A new report shows Californian's breathe some of the nation's most polluted air. And climate change "is a growing threat to air quality in California."
The American Lung Association "State of the Air 2016" report used data from 2012 through 2014 to measure ozone and particle pollution.
Both pollutants are linked to lung disease and respiratory illnesses, including asthma and bronchitis.
The report says California has the most polluted air in the country, with cities in the state dominating the annual list. But air quality is improving in many areas.
Los Angeles remains the metropolitan area with the worst ozone pollution in the country. But the city had its lowest average year-round particles, and fewest high-ozone and high-particle days since the first report was issued 16 years ago.
Air in the Sacramento region also improved since the first report was issued in 2000.
"Sacramento saw a 53 percent reduction in ozone days and actually saw a 76 percent reduction in unhealthy particle pollution days," says Bonnie Holmes-Gen, Senior Director, Air Quality and Climate Change with the American Lung Association in California.
Bakersfield is at the top for most-polluted for particle pollution, "thanks to worse year-round and short-term exposures."
Holmes-Gen says climate factors are also a concern, as wildfires and drought increase particle pollution.
"Climate change is worsening our air quality problems and it's slowing our progress toward healthy air and we can see that in the results from our report,” says Holmes-Gen. “During the last few years when we experienced drought in California, the measurements for particle pollution definitely shot up in many areas of the state."
The report says that "wildfires and drought, along with high use of wood-burning devices for heat, coupled with stagnant weather patterns that concentrated pollution in some areas, contributed to the extraordinarily high numbers of days with unhealthy particulate matter in 2012–2014."
The report gives failing grades to farm communities in the Central Valley. The San Joaquin Valley has long struggled with meeting federal air pollution standards and has worked to improve the air quality.
"The San Joaquin Valley particularly has challenges with being surrounded by mountains, with inversion layers and weather that traps pollution in the area, plus truck traffic, agricultural equipment and wood smoke … all these pollution sources combine to create health-damaging pollution and that pollution unfortunately can be trapped for weeks or months at a time," says Holmes-Gen.
Not all cities, in California and around the U.S. made progress in improving air quality.
"Seven cities saw their year-round levels increase over the previous report, including the two most polluted cities, Bakersfield, and Visalia– Porterville–Hanford, California," the report noted. "Others with worse year-round particle pollution were San Jose–San Francisco–Oakland; Harrisburg–York–Lebanon, PA; and Louisville, KY. None of those five cities met the national health standard."