By City News Service Apr 21, 2021 LOS ANGELES (CNS) - The Los Angeles-Long Beach metropolitan area again ranked as the most ozone-polluted region in the nation, joining six other California areas on the list of the 10 worst cities for ozone in the United States, according to an American Lung Association report released today. Los Angeles has topped the ozone-pollution list for 21 of the 22 years the Lung Association has produced the “State of the Air'' report. The San Diego-Chula Vista-Carlsbad region ranked seventh on this year's list. Los Angeles-Long Beach ranked sixth on the list of cities with the worst short-term particle pollution, and fourth for year-round particle pollution.