New study finds 65% decrease in California’s fine particle pollution over 20 years

A new study found a 65% decrease in California’s fine particle pollution from vehicles from 2000 to 2019. 

“This is a massive win for public health,” said Joshua Apte, a UC Berkeley researcher and an author of the report.

Fine particle pollution — also called PM 2.5 — can come from a variety of sources, including wildfire smoke and the combustion of gasoline, oil and diesel. Inhaling it has been linked to respiratory problems, premature death and a host of other health issues. 

California’s ability to set stricter vehicle emissions standards than the federal equivalent has allowed it to lead the nation in cutting back on this kind of pollution. It’s why the state can set ambitious goals, like phasing out the sale of new gas-powered vehicles by 2035. 

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But while fine particle pollution from vehicles decreased overall, the study found historically disadvantaged communities — often communities of color — still face disproportionate impacts. 

“Unfortunately, we see that those communities that were the most polluted 20 years ago are still the most polluted today,” said Alvaro Alvarado, a scientist with California’s Office of Environmental Health Hazard Assessment and a co-author of the report.

Apte said these communities have seen less fine particle pollution from vehicles overall, but the disparity over the years has remained the same. 

“Who lives closer to what pollution sources is a question of our infrastructure,” he said. “It's a question of urban planning and unfortunately, it's also a question of the racist legacy of how those two things have interacted in our society, often for a century or more.”

He added redlining and other examples of historical racism have made it so these communities still see higher rates of emissions.

“Overcoming those disparities is not something we can do in a year or maybe even a decade, but it's something that you have to chip away at slowly,” he said. 

The authors of the report suggested closing this gap will require focused efforts to reduce vehicle emissions in the places that are more heavily impacted. 

“We think about where … communities that have a high burden of air pollution are located,” said Alvarado. He said port communities, which often see emissions from heavy-duty diesel trucks, are one example of a place to focus on.