LA's air quality is dismal and the Bay Area isn't much better, according to report

The air quality in San Francisco has reached the purple on the Air Quality Index (AQI) as the skyline is shrouded in smoke from the Camp Fire on Friday, Nov. 16, 2018 in San Francisco, Calif. The air quality in San Francisco has reached the purple on the Air Quality Index (AQI) as the skyline is shrouded in smoke from the Camp Fire on Friday, Nov. 16, 2018 in San Francisco, Calif. Photo: Russell Yip, The Chronicle Buy photo Photo: Russell Yip, The Chronicle Image 1 of / 18 Caption Close LA's air quality is dismal and the Bay Area isn't much better, according to report 1 / 18 Back to Gallery

The air quality in California is dismal and wildfires have significantly worsened the air Bay Area residents breathe, according to a new report by the American Lung Association.

"Unfortunately, California continues to have the most cities on the list of most polluted cities," says Jenny Bard, the director of health partnerships for the association. "California has historically dominated these lists every year. We have the severe challenge of millions and millions of people driving millions of miles and now we're seeing the impacts of climate change."

While vehicles remains the leading cause of air pollution, the "State of the Air 2019" report says climate change, which is driving temperatures higher and fueling wildfires, is exacerbating the problem.

"For the first time, not a single Bay Area County earned an 'A' for short-term particle pollution," says Bard. "In 2017, there were 9,000 wildfires alone in California, and there were some very significant large ones like the North Bay fire."

ALSO: This is where air quality was the worst in the Bay Area in 2018

The report used data from official monitoring sites in 2015, 2016 and 2017 to rank cities in three areas: number of high-ozone days in the year, year-round particle pollution levels, and the number of days with 24-hour spikes in particle pollution.

In all three measures, California cities ranked as the most polluted in the country. Bard calls the results "alarming."

The Los Angeles metro area continues to have the the worst ozone pollution in the nation, as it has for 19 of the report's 20-year history. Fresno-Madera-Hanford returned to the most-polluted slot for year-round particle pollution, while the Bakersfield area maintains its rank as the city with the worst 24-hour spikes in particle pollution.

The report lumps together the Bay Area with neighboring counties including San Joaquin, Santa Cruz, San Benito, Merced and Stanislaus. The large region was the eighth worst for ozone pollution, sixth for year-round particle pollution, and fourth for short-term particle pollution in the country.

Tail pipe exhaust from cars combined with heat form ground-level ozone, also known as smog. The warmer the temperatures, the more likely ozone is to form. The report covered 2015 through 2017, which were the three hottest years on record in the United States, setting the stage for widespread ozone increases.

While ozone levels have declined 78 percent among the nine Bay Area counties in the past 20 years, they inched back up between 2015 and 2017.

"Ozone levels would likely have been worse with the hot temperatures if not for the higher number of clean air vehicles on Bay Area roads," says Kristine Roselius, a spokesperson for the Bay Area Air Quality Management District.

Wood burning fireplaces, wildfires and diesel engines pump unhealthy particles into the air. "Technically known as PM2.5, these microscopic particles lodge deep in the lungs and can enter the bloodstream, triggering asthma attacks, heart attacks and strokes, and can cause lung cancer," according to the American Lung Association.