Los Angeles has again topped a list of the cities with the worst smog in the nation, violating federal health standards for ozone an average of 122 days a year.
The annual air pollution rankings, being released Wednesday by the American Lung Assn., were dominated by the Los Angeles Basin and California's Central Valley, which despite vast improvements over the last few decades still have the nation's highest levels of ozone and fine particle pollution.
"Air pollution is not just a nuisance or the haze we see on the horizon; it's literally putting our health in danger," said Bonnie Holmes-Gen, senior policy director of the American Lung Assn. in California. "We've come a long way, but the status quo is not acceptable."
The report evaluated metropolitan areas based on recorded levels of ozone, the main ingredient in smog, and conducted a separate analysis of fine particles — or soot — the microscopic pollutants that tend to build up in colder, winter months.
The Los Angeles region ranked fourth among metropolitan areas nationwide for short-term spikes in fine particle pollution, coming in behind Fresno, Visalia and Bakersfield. The L.A. Basin tied for third with Bakersfield for annual fine particle concentrations.
The nonprofit advocacy group's "State of the Air" report derives its rankings from publicly reported measurements of ozone and fine particle pollution from official monitoring sites. Analysts used data from 2010, 2011 and 2012 and...