The Clean Air Act requires the U.S. Environmental Protection Agency (EPA) to set health-based limits, called National Ambient Air Quality Standards (NAAQS), for six dangerous outdoor air pollutants: particulate matter, ozone, nitrogen oxides, sulfur dioxide, carbon monoxide and lead. “State of the Air” looks at two of the most widespread and dangerous pollutants from this group, fine particulate matter and ozone.  

The NAAQS identify what is considered a safe level of each pollutant to breathe, based on the most recent health and medical science, including an adequate margin of safety for those most at risk. These standards require states and local governments to take steps to reduce emissions to attain the standards. The standards also serve to alert families with children, seniors, individuals with lung or heart conditions, and others about dangerous air pollution levels through color-coded air quality alerts. This enables them to take necessary precautions to minimize their exposure. Under the Clean Air Act, the standards must be based solely on what is needed to protect health and must be periodically updated as the science evolves.1 

Setting national health-based standards and requiring states that violate the standards to enact plans to clean up their air pollution problems have been a great benefit to the public health of the nation. Since the Clean Air Act was passed in 1970, the combined emissions of six key air pollutants have fallen by 78%, according to EPA. But as “State of the Air” 2024 shows, millions of people in this country are still breathing unhealthy air. 

In the year 2000, the American Lung Association launched its annual “State of the Air” report to provide the public with easy-to-understand information about the quality of the air in their communities based on the credible data and sound science that EPA is required to use to set and enforce the air quality standards.  

For the first several years, “State of the Air” focused solely on ozone pollution and included data for five populations at increased risk – children, older adults, children with asthma, adults with asthma and people with emphysema. In 2004, changes to the air quality standards and the deployment of air pollution monitoring enabled the addition of short-term and year-round fine particle pollution to the report. Over time, accumulating scientific evidence has shown significant health harms from both ozone and particle pollution among other groups of vulnerable individuals. “State of the Air” has accommodated this new information by gradually adding populations-at-risk categories to its reporting. “State of the Air” 2024 now includes data for 10 vulnerable groups. 

Since its inception 25 years ago, “State of the Air” has been tremendously successful in raising awareness about particle pollution and ozone, two of the most dangerous and pervasive air pollutants nationwide. The American Lung Association is proud and grateful that the public, the media, clean air advocates and decision-makers have used this report every day, year after year, to call attention to the work that remains to be done to protect the public from the threat of air pollution.

We write and release “State of the Air” every year to make information on air quality and health clear and accessible to everyone. We show the progress each community has made and how much more needs to be done to achieve healthy air. In this report, you’ll find information on local air quality nationwide. You’ll also find the latest research on how air pollution affects health. With these tools, you can take proactive steps to safeguard both your lungs and your family's lungs from unhealthy air.  

This report also includes ideas for how you can become a champion for clean air. First, we have suggestions for concrete actions you can take to reduce your own contributions to air pollution and climate change. And second, we invite you to take advocacy action with the American Lung Association. Our report includes policy recommendations for every level of government. Your voice is powerful, and when you tell your leaders that your lungs depend on stronger limits on air pollution, you make a compelling case. Please share your story and add your name to our petition – and then, take the next step. Reach out to your representatives at every level of government, share the “State of the Air” results for your community, and call on them to take action to protect public health.

For long-time Los Angeles area residents, poor air quality isn’t always top of mind, with smog and bad air days a regular occurrence.

Lee M. has lived in Southern California for 12 years. The change in air quality is noticeable when away, such as during his visits to Portland, Oregon.

“When you go to other places, you realize it’s not as fresh as it could be,” he says. “There’s that feeling when you get off the train in Portland – it’s green, I can breathe and it doesn’t smell like cars.”

Lee considers air quality when choosing where to live. He avoids living near freeways due to noise and air concerns but still has to regularly clean his porch of soot and dust, especially when winds blow wildfire smoke into the region.

“Clean air makes for a better place to be.”

Lee M.
West Hollywood, California

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.
Get More Facts
Take Action
  1. In February 2024, after a lengthy wait, EPA announced a new, more protective annual standard for fine particle pollution. That standard is being used in the 2024 “State of the Air” report. The ozone standard is also overdue for a revision based on the science, but that process has faced multiple delays.

Page last updated: June 7, 2024