By Sharon Bernstein
SACRAMENTO, Calif. (Reuters) - Despite years of progress, California cities have the worst smog and particulate air pollution in the nation, conditions made worse by the state's ongoing drought, a report shows.
The annual report by the American Lung Association comes as the state struggles to protect both water and air in the face of a prolonged, catastrophic drought that is entering its fourth year.
"Residents exposed to air pollution are at greater risk for lung cancer, asthma attacks, heart attacks and premature deaths," said Olivia Gertz, president of the American Lung Association in California.
Five California cities, including Los Angeles, Bakersfield and the state capital of Sacramento, led the nation in ozone pollution, commonly called smog, during the two-year period from 2011 to 2013, according to the report.
The worst cities for both seasonal and annual particle pollution - the soot and dust made worse by warm, dry conditions during the drought - were also in California, the report said.
More than 70 percent of California residents, about 28 million people, are exposed to unhealthy air during the year, the report said.
According to the report, the Los Angeles area led the nation in smog, while the Fresno-Madera area in the state's San Joaquin Valley breadbasket had the worst particulate pollution.
Nationwide, metropolitan areas with the worst smog included Los Angeles, Visalia, Bakersfield, Fresno and Sacramento in California, followed by Houston; Dallas-Ft. Worth; Modesto, California; Las Vegas and Phoenix, the report showed.
Despite the rankings, the report showed that overall California's air has improved since the organization began tracking pollutants in 2000.
The number of bad air days in the San Francisco Bay Area and San Diego, for example, dropped 80 percent between 2000 and 2013. Particle pollution also fell during the period, dropping 70 percent or more in the Los Angeles, San Francisco, Sacramento and San Diego areas.
As the drought has continued, pollution levels ticked up in the state. The conditions have made it more difficult to keep the air clear in the state's vast valleys, where geography and warm, dry weather combine to keep dirt, haze and pollutants close to the ground.
In the summer of 2014, California was out of compliance with federal ozone rules for 99 days in the San Joaquin Valley, up from 89 the year before. Sooty particulates, which cause brown haze in the late fall and winter, were up throughout the state last winter.
(Reporting by Sharon Bernstein; Editing by Eric Beech)