California Tops the Nation in Cities with the Most Air Pollution

California’s Pollution Rankings in Latest Report

California is often celebrated for its stunning landscapes, yet it finds itself among the most polluted areas in the nation.

This information comes from the American Lung Association’s “State of the Air” study for 2026. The report assesses metropolitan regions using three main indicators: ozone pollution, short-term spikes in particle pollution, and annual particle pollution levels.

In fact, five cities in California made the top 10 for “Annual Particle Pollution,” and these areas also scored poorly in ozone levels and short-term particle pollution.

Overall, eight cities from the state fall within the top 25 most polluted cities across the United States.

Bakersfield, along with the Delano area, retains the title of the most polluted region among the 211 metropolitan areas for year-round particle pollution.

Additionally, four other areas in California are included in the top 10 for annual particulate pollution. Fresno ranks fourth, while Hanford and Corcoran share this spot. The San Diego region, along with Chula Vista, Carlsbad, and Visalia, is in fifth place, and Los Angeles alongside Long Beach occupies the seventh position.

The Bay Area cities, such as San Francisco, Oakland, and San Jose, are tied for 13th place, with El Centro coming in at 21st for ongoing particle pollution.

When looking at short-term particle pollution, Bakersfield moved from the number one spot last year to third this year, with Fairbanks, Alaska now taking the top position.

Los Angeles continues to be ranked first out of 226 metropolitan areas in terms of ozone production. This fact raises some questions, as it has held this position for 26 of the past 27 years.

The report highlights that ground-level ozone, commonly recognized as smog, is one of the most prevalent pollutants in the United States. Researchers have investigated how ozone impacts human health for many years, with numerous studies confirming its harmful effects at the levels found in various regions across the country.

Extensive research has made it clear that both particle pollution and ozone present serious health risks throughout life, including increasing the chances of premature births, exacerbating heart and lung diseases, and potentially shortening lifespans. Some populations are particularly vulnerable due to various factors, which can make them more likely to suffer from ozone-related health issues.

The report also notes that about 44 percent of Americans, totaling approximately 152.3 million people, reside in areas receiving poor ratings for levels of ozone and particulate pollution.

Additionally, nearly half of American children, around 46 percent or 33.5 million kids under 18, live in regions where they receive failing scores on at least one of the three indicators assessed.