposure to TRAP can result in lowered levels of high-density lipoprotein, sometimes called good cholesterol, increasing their risk for cardiovascular disease.

According to a National Toxicology Program (NTP) , TRAP exposure also increases a pregnant woman's risk for dangerous changes in blood pressure, known as hypertensive disorders, which are a leading cause of pre-term birth, low birth weight, and maternal and fetal illness and death.

Respiratory Disease

Air pollution can affect lung development and is implicated in the development of , asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease (COPD).

Increases in asthma prevalence and severity are linked to urbanization and outdoor air pollution. Children living in low-income urban areas tend to have more asthma cases than others. Research published in 2023 tied two air pollutants, ozone and PM2.5, to asthma-related changes in children's airways.

PM and nitrogen oxide are linked to chronic bronchitis.

In 2020, a major public health challenge was confluence of the COVID-19 pandemic and wildfires across the western U.S. Building on a well-established connection between air pollution and respiratory-tract infections, a study linked wildfire smoke with additional COVID-19 cases and deaths.

Whom does air pollution affect the most?

Air pollution affects everyone's health, but certain groups may be harmed more.
Almost 9 out of 10 people who live in urban areas worldwide are affected by air pollution.
Children
The NIEHS-funded Children's Health Study at the University of Southern California is one of the largest studies of the long-term effects of air pollution on children's respiratory health. Among its findings:

Higher air pollution levels increase short-term respiratory infections, which lead to more school absences.

Children who play several outdoor sports and live in high ozone communities are more likely to develop asthma.

Children living near busy roads are at increased risk for asthma.

Children with asthma who were exposed to high levels of air pollutants were more likely to develop bronchitis symptoms.

Living in communities with higher pollution levels can cause lung damage.

Other studies on women and children

NIEHS-funded researchers from the University of California, Davis, Environmental Health Sciences Center are conducting the Bio-Specimen and Fire Effects (B-SAFE) Study. This ongoing project seeks to discover if and how recent wildfires and their smoke affected pregnant women and their babies. Begun in 2017, study participants are pregnant women who were living in Northern California when the 2018, 2019, or 2020 wildfires occurred there.

Breathing PM 2.5, even at relatively low levels, may alter the size of a child's developing brain, which may ultimately increase the risk for cognitive and emotional problems later in adolescence.

Prenatal exposure to PAHs was associated with brain development effects, slower processing speed, attention-deficit and hyperactivity disorder (ADHD) symptoms, and other neurobehavioral problems in urban youth.

In New York City, prenatal exposure to air pollution may play a role in childhood ADHD-related behavior problems.

Prenatal exposure to particulate matter was associated with low birth weight.

Women exposed to high levels of fine particulate matter during pregnancy, particularly in the third trimester, may have up to twice the risk of having a child with autism.

Second and third trimester exposure to PM 2.5 might increase the chance of those children having high blood pressure in early life.

In California's agricultural San Joaquin Valley, women who were exposed to high levels of carbon monoxide, nitrogen oxide, or nitrogen dioxide during their first 8 weeks of pregnancy were more likely to have a baby with neural tube defects.

In Marietta, Ohio, home to a ferromanganese refinery, manganese concentrations in blood and hair, a biomarker of air pollution exposure, were associated with lower child IQ scores.

Older adults

Alzheimer's disease and related dementias are a public health challenge for aging populations. NIEHS-funded researchers at the University of Washington identified a link between air pollution and dementias. This well-conducted study adds considerable evidence that ambient air fine particles increase risk of dementias. Conversely, a multi-year study published in 2022 shows improved air quality is associated with lower risk of dementia in older women. The researchers also stated this decline in dementia risk was equivalent to taking nearly 2 1/2 years off the age of the women studied.

Air pollution was linked to a greater chance of developing several neurological disorders, including Parkinson's disease, Alzheimer's disease, and other dementias. Hospital admissions data from 63 million older adults in the U.S., obtained over 17 years (2000-2016), was analyzed along with estimated PM 2.5 concentrations by zip code to conduct the study.

In older adults, long-term exposure to TRAP may significantly hasten physical disabilities. The risk is more pronounced among racial minorities and lower-income people.

Osteoporosis affects women more than men. A large study associated high levels of air pollutants with bone damage, particularly in the lumbar spine, among postmenopausal women. This study expands previous findings linking air pollution and bone damage.

Nutrients may counter some harmful effects from air pollution. A 2020 study found omega-3 fatty acids, obtained by eating certain fish, may protect against PM 2.5-associated brain shrinkage in older women.

Rural dwellers

An NIEHS-funded study found that concentrations of PM 2.5 in rural Washington State were comparable to urban Seattle. In this study, as regional PM 2.5 increased, there were increased asthma symptoms, such as limitation of activities, more wheezing, and more nighttime waking, in rural children.

NIEHS supported a translational research project, Addressing Air Pollution and Asthma, that may lead to improved health for children suffering from asthma. They found that certain agricultural practices contribute to poor air quality and asthma among children. The team combined high-efficiency particulate air (HEPA) cleaners and a home-based education program to reduce children's exposure to pollutants in the home.

In the rural U.S., large-scale animal feeding operations might compromise regional air quality through emission of pollutants, such as ammonia gas. A study found acute lung function problems in children with asthma in such areas.

Different genes
Your genes play a role in respiratory health. NIEHS-funded research discovered that people with specific gene variants, which made them more likely to have lung inflammation, had a greater chance of suffering from asthma if they lived close to major roadways.

NIEHS and community involvement

NIEHS supports community participation in the research process and encourages collaborative approaches that build capacity in communities to address environmental health concerns. Community-engaged research and citizen science are two types of collaborative research approaches.

For example, NIEHS helps residents of Imperial County, California track air pollution through a network of 40 community-run monitors. In this county, long-term improvements in air quality were associated with significant lung-function improvement in children.

In another example, NIEHS grant recipients developed community-level tactics and public policies for reducing exposure to TRAP:

Using high-efficiency particulate air (HEPA) filtration.

Building land-use buffers and vegetation barriers.

Improving urban design with gardens, parks, and street-side trees.

Creating active-travel options, such as bicycling and walking paths.

THE (Trade, Health, Environment) Impact Project brings together researchers and community groups to find solutions for communities affected by trade-related pollution, such as ports and roadways with trucking.

Why improving air quality matters

Air pollution and birth outcomes are linked as global public health concerns. Researchers analyzed indoor and outdoor air pollution data from all inhabited continents along with key pregnancy outcomes. Their findings indicate efforts to reduce PM2.5 exposure could lead to significant reductions in the number of low-birth weight and pre-term birth infants worldwide. Air pollution reduction would be especially beneficial for children born in low- and middle-income countries.

Among children in Southern California, decreases in ambient nitrogen dioxide and PM 2.5 were associated with fewer cases of asthma.

An NIEHS-funded study found that a mixture of several B vitamins may protect DNA from changes attributable to PM 2.5 air pollution.

Bronchitis symptoms declined as pollution levels dropped in the Los Angeles region.

Improving air quality may improve cognitive function and reduce dementia risk, according to supported in part by NIH and the Alzheimer's Association.

When fossil-fuel power plants close, nearby air pollution is reduced. A study found the incidence of preterm births went down within 5 kilometers of retired coal and oil-powered plant locations.

Further Reading

Stories from the Environmental Factor (NIEHS Newsletter)

Printable Fact Sheets

Podcasts

Additional Resources

Air Pollution Linked to Dementia Cases (September 2023) - In this edition of NIH Research Matters, read about findings from the Health and Retirement Study, funded by the National Institute on Aging, that showed higher air pollution exposure was linked to an increased risk of dementia. After consideration of all sources, fine particulate matter, or PM2.5, from agriculture and wildfires were specifically associated with an increased risk of dementia. Reducing such exposures might help lower the incidence of dementia. The study was published in JAMA Internal Medicine.

, a tool developed in partnership by several government agencies, allows you to monitor air quality in real time anywhere in the U.S. Simply enter your zip code as indicated on the website.

EPA's Air Sensor Toolbox provides information on the operation and use of air-sensor monitoring systems for technology developers, air-quality managers, citizen scientists, and the public.

NIH Climate Change and Health Initiative - This solutions-focused research initiative aims to reduce the health consequences associated with extreme weather events and evolving climate conditions. NIH has a strong history of creating innovative tools, technologies, and data-driven solutions to address global environmental problems.

Smoke-ready Toolbox for Wildfires is a compendium of resources from the EPA to help educate you about the risks of smoke exposure and actions that protect your health.

Wildfire Smoke Collection - The journal Environmental Health Perspectives has published high-impact papers and reviews exploring exposure and resulting health effects related to wildfires.

Related Health Topics

This content is available to use on your website.

Please visit NIEHS Syndication to get started.

Introduction

Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

It is a major threat to global health and prosperity. Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, a number that has increased over the past two decades.

What Is Air Pollution?

Air pollution is a mix of hazardous substances from both human-made and natural sources.

Vehicle emissions, fuel oils and natural gas to heat homes, by-products of manufacturing and power generation, particularly coal-fueled power plants, and fumes from chemical production are the primary sources of human-made air pollution.

Nature releases hazardous substances into the air, such as smoke from wildfires, which are often caused by people; ash and gases from volcanic eruptions; and gases, like methane, which are emitted from decomposing organic matter in soils.

Traffic-Related Air Pollution (TRAP), a mixture of gasses and particles, has most of the elements of human-made air pollution: ground-level ozone, various forms of carbon, nitrogen oxides, sulfur oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, and fine particulate matter.

Ozone, an atmospheric gas, is often called smog when at ground level. It is created when pollutants emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in the presence of sunlight.

Noxious gases, which include carbon dioxide, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx), are components of motor vehicle emissions and byproducts of industrial processes.

Particulate matter (PM) is composed of chemicals such as sulfates, nitrates, carbon, or mineral dusts. Vehicle and industrial emissions from fossil fuel combustion, cigarette smoke, and burning organic matter, such as wildfires, all contain PM.

A subset of PM, fine particulate matter (PM 2.5) is 30 times thinner than a human hair. It can be inhaled deeply into lung tissue and contribute to serious health problems. PM 2.5 accounts for most health effects due to air pollution in the U.S.

Volatile organic compounds (VOC) vaporize at or near room temperature-hence, the designation volatile. They are called organic because they contain carbon. VOCs are given off by paints, cleaning supplies, pesticides, some furnishings, and even craft materials like glue. Gasoline and natural gas are major sources of VOCs, which are released during combustion.

Polycyclic aromatic hydrocarbons (PAH) are organic compounds containing carbon and hydrogen. Of more than 100 PAHs known to be widespread in the environment, 15 are listed in the Report on Carcinogens. In addition to combustion, many industrial processes, such as iron, steel, and rubber product manufacturing, as well as power generation, also produce PAHs as a by-product. PAHs are also found in particulate matter.

Air Pollution and Climate Change

Air pollution and climate change affect each other through complex interactions in the atmosphere. Air pollution is intricately linked with climate change because both problems come largely from the same sources, such as emissions from burning fossil fuels. Both are threats to people's health and the environment worldwide. Read more: Health Impacts of Air Quality.

What is NIEHS Doing?

Over its 50-plus year history, NIEHS has been a leader in air pollution research. The institute continues to fund and conduct research into how air pollution affects health and the population groups who are most affected.

How does air pollution affect our health?

When the National Ambient Air Quality Standards were established in 1970, air pollution was regarded primarily as a threat to respiratory health. In 1993, NIEHS researchers published the landmark Six Cities Study, which established an association between fine particulate matter and mortality.

Air pollution exposure is associated with oxidative stress and inflammation in human cells, which may lay a foundation for chronic diseases and cancer. In 2013, the International Agency for Research on Cancer of the World Health Organization (WHO) classified air pollution as a human carcinogen.

Mortality rates related to air pollution are a concern. Exposure to the air pollutant PM2.5 is associated with an increased risk of death.

A team of researchers, partially funded by NIEHS, found that deaths decreased after air pollution regulations were implemented and coal-powered plants were retired. The study data covered 21 years. More specifically, they found exposure to PM2.5 from coal was associated with a mortality risk that was twice as high as the risk from exposure to PM2.5 from all sources. PM2.5 from coal is high in sulfur dioxide, black carbon, and metals.

Public health concerns include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders.

Research on air pollution and health effects continually advances.

Cancer

A large study of more than 57,000 women found living near major roadways may increase a woman's risk for breast cancer.

The NIEHS Sister Study found other airborne toxic substances, especially methylene chloride, which is used in aerosol products and paint removers, are also associated with increased risk of breast cancer.

Occupational exposure to benzene, an industrial chemical and component of gasoline, can cause leukemia and is associated with non-Hodgkin's Lymphoma.

A long-term study, 2000-2016, found an association between lung cancer incidence and increased reliance on coal for energy generation.

Cardiovascular Disease

Fine particulate matter can impair blood vessel function and speed up calcification in arteries.

NIEHS researchers established links between short-term daily exposure by post-menopausal women to nitrogen oxides and increased risk of hemorrhagic stroke.

For some older Americans, exposure to TRAP can result in lowered levels of high-density lipoprotein, sometimes called good cholesterol, increasing their risk for cardiovascular disease.

According to a National Toxicology Program (NTP) , TRAP exposure also increases a pregnant woman's risk for dangerous changes in blood pressure, known as hypertensive disorders, which are a leading cause of pre-term birth, low birth weight, and maternal and fetal illness and death.

Respiratory Disease

Air pollution can affect lung development and is implicated in the development of , asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease (COPD).

Increases in asthma prevalence and severity are linked to urbanization and outdoor air pollution. Children living in low-income urban areas tend to have more asthma cases than others. Research published in 2023 tied two air pollutants, ozone and PM2.5, to asthma-related changes in children's airways.

PM and nitrogen oxide are linked to chronic bronchitis.

In 2020, a major public health challenge was confluence of the COVID-19 pandemic and wildfires across the western U.S. Building on a well-established connection between air pollution and respiratory-tract infections, a study linked wildfire smoke with additional COVID-19 cases and deaths.

Whom does air pollution affect the most?

Air pollution affects everyone's health, but certain groups may be harmed more.
Almost 9 out of 10 people who live in urban areas worldwide are affected by air pollution.
Children
The NIEHS-funded Children's Health Study at the University of Southern California is one of the largest studies of the long-term effects of air pollution on children's respiratory health. Among its findings:

Higher air pollution levels increase short-term respiratory infections, which lead to more school absences.

Children who play several outdoor sports and live in high ozone communities are more likely to develop asthma.

Children living near busy roads are at increased risk for asthma.

Children with asthma who were exposed to high levels of air pollutants were more likely to develop bronchitis symptoms.

Living in communities with higher pollution levels can cause lung damage.

Other studies on women and children

NIEHS-funded researchers from the University of California, Davis, Environmental Health Sciences Center are conducting the Bio-Specimen and Fire Effects (B-SAFE) Study. This ongoing project seeks to discover if and how recent wildfires and their smoke affected pregnant women and their babies. Begun in 2017, study participants are pregnant women who were living in Northern California when the 2018, 2019, or 2020 wildfires occurred there.

Breathing PM 2.5, even at relatively low levels, may alter the size of a child's developing brain, which may ultimately increase the risk for cognitive and emotional problems later in adolescence.

Prenatal exposure to PAHs was associated with brain development effects, slower processing speed, attention-deficit and hyperactivity disorder (ADHD) symptoms, and other neurobehavioral problems in urban youth.

In New York City, prenatal exposure to air pollution may play a role in childhood ADHD-related behavior problems.

Prenatal exposure to particulate matter was associated with low birth weight.

Women exposed to high levels of fine particulate matter during pregnancy, particularly in the third trimester, may have up to twice the risk of having a child with autism.

Second and third trimester exposure to PM 2.5 might increase the chance of those children having high blood pressure in early life.

In California's agricultural San Joaquin Valley, women who were exposed to high levels of carbon monoxide, nitrogen oxide, or nitrogen dioxide during their first 8 weeks of pregnancy were more likely to have a baby with neural tube defects.

In Marietta, Ohio, home to a ferromanganese refinery, manganese concentrations in blood and hair, a biomarker of air pollution exposure, were associated with lower child IQ scores.

Older adults

Alzheimer's disease and related dementias are a public health challenge for aging populations. NIEHS-funded researchers at the University of Washington identified a link between air pollution and dementias. This well-conducted study adds considerable evidence that ambient air fine particles increase risk of dementias. Conversely, a multi-year study published in 2022 shows improved air quality is associated with lower risk of dementia in older women. The researchers also stated this decline in dementia risk was equivalent to taking nearly 2 1/2 years off the age of the women studied.

Air pollution was linked to a greater chance of developing several neurological disorders, including Parkinson's disease, Alzheimer's disease, and other dementias. Hospital admissions data from 63 million older adults in the U.S., obtained over 17 years (2000-2016), was analyzed along with estimated PM 2.5 concentrations by zip code to conduct the study.

In older adults, long-term exposure to TRAP may significantly hasten physical disabilities. The risk is more pronounced among racial minorities and lower-income people.

Osteoporosis affects women more than men. A large study associated high levels of air pollutants with bone damage, particularly in the lumbar spine, among postmenopausal women. This study expands previous findings linking air pollution and bone damage.

Nutrients may counter some harmful effects from air pollution. A 2020 study found omega-3 fatty acids, obtained by eating certain fish, may protect against PM 2.5-associated brain shrinkage in older women.

Rural dwellers

An NIEHS-funded study found that concentrations of PM 2.5 in rural Washington State were comparable to urban Seattle. In this study, as regional PM 2.5 increased, there were increased asthma symptoms, such as limitation of activities, more wheezing, and more nighttime waking, in rural children.

NIEHS supported a translational research project, Addressing Air Pollution and Asthma, that may lead to improved health for children suffering from asthma. They found that certain agricultural practices contribute to poor air quality and asthma among children. The team combined high-efficiency particulate air (HEPA) cleaners and a home-based education program to reduce children's exposure to pollutants in the home.

In the rural U.S., large-scale animal feeding operations might compromise regional air quality through emission of pollutants, such as ammonia gas. A study found acute lung function problems in children with asthma in such areas.

Different genes
Your genes play a role in respiratory health. NIEHS-funded research discovered that people with specific gene variants, which made them more likely to have lung inflammation, had a greater chance of suffering from asthma if they lived close to major roadways.

NIEHS and community involvement

NIEHS supports community participation in the research process and encourages collaborative approaches that build capacity in communities to address environmental health concerns. Community-engaged research and citizen science are two types of collaborative research approaches.

For example, NIEHS helps residents of Imperial County, California track air pollution through a network of 40 community-run monitors. In this county, long-term improvements in air quality were associated with significant lung-function improvement in children.

In another example, NIEHS grant recipients developed community-level tactics and public policies for reducing exposure to TRAP:

Using high-efficiency particulate air (HEPA) filtration.

Building land-use buffers and vegetation barriers.

Improving urban design with gardens, parks, and street-side trees.

Creating active-travel options, such as bicycling and walking paths.

THE (Trade, Health, Environment) Impact Project brings together researchers and community groups to find solutions for communities affected by trade-related pollution, such as ports and roadways with trucking.

Why improving air quality matters

Air pollution and birth outcomes are linked as global public health concerns. Researchers analyzed indoor and outdoor air pollution data from all inhabited continents along with key pregnancy outcomes. Their findings indicate efforts to reduce PM2.5 exposure could lead to significant reductions in the number of low-birth weight and pre-term birth infants worldwide. Air pollution reduction would be especially beneficial for children born in low- and middle-income countries.

Among children in Southern California, decreases in ambient nitrogen dioxide and PM 2.5 were associated with fewer cases of asthma.

An NIEHS-funded study found that a mixture of several B vitamins may protect DNA from changes attributable to PM 2.5 air pollution.

Bronchitis symptoms declined as pollution levels dropped in the Los Angeles region.

Improving air quality may improve cognitive function and reduce dementia risk, according to supported in part by NIH and the Alzheimer's Association.

When fossil-fuel power plants close, nearby air pollution is reduced. A study found the incidence of preterm births went down within 5 kilometers of retired coal and oil-powered plant locations.

Further Reading

Stories from the Environmental Factor (NIEHS Newsletter)

Printable Fact Sheets

Podcasts

Additional Resources

Air Pollution Linked to Dementia Cases (September 2023) - In this edition of NIH Research Matters, read about findings from the Health and Retirement Study, funded by the National Institute on Aging, that showed higher air pollution exposure was linked to an increased risk of dementia. After consideration of all sources, fine particulate matter, or PM2.5, from agriculture and wildfires were specifically associated with an increased risk of dementia. Reducing such exposures might help lower the incidence of dementia. The study was published in JAMA Internal Medicine.

, a tool developed in partnership by several government agencies, allows you to monitor air quality in real time anywhere in the U.S. Simply enter your zip code as indicated on the website.

EPA's Air Sensor Toolbox provides information on the operation and use of air-sensor monitoring systems for technology developers, air-quality managers, citizen scientists, and the public.

NIH Climate Change and Health Initiative - This solutions-focused research initiative aims to reduce the health consequences associated with extreme weather events and evolving climate conditions. NIH has a strong history of creating innovative tools, technologies, and data-driven solutions to address global environmental problems.

Smoke-ready Toolbox for Wildfires is a compendium of resources from the EPA to help educate you about the risks of smoke exposure and actions that protect your health.

Wildfire Smoke Collection - The journal Environmental Health Perspectives has published high-impact papers and reviews exploring exposure and resulting health effects related to wildfires.

Related Health Topics

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Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

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The United Nations Environment Programme (UNEP) strengthens global solidarity and political momentum for action to improve air quality. Through initiatives such as the International Day of Clean Air for blue skies, Beat Pollution and Breathe Life, UNEP and its partners seek to raise awareness of the importance of clean air. UNEP bolsters scientific evidence, improves data quality, and provides tools to help governments, the private sector, and communities to make informed decisions and take actions for clean air, health, and livelihoods. Resources: International Day of Clean Air for blue skies, observed on September 7 since 2019, offers a platform to encourage global collaboration to fight air pollution and preserve ecosystems, emphasizing the importance of improving air quality for human and environmental well-being at all levels: individual, national, regional and international. Explore this practical Guide on Clean Air for blue skies and how to claim your right for clean air (video). The Beat Pollution campaign builds on a larger narrative for a pollution-free planet, by linking climate, nature and different pollution streams. Tasked by the UN Environment Assembly, UNEP coordinates “Towards a Pollution-Free Planet,” a plan to eradicate all pollution by 2030, focusing on improved chemical and waste management for human and environmental health and increasing circular processes. Breathe Life is a global campaign, led by World Health Organization (WHO), UNEP and the Climate & Clean Air Coalition (CCAC). It calls on governments - city, regional and national - to commit to achieving WHO Air Quality Guidelines by 2030. Reducing air pollution to levels deemed safe by the WHO will halve the number of air pollution related deaths by 2030, while at the same time helping to slow the rate of climate change.