


California cities make up the majority of the nation’s most polluted cities, according to a recent report by the American Lung Association.
The association’s 2023 State of the Air report (pdf), published April 19, lists several of the state’s cities in the top 10 for most polluted in three categories.
Los Angeles remains the city with the worst ozone—or smog—pollution in the nation. The city has held the title for all but one of the 24 years tracked by the association.
Chico, Calif., improved its air quality enough to move off the list of most smog-polluted cities.
Ten of the Golden State’s counties received failing grades for all types of pollution—Fresno, Kern, Kings, Los Angeles, Madera, Riverside, San Bernardino, Stanislaus, Sutter, and Tulare.
The five California cities most polluted by daily particulate matter—such as dust, dirt, or smoke—are:
The five California cities most polluted by annual particulate matter are:
The five California cities most polluted by ozone are:
Nationally, seven cities were ranked as the cleanest cities for particle pollution and ozone. The cleanest cities are: