There’s something in the air — more in some places than in others, apparently.
In its 2025 State of the Air report, the American Lung Association identifies the cities in the United States with the least and most polluted air, using data from the U.S. Environmental Protection Agency.
To reach its findings, the report analyzed cities based on measurements taken over a three-year period, from 2021 to 2023, and examined the levels of particle and ozone pollution in American metropolitan areas.
Along with the release of its report, the ALA pointed out some startling air quality facts:
- Particle pollution can increase the risk of lung cancer.
- About half of Americans live where the air gets an “F” grade.
- Pollution is linked to an increased risk of premature birth and lower birth weight in newborns.
- Particles can be smaller than 1/30th of the diameter of a human hair.
For our snapshot of the State of the Air report, we’ll go the optimistic route and look at the metropolitan areas with the cleanest air in the U.S., as ranked for year-round particle pollution.
1. Casper, WY (tie)
This metropolitan area’s population: 79,941
While Casper ties for the healthiest air when it come to year-round particle pollution, its rankings for ozone and 24-hour particle pollution are slightly more mixed.
The ALA ranks Casper as 115th out of 228 metropolitan areas for high ozone days and 139th out of 225 metropolitan areas for 24-hour particle pollution. (Cities with rankings closer to No. 1 have the worst pollution for those rankings.)
The ALA describes ozone pollution as one of “the most dangerous and pervasive air pollutants nationwide.” Casper had only about one full high ozone pollution day per year between 2021 and 2023, on average.
1. Urban Honolulu, HI (tie)
This metropolitan area’s population: 989,408
The ALA ranks Urban Honolulu as 194th for high ozone days out of 228 U.S. metropolitan areas, which means the city is one of the cleaner cities when it comes to ozone pollution.
The number of high particle pollution days here has dropped significantly over the last couple of decades, with the metro on average going without a full 24 hours per year of high pollution between 2021 and 2023.
3. Kahului-Wailuku-Lahaina, HI
This metropolitan area’s population: 164,264
The ALA ranks Kahului-Wailuku, Hawaii, as 206th out of 208 metropolitan areas for annual particle pollution, making it one of the cleanest cities in this ranking.
And between 2021 and 2023, it didn’t have a single full day of high particle pollution days, on average.
The rest of the top 25
The following cities are great for anyone hoping to keep their lungs clear, as ranked for their year-round particle pollution by the ALA.
- Bozeman, MT
- Bangor, ME
- St. George, UT
- Anchorage, AK
- Cheyenne, WY
- Colorado Springs, CO
- Grand Junction, CO
- Wilmington, NC
- Lubbock-Plainview, TX
- Elmira-Corning, NY
- Salinas, CA
- Duluth-Grand Rapids, MN-WI
- Gainesville-Lake City, FL
- Amarillo-Borger, TX
- Syracuse-Auburn, NY
- Santa Rosa-Petaluma, CA
- Asheville-Waynesville-Brevard, NC
- Burlington-South Burlington-Barre, VT
- Pittsfield, MA
- San Juan-Bayamón, PR
- Portland-Vancouver-Salem, OR-WA
- Lynchburg, VA
Add a Comment