Key Findings

Learn the key findings and overall trends about air quality in states and cities in the American Lung Association's State of the Air report.
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The “State of the Air” 2024 report finds that despite decades of progress cleaning up air pollution, 39% of Americans—131.2 million people—still live in places with failing grades for unhealthy levels of ozone or particle pollution. This is 11.7 million more people breathing unhealthy air compared to last year’s report. 

more than one in three

More than 4 in 10 people in America live in places with unhealthy levels of air pollution.

The significant rise in the number of individuals whose health is at risk is the result of a combination of factors. Extreme heat, drought and wildfires are contributing to a steady increase in deadly particle pollution, especially in the western U.S. Also, this year’s “State of the Air” report is using EPA’s new, more protective national air quality standard for year-round levels of fine particle pollution, which allows for the recognition that many more people are breathing unhealthy air than was acknowledged under the previous weak standard.

Again this year, “State of the Air” finds that the burden of living with unhealthy air is not shared equally. Although people of color make up 41.6% of the overall population of the U.S., they are 52% of the people living in a county with at least one failing grade. In the counties with the worst air quality that get failing grades for all three measures of air pollution, 63% of the nearly 44 million residents are people of color, compared to 37% who are white.

Circle graphic with 3.6X overlayed.

People of color were 2.3 times as likely as white people to live in a county with 3 failing grades.

The “State of the Air” report looks at two of the most widespread and dangerous air pollutants, fine particles and ozone. The air quality data used in the report are collected at official monitoring sites across the United States by the federal, state, local and Tribal governments. The Lung Association calculates values reflecting the air pollution problem and assigns grades for daily and long-term measures of particle pollution and daily measures of ozone. Those values are also used to rank cities (metropolitan areas) and counties. This year’s report presents data from 2020, 2021 and 2022, the most recent quality-assured nationwide air pollution data publicly available. See About This Report for more detail about the methodology for data collection and analysis.

“State of the Air” 2024 is the 25th edition of this annual report, which was first published in 2000. From the beginning, the findings in “State of the Air” have reflected the successes of the Clean Air Act, as emissions from transportation, power plants and manufacturing have been reduced. In recent years, however, the findings of the report continue adding to the evidence that a changing climate is making it harder to protect human health. High ozone days and spikes in particle pollution related to extreme heat, drought and wildfires are putting millions of people at risk and adding challenges to the work that states and cities are doing across the nation to clean up air pollution.

"When we started doing “State of the Air” in the 2000, I never imagined that in the 25th edition we would be reporting that more than 100 million people are still breathing unhealthy air. It’s unacceptable."

Paul Billings, American Lung Association

The combination of policy-driven reductions in emissions on the one hand and climate change-fueled increases in pollution on the other hand have resulted in an ongoing and marked disparity between air quality in eastern and western states, especially for the daily measure of fine particle pollution. In this year’s report, only 4 large counties in three states east of the Mississippi River, earned failing grades for daily spikes in fine particle pollution, compared to 108 counties in 16 western states. 

Thermometer with arrow pointing up

Climate change is making the job of cleaning up the air more difficult.

When looking at levels of year-round particle pollution, however, the story becomes more nuanced. The majority of the 119 counties earning failing grades for year-round particle pollution are in the western U.S., but the new, stronger standard is revealing remaining air quality problems in eastern and midwestern states. In “State of the Air” 2024 there were 47 counties in 12 states east of the Mississippi River with unhealthy year-round levels of fine particles. 

In “State of the Air” 2024, the metropolitan areas that ranked worst in the country for each of the three pollutant measures were unchanged from last year’s report.  Bakersfield, California topped the list for worst short-term particle pollution again this year. Bakersfield also continued as the metropolitan area with the worst level of year-round particle pollution for the 5th year in a row. Los Angeles remains the city with the worst ozone pollution in the nation, as it has been in 24 of the 25 years of reporting in “State of the Air”– even though city residents are exposed to unhealthy levels of ozone an average of 55 days a year fewer than now than they were in 2000.

More Findings

Ozone Trends

Exposure to unhealthy levels of ozone air pollution continues to make breathing difficult for millions of Americans.
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Short-Term Particle Pollution Trends

Many cities reached their highest number of days with unhealthy levels of particle pollution ever reported.
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Year-Round Particle Pollution Trends

More than 20.9 million people live where year-round particle pollution levels are worse than the national air quality limit.
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Populations at Risk

Some groups of people are especially vulnerable to illness and death from exposure to unhealthy levels of air pollution.
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Most Polluted Places

See the 25 most polluted counties for ozone and particle pollution ranked.
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Cleanest Places to Live

Ten cities rank on all three cleanest cities lists for ozone, year-round and short-term particle pollution.
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Recommendations for Action

We need action at every level to clean up air pollution and address climate change.
Learn more

Did You Know?

  1. Nearly four in ten people in the U.S. live where the air they breathe earned an F in “State of the Air” 2024.
  2. More than 131 million people live in counties that received an F for either ozone or particle pollution in “State of the Air” 2024.
  3. Nearly 44 million people live in counties that got an F for all three air pollution measures in “State of the Air” 2024.
  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 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. Particle pollution exposure from wildfire smoke harms health in ways that range from mild irritation to serious illness and premature death.
  20. Recent updates to the Air Quality Index give the public more accurate information about the health risk from air pollution, and when to take measures to protect themselves on bad air days.
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