Nearly half of Americans breathe polluted air

What you probably already know: A growing number of people in the United States live in places with unhealthy levels of air pollution, and the burden is disproportionately impacting some groups. The American Lung Association’s 2025 “State of the Air” study found that 46% of Americans, or more than 156 million people, are breathing unhealthy levels of ozone or particle pollution — that’s nearly 25 million more people than last year and a 10-year historical high for the report, which has been published annually since 2000. People of color make up 41.2% of the national population, but account for 50.2% of Americans living in areas with at least one failing grade for either unhealthy levels of ozone or particle pollution, researchers said. Hispanic individuals are three times as likely as white individuals to live in communities with three failing grades.

Why? Extreme heat, drought, and wildfires are part of the problem. The report identified 211 counties — 93 more than last year — across 35 states and Washington, D.C., that received failing grades for ozone air pollution. Many places, concentrated in the Upper Midwest down to Texas, experienced extreme changes. Of the 137 counties that lost their “A” grade in this report, 10 went from an A to an F. For the northern U.S., worsening ozone was attributed to wildfires in Canada; in the South, it was due to high temperatures and emissions. While wildfire smoke is a conspicuous source of unhealthy particle pollution, researchers said the role wildfires play in ozone formation is complex and difficult to pinpoint.

What is happening? Particle pollution is also worsening: 154 counties in 27 states received failing grades. That’s 44 more counties and eight more states than last year (including Washington, D.C.). Many parts of the West improved, but dozens of counties in the Midwest and East worsened. In this year’s report, more than 56 million people across 25 states were found to have experienced “Very Unhealthy” days (when the health risk increases for all people) and “Hazardous” days (when everyone is more likely to be affected) of fine particle pollution. Researchers said wildfires were a driving factor behind shifts in the location and severity of particle pollution. Areas with the highest particle pollution year-over-year are also subjected to year-round emissions from various sources, such as highways, power plants, and industrial facilities.

What it means: The report pointed out that one bad fire season, like that experienced by Canada in 2023, can offset years of progress in lowering ozone levels. Such setbacks introduce new challenges for air pollution control and put the health of communities at greater risk. It’s also important to point out that most U.S. counties, especially rural counties, don’t have air quality monitors, leaving gaping holes in data. Science has shown that particle pollution and ozone threaten human health, increasing the risk of early birth, causing or worsening lung and heart disease, and shortening lives.

But it’s not all doom and gloom. Ozone levels improved in some parts of the West, including in California, where four cities that are among the 25 worst cities for ozone pollution recorded their fewest-ever number of unhealthy days. All but one of the 10 worst cities for particle pollution improved in this year’s report.

What happens now? The report reinforces the need for urgent action to reduce emissions contributing to air pollution, but progress is stalling at the federal level. As part of the Trump administration’s budget-slashing efforts, the Environmental Protection Agency is canceling nearly 800 grants, including all of those focused on environmental justice. Congress is also poised to overturn an EPA rule on seven toxic air pollutants. The “State of the Air” researchers said sweeping federal cuts are jeopardizing decades of progress driven by the Clean Air Act. They’re calling for people to support EPA staff, who are “vital to ensuring that unhealthy levels of air pollution are not just monitored but also cleaned up,” and defend EPA rules and air quality standards. States and cities also have the power to reduce emissions independently by investing in chargers for electric vehicles and adopting green building policies.