New research shows a nearly threefold reduction in exposure to particulate pollution, but Californians living in overburdened communities re
Excerpt from this story from Inside Climate News:
California has long had more cars on the road than any other state. As its population exploded in the first half of the 20th century, so did the number of drivers, particularly in Los Angeles. By the 1940s, exhaust from millions of cars, fumes from power plants and a booming oil industry shrouded the famously sunny city in a noxious brown haze that left Angelenos wearing gas masks on days they couldn’t see more than three blocks.
A chemist identified automobile exhaust as the major source of the smog that regularly darkened city skies, laying the groundwork for California to pass the nation’s first tailpipe emissions standards in 1966.
The state has continued to implement the most aggressive air pollution policies in the country. But even as they cut exposure to one of the deadliest components in vehicle exhaust by nearly three-fold statewide over two decades, exposure disparities persisted or increased for people of color and residents of overburdened communities, a new study reports.
California environmental and climate policy has long focused on reducing air pollution for everybody because that clearly has big health benefits, said Joshua Apte, an air quality engineering expert at the University of California, Berkeley, who led the study, published in the peer-reviewed journal Science Advances. Apte and his colleagues wanted to know if state policies designed to address climate change and improve public health in California also reduced air pollution exposure disparities.
The team focused on pollution from vehicles, the largest source of greenhouse gases in California and the primary source of fine particulate matter, or PM2.5, which kills an average of 5,400 residents a year, according to the California Air Resources Board, or CARB. Vehicles release PM2.5 directly from tailpipes and indirectly when byproducts of gasoline combustion form particles through chemical reactions in the atmosphere.
To track the disparate exposures to PM2.5 across a state with nearly 36 million registered vehicles, Apte forged a unique partnership with two agencies under California’s Environmental Protection Agency, CARB and the Office of Environmental Health Hazard Assessment, or OEHHA. CARB provided estimates of mobile emissions by year and vehicle type from 2000 to 2019 at a fine geographic scale. Three scientists from OEHHA, which funded the work, collaborated on the study design and data analysis.
The team used CARB models to track both direct particle emissions and the gases that form atmospheric particle pollution. To understand how cars, light trucks and heavy-duty vehicles contribute to PM2.5 exposures across the landscape, they created a user-friendly tool called ECHO-AIR.
California’s aggressive policies to control vehicle emissions reaped across-the-board benefits, the team found, reducing PM2.5 emissions by 65 percent. Groups that have historically lived near the worst PM2.5 pollution saw the biggest declines in absolute terms, Apte said. But as exposures continued to drop for white residents, disparities in exposure rates held steady or increased for Hispanic, Black and Asian Californians and for residents of “overburdened communities,” where people are disproportionately affected by hazardous pollutants.
The 65 percent decrease from the transportation sector is a “big public health win,” said Alvaro Alvarado, chief of OEHHA’s Community and Environmental Epidemiology Research Branch and a study coauthor. “But the challenge remains that the most polluted are still the most polluted.”
