San Diego remains in top 10 for worst ozone pollution in the U.S.
Add Axios as your preferred source to
see more of our stories on Google.
Illustration: Annelise Capossela/Axios
San Diego's ozone pollution is among the worst in the U.S., making it one of the smoggiest areas in the country, according to a new report from the American Lung Association.
Why it matters: Air pollution threatens everyone's health — especially children, older people and those with asthma or heart and lung conditions.
Zoom in: San Diego-Chula Vista-Carlsbad region ranked No. 8 among the 25 U.S. metro areas most polluted by ozone, per the ALA's 2025 State of the Air report.
- The area, which covers the county, received an "F" grade for the number of days with high ozone and a failing grade for year-round particle pollution.
Yes, but: San Diego's air quality is improving by some measures, dropping off the 2025 list of the 25 most polluted U.S. cities for daily particle pollution.
How it works: The report uses local air quality data to grade and rank locations based on ozone pollution, daily particle pollution and annual particle pollution.
- This latest report includes data from 2021 to 2023, "the most recent three years of quality-assured nationwide air pollution data publicly available."
- Ozone is a gas that, at ground level, is a harmful irritant often created from vehicle emissions. Particle pollution involves tiny airborne particles from wildfires, fossil fuel burning and more.
State of play: More counties improved than worsened in California in terms of ozone pollution, but the state has the most metro areas on the list with nine of the 25 most-polluted cities, per the report.
- Nearly 90% of Californians live in an area with at least one failing grade, and 14 counties received failing grades for all three measures of pollution.
- Los Angeles remains the worst area in the country for smog, followed by Visalia and Bakersfield, California.
- Salinas, Santa Rosa-Petaluma, San Luis Obispo and Santa Barbara were on "Cleanest Cities" lists.
The big picture: Nearly half of Americans are now exposed to potentially dangerous levels of air pollution, per the report.
- Extreme heat, wildfires and drought are degrading air quality nationwide, the Lung Association says. All have been linked to climate change.
Stunning stat: Hispanic people are almost three times more likely than white people to live somewhere with failing grades in all three categories.
Threat level: This pollution can cause premature death, asthma attacks, heart attacks and strokes, preterm births, impaired cognitive functioning later in life and lung cancer, according Mariela Ruacho, a senior manager for Clean Air Advocacy with ALA.
- California needs to "double-down on investments to reduce wildfire risk, spur zero- emission transportation and energy sources, and align transportation funding with pollution reduction needs," she said in a statement.
Between the lines: The findings, which predate the current Trump administration, come as the White House is reconsidering EPA rules and regulations meant to curb pollution and promote cleaner air.
What they're saying: "Clearly, we need to do more to control the pollutants that are impacting our changing climate and worsening the factors that go into the wildfires and the extreme heat events that are threatening our health, instead of thinking about how to roll them back," said report author Katherine Pruitt, senior director of nationwide clean air policy at the ALA.
The intrigue: Join the LUNG FORCE walk on June 8 at Liberty Station to support the ALA's fight against lung cancer and lung disease.