Some of Central Valley’s air pollution imported from Asia
March 31, 2015
• About 10 percent of it drifts in from thousands of miles away
• “We're going to have to treat air pollution to some extent how we treat greenhouse gases”
About 10 percent of ozone pollution in the San Joaquin Valley is coming from outside of California, particularly from Asia, according to preliminary research presented Tuesday by the University of California, Davis.
UC Davis atmospheric scientist Ian Faloona shared his research – paid for by the San Joaquin Valley Air Quality Control District -- with air quality regulators and scientists at a transboundary pollution conference near Yosemite National Park.
"To me, it's an exciting new chapter of how we think of air pollution," says Mr. Faloona. "How do we deal with this not just as an air district of a couple of counties, but as a nation and a global citizen of the planet? Traditionally, air pollution has always been considered an issue to be handled locally. But we're going to have to treat air pollution to some extent how we treat greenhouse gases."
Scientists have long known that a portion of ozone pollution was coming from overseas, but attempts to quantify just how much were hamstrung by coarse computer models that overlooked or broadly simplified California's complex terrain.
Mr. Faloona describes California as if it were a human body: The Golden Gate bridge is the mouth, breathing in air from across the Pacific Ocean, sucking it through the throat of the Bay Area and into the lungs of the San Joaquin Valley.
Previously unknown is how much air comes over the coastal mountain range and mixes from above into the bathtub that is the San Joaquin Valley.
UC Davis researchers have spent the past three years trying to measure that contribution from a mountaintop air quality monitoring station near California's Point Sur. They've also gathered it from a plane equipped with scientific instruments that measure air pollutant levels -- a flying air monitoring station of sorts. The combined data has allowed them to analyze the "signature" of the sources and quantify how much of the valley's ozone pollution is locally produced, and how much is drifting across from international sources.
The research comes as the U.S. Environmental Protection Agency has proposed tightening ozone limits from 75 parts per billion to between 65 and 70 parts per billion later this year. In the San Joaquin Valley, which includes the cities of Fresno, Stockton and Bakersfield, such a change by the EPA is expected to push much of the valley further out of compliance.
Air districts are financially penalized and considered out of compliance for going over federal ozone pollution thresholds, known as National Ambient Air Quality Standards.
"In addressing the tremendous public health challenge we face in reducing ozone, it is critical to accurately identify the sources of ozone pollution so that solutions can be appropriately targeted," says Seyed Sadredin, executive director of the San Joaquin Valley Air Pollution Control District. "The scientific information being discussed at the transboundary ozone conference will be invaluable to many regions throughout the nation."
Mr. Faloona notes that the majority of the air pollution in California is coming from local sources, which requires further work. He says his research is not about pointing fingers but about having a clearer picture of where pollution comes from -- and how a global community can help reduce it.