Air Quality

Napa County, in contrast, scored an A for having zero unhealthy ozone (smog) days and a B for just one unhealthy particle day between 2014 and 2016.

Scores are based on a three-year rolling average, so the bad air from last October’s wildfires won’t appear in the scores until next year’s report, said Jenny Bard, director of Health Partnerships for the American Lung Association in California.

“We had air pollution levels similar to Beijing during the wildfires,” Bard said.

But in the latest report, “Napa has some of the cleanest air in the country,” said Bard. This is due to the prevailing winds that blow pollution generated in Napa and other Bay Area counties into the Central Valley, she said.

“Napa is fortunate to be an area of relatively clean air” compared to much of the state where serious air quality issues remain, Bard said.

Statewide, 35 million Californians — 90 percent of the population — live in counties affected by unhealthful air during the year, the American Lung Association reported.

Air pollution can cause asthma attacks, heart attacks, strokes, lung cancer and other health problems, the association said.

Cleaning-burning vehicles and restrictions on wood burning have improved Bay Area air, but high temperatures in 2016 — the second warmest year on record in the U.S. — boosted smog levels, according to the report.

“Federal and state policies like the Clean Air Act and strong California clean car standards are working. We are improving air quality, but the impacts of climate change are interfering with progress,” said Bonnie Holmes-Gen, senior director, Air Quality and Climate Change, American Lung Association in California.

“The reality is California still has unhealthy levels of air pollution in large areas of the state, which puts Californians at risk for premature death and other serious health effects such as asthma, COPD and lung cancer. We must continue the life-saving work of cutting air pollution and slowing climate change.”

The Bay Area ranks among the worst for particle pollution. The region, which includes San Joaquin County for this study, was ranked as the 6th most polluted for short-term particle pollution and tied for 10th for year-round particle pollution. However, the region did improve in both categories compared to last year’s report, which saw its highest reported levels to date.

San Joaquin and Santa Cruz County, by far the two worst counties for particle pollution in this extended region, saw significant improvements from peak pollution levels reported last year, but still earned F grades.

Long-term progress is being made. The Bay Area has experienced a nearly 70 percent drop in unhealthful ozone days since the 2000 report and an 80 percent drop in unhealthful particle pollution days since 2004.

California’s most populous metro area, Los Angeles, led the nation for ozone pollution, faring worse than it did in the 2017 report. The San Joaquin Valley dominated the list of most polluted for short-term and year-round particle pollution with Visalia, Bakersfield and Fresno all landing in the top five.

Learn more about California’s grades including local air quality data for each county and metropolitan area at www.stateoftheair.org/california2018.