Out of the California cities that ranked the worst for ozone and particle pollution in 2025, the Fresno and Sacramento metropolitan areas improved the most compared to 2024, according to the American Lung Association. The Fresno-Hanford-Corcoran metro area dropped one place after ranking No. 4 for ozone pollution in 2024.

The LA area is once again the worst for ozone in the U.S., a pollutant impacting millions more people nationwide, the American Lung Association said.

The most recent State of the Air report by the American Lung Association found that more than 150 million Americans breathe air with unhealthy levels of ozone or particle pollution