Report reveals most polluted US cities. Here's a full list

The United States is experiencing growing pollution issues because of wildfires, while factory and vehicle emissions decrease.

The American Lung Association’s ‘State of the Air’ 2025 report reveals that 156 million Americans in nearly half the nation experience breathing “unhealthy” air.

West Coast is marred by poor AQI

The ALA assessment investigated pollution data spanning 2021 to 2023, where it examined ground-level ozone, also known as smog, together with year-round particle pollution and short-term spikes of particle pollution.

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Bakersfield-Delano in California leads as the American city with the most severe persistent particle contamination, with Visalia and Fresno-Hanford-Corcoran in the same region occupy the second and third spots.

Detroit, Michigan, Eugene, Oregon, and Houston, Texas also made the list.

“This year's report shows the dramatic impact that air pollution has on a growing number of people,” Harold Wimmer, the president and CEO of the ALA told Newsweek in a statement.

“Even as more people are breathing unhealthy air, the federal staff, programs and policies that are supposed to be cleaning up pollution are facing rollbacks, restructuring and funding challenges.”

Here are the most polluted cities in the US:

Bakersfield-Delano, CA

Visalia, CA

Fresno-Hanford-Corcoran, CA

Eugene-Springfield, OR

Los Angeles-Long Beach, CA

Detroit-Warren-Ann Arbor, MI

San Jose-San Francisco-Oakland, CA

Houston-Pasadena, TX

Cleveland-Akron-Canton, OH

Fairbanks-College, AK

Indianapolis-Carmel-Muncie, IN

Pittsburgh-Weirton-Steubenville, PA-OH-WV

Chicago-Naperville, IL-IN-WI

Cincinnati-Wilmington, OH-KY-IN

Sacramento-Roseville, CA

Brownsville-Harlingen-Raymondville, TX

Medford-Grants Pass, OR

Missoula, MT

St. Louis-St. Charles-Farmington, MO-IL

Kalamazoo-Battle Creek-Portage, MI

Phoenix-Mesa, AZ

Texarkana, TX-AR

El Centro, CA

Yakima, WA

Spokane-Spokane Valley-Coeur d'Alene, WA-ID

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“Air pollution levels are influenced by a number of factors including population, geography, and typical weather. The more people you have in an area, you typically have more emissions, and therefore higher levels of air pollution,” Peter DeCarlo, a professor of environmental health and engineering at the John Hopkins Whiting School of Engineering told Newsweek.

“California has all of the ingredients to produce higher levels of air pollution: high population, mountains and the central valley, and sunshine and warmth.”