156 Million Americans Now Breathe Unhealthy Air - Here's Where The Air Is Cleanest And Dirtiest

For more than a quarter-century, the American Lung Association has taken the pulse of our nation’s air quality with its annual “State of the Air” report. Now, the 2025 edition has delivered a jarring message: America’s air is getting dirtier again following years of small improvements.

The 2025 report reveals that nearly half of the U.S. population—156.1 million people—live in areas with failing grades for ozone or particle pollution. That’s 25 million more people than last year, marking the highest number in the past decade. The reasons? A potent mix of extreme heat, worsening drought, and growing wildfires - all of which are intensifying air pollution across the country.

This year’s analysis pulls data from the years 2021-2023, using official air quality monitors across the nation. It focuses on two major health threats: fine particulate matter (aka soot) and ground-level ozone (aka smog). Both are well-known culprits behind respiratory and heart problems, and both are rising in many areas, despite past progress.

(MORE: The Scary Truth About Lingering Wildfire Smoke)

The Best And The Worst

For years, the worst air quality offenders were mostly in the western U.S. But the 2025 report shows a shift—smoke from Canadian wildfires and a deadly heat wave in Texas pushed pollution levels higher across central and eastern states, reshaping the national pollution map.

However, the cities with the worst grades were still concentrated in the west, specifically California:

• Bakersfield, CA ranks worst for both short-term and year-round particle pollution.
• Los Angeles, CA continues its 25-of-26-year reign as the smoggiest city in the country, though Angelenos are breathing somewhat easier than they did in 2000—with 77 fewer days of unhealthy ozone each year.

• Casper, WY and Urban Honolulu, HI share the top spot for cleanest year-round particle pollution.
• Other standout clean-air cities include Bozeman, Montana, Bangor, Maine and Colorado Springs, Colorado.

But even these wins feel dimmer to experts this year. In last year’s report, 55 cities had zero days with high ozone pollution. This year? Just 35. And only 22 cities had zero days with short-term particle pollution—down from 75.

So What Can Be Done?

The report makes it clear that solutions are within reach. Cities and states have powerful tools at their disposal, like investing in electric vehicle charging infrastructure and requiring more electricity to come from clean sources such as wind, solar, geothermal, and tidal energy. Urban areas can be redesigned with "smart surfaces"—features like cool roofs, porous pavement, solar panels, and increased green spaces—that help lower neighborhood temperatures and reduce the combined health risks of air pollution and extreme heat.

(MORE: The Link Between Air Pollution And Diabetes)

Individuals also have an important role to play. The American Lung Association encourages everyone to check daily air quality forecasts and prepare for environmental disasters like wildfires, floods, and storms. Reducing emissions in daily life—whether by driving less, choosing energy-efficient appliances, or cutting down on home energy use—can also help protect your health and the health of your community.

Because in the end, clean air is a matter of life, breath, and well-being for millions of Americans, and the more you know, the more you can do to protect it.

Weather.com lead editor Jenn Jordan explores how weather and climate weave through our daily lives, shape our routines and leave lasting impacts on our communities.