AIR QUALITY IN the South Bay is worse than neighboring parts of the San Francisco Bay Area — and it hits underserved communities hardest.

According to data compiled by the Bay Area Air Quality Management District, ozone levels are consistently higher in the San Jose area because of traffic congestion, weather and topography. Local studies show air pollution causes health issues like asthma, and communities of color and low-income neighborhoods tend to see higher levels of pollution than wealthier, whiter neighborhoods due to their proximity to highways and industrial areas.

Since May, ozone levels in the Santa Clara Valley have been worse on average than any other region monitored by the district, out-smogging even the refinery-laden North Bay, which includes San Rafael and Vallejo. Levels are similar to the traffic-clogged Eastern Zone, which incorporates Fairfield, Livermore and San Ramon.

“The Santa Clara Valley has consistently worse air quality (compared to other zones),” said Richard Lam, a district meteorologist.

Conditions in the Santa Clara Valley are perfect for creating and trapping ozone, Lam told San José Spotlight. The valley’s warmth and sun turn traffic emissions into the smoggy gas, and the mountains bordering Santa Clara County trap it there.

Average ozone levels in the valley tend to remain below the federal Environmental Protection Agency’s safety threshold, and they’ve only spiked to unsafe levels three times this year in Santa Clara Valley. But local studies show long-term exposure to air pollution in congested areas like San Jose can cause significant health impacts.

Local studies show communities of color and low-income neighborhoods tend to see higher levels of pollution than wealthier, whiter neighborhoods.

In an air pollution study published in May, San Francisco-based tech company Aclima collected air quality data block-to-block across 5,000 square miles and 101 Bay Area cities.

Across the region, communities of color and low-income neighborhoods are often closer to congested highways and emission-spewing factories where air quality is worse, the study found. For instance, 81.2 percent of Santa Clara County residents of color live in areas with unsafe levels of nitrogen dioxide, a harmful gas found in fuel exhaust. Nearly 95 percent breathe harmful particles in their neighborhoods, the study found.

Nonprofit air monitor Sustainable Silicon Valley, which studies air pollution in East Palo Alto, found child asthma cases are 2.5 times higher than the national rate in the traffic-clogged city, which borders a freeway and sits at the west end of the Dumbarton Bridge.

“There are pockets in all these communities that have worse air pollution than others,” Sustainable Silicon Valley Chief Scientist Anthony Strawa told San José Spotlight. “I think that if you did the same kind of study (in San Jose) those values would hold.”

Strawa is doing just that. His organization recently launched an air quality study and community outreach program, installing air monitors at 10 East San Jose high schools and working with students to research air quality in those communities. The study is already collecting data.

Wildfire and ozone

Smoke can push ozone and other harmful pollutants to unsafe levels, and as California nears the supposed end of an ever-expanding wildfire season, experts have advised residents to be mindful of ozone and other pollutants in their neighborhoods.

“Ozone can damage and inflame the lining in our lungs similar to how sun causes a sunburn on our skin,” air district spokesperson Erin Demerritt told San José Spotlight, noting it’s particularly harmful to pregnant women, the elderly and young children who breathe more rapidly than adults.

When pollution levels get too high, the district issues spare the air alerts so residents know when to cut back on driving and other polluting activities. The best way to cut back on air pollutants is for local residents to drive gasoline-powered cars less and use public transportation more, Demerritt said.

Check current air pollution levels in your area.

Contact Brian Howey at or @SteelandBallast on Twitter.

This story originally appeared in San Jose Spotlight.

Brian Howey, San Jose Spotlight