A new report says 40 percent of Americans live in counties with unhealthy levels of particle air pollution.
The annual “State of the Air” report, released Wednesday by the American Lung Association, also found that six of the 10 cities with the worst air pollution were in California.
The report found that 125 million Americans experience unhealthy levels of pollution, which has been linked to lung cancer, asthma and cardiovascular damage.
"While most of the nation has much cleaner air quality than even a decade ago, many cities reported their highest number of unhealthy days since the report began [18 years ago]," the report read.
The 10 worst cities for short-term particle air pollution were Bakersfield, Calif., Visalia-Porterville-Hanford, Calif., Fresno-Madera, Calif., Modesto-Merced, Calif., Fairbanks, Ala., San Jose-San Francisco-Oakland, Calif., Salt Lake City-Provo-Orem, Utah, Logan, Utah-Idaho, Los Angeles-Long Beach, Calif. and Reno-Carson City-Fernley, Nev.
California’s air quality issues are a result of a growing population and its numerous valleys that allow polluted air to settle, the report said. The high number of sunny days in Southern California also boost ozone levels, the report said, adding that the state would be in worse shape were it not for strict auto emission regulations as well as limiting coal-fired power plants.
The cities with the worst year-round particle air pollution were Visalia-Porterville-Hanford, Calif., Bakersfield, Calif., Fresno-Madera, Calif., San Jose-San Francisco-Oakland, Calif., Los Angeles-Long Beach, Calif., Modesto-Merced, Calif., El Centro, Calif., Pittsburgh-New Castle-Weirton, Pa.-Ohio-W.Va., Cleveland-Akron-Canton, Ohio and San Luis Obispo-Paso Robles-Arroyo Grande, Calif.
Just six cities recorded no days of unhealthy levels of pollution: Burlington, Vt.; Honolulu; Wilmington, N.C.; Fort Myers / Naples, Fla.; Melbourne, Fla., and Elmira, N.Y.
The report said that year-round levels of air pollution have improved, but shorter term spikes of very polluted air have risen.
"Even with continued improvement, too many people in the United States live where the air is unhealthy for them to breathe," the report said.
The report used data from states, cities, counties, tribes and federal agencies from 2013 to 2015.