Populations at Risk

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More than 265 million people live in the 885 counties with enough monitoring data to be assigned a grade for at least one pollutant in this year’s report. The majority of U.S. counties actually don’t have monitors—which means that many communities, especially rural ones, don’t have official monitored information on their air quality.

Addressing Data Gaps in Unmonitored Counties

It is important to note that the population numbers included in this section are only for those places that collect air pollution data, and do not reflect the entire population of these groups in the U.S. The availability of data, and hence the population that is included in this report, differs for each pollutant.

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All 156.1 million people in the U.S. living in places with failing grades for unhealthy levels of ozone or particle pollution are at risk of harm to their health. But some groups of people are especially vulnerable to illness and death from their exposure. See People at Risk for more detail about the factors that contribute to increased risk. 

The number of people in these high-risk groups in “State of the Air” 2025 are as follows: 

  • Children and older adults—More than 34.6 million children under age 18 and some 25.2 million adults age 65 and over live in counties that received an F for at least one pollutant. Close to 9.5 million children and more than 6.7 million seniors live in counties failing all three measures. 
  • People with underlying health conditions 
    • Asthma—More than 2.5 million children and nearly 11.8 million adults with asthma live in counties that received an F for at least one pollutant. More than 638,000 children and some 3.1 million adults with asthma live in counties failing all three measures. 
    • Chronic Obstructive Pulmonary Disease (COPD)—Some 6.8 million people with COPD live in counties that received an F for at least one pollutant. Close to 1.7 million people with COPD live in counties failing all three measures. 
    • Lung Cancer—Nearly 72,000 people diagnosed with lung cancer as of 2021 live in counties that received an F for at least one pollutant, and about 17,500 people ever diagnosed with lung cancer live in counties failing all three measures. 
    • Cardiovascular Disease—Close to 9.7 million people with cardiovascular disease live in counties that received an F for at least one pollutant. Nearly 2.5 million people live in counties failing all three measures. 
    • Pregnancy—Adverse impacts from air pollution have been shown both for those who are pregnant as well as for the developing fetus. More than 1.7 million pregnancies were recorded in 2023 in counties that received at least one failing grade for air pollution. Of those, close to 453,000 were in counties that received failing grades for all three measures. 
  • People experiencing poverty—Nineteen million people with incomes meeting the federal poverty definition live in counties that received an F for at least one pollutant. Close to 5.7 million people in poverty live in counties failing all three measures. 
  • People of color—About 78.3 million people of color live in counties that received at least one failing grade for ozone and/or particle pollution. Over 26.0 million people of color live in counties that received failing grades on all three measures, including some 15.2 million Hispanics. 

Did You Know?

  1. Nearly half of the people in the U.S. live where the air they breathe earned an F in “State of the Air” 2025.
  2. More than 156 million people live in counties that received an F for either ozone or particle pollution in “State of the Air” 2025.
  3. More than 42 million people live in counties that got an F for all three air pollution measures in “State of the Air” 2025.
  4. Breathing ozone irritates the lungs, resulting in inflammation—as if your lungs had a bad sunburn.
  5. Breathing in particle pollution can increase the risk of lung cancer.
  6. Particle pollution can cause early death and heart attacks, strokes, and emergency room visits.
  7. 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.
  8. Ozone and particle pollution are both linked to increased risk of premature birth and lower birth weight in newborns.
  9. If you live or work near a busy highway, traffic pollution may put you at greater risk of health harm.
  10. People who work or exercise outside face increased risk from the effects of air pollution.
  11. 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.
  12. People of color and people with lower incomes are disproportionately affected by air pollution that puts them at higher risk for illness.
  13. Air pollution is a serious health threat. It can trigger asthma attacks, harm lung development in children, and even be deadly.
  14. You can protect yourself by checking the air quality forecast in your community and avoiding exercising or working outdoors when unhealthy air is expected.
  15. Climate change enhances conditions for ozone pollution to form and makes it harder to clean up communities where ozone levels are high.
  16. Climate change increases the risk of wildfires whose smoke spreads dangerous particle pollution.
  17. Policymakers at every level of government must take steps to clean the air their constituents breathe.
  18. 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 50 years.
  19. The U.S. Environmental Protection Agency is critical for cleaning up air pollution. EPA’s staff ensure that air pollution is monitored, write sound rules to clean it up, and make sure those rules are enforced.
  20. The U.S. Environmental Protection Agency is under threat. Despite EPA’s lifesaving role in protecting people’s health from air pollution, big staffing and funding cuts are endangering their work.
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