With diesel gone, air better

Apte, a professor of civil and environmental engineering at University of California, Berkeley, along with his colleagues, found that electrification reduced exposure to black carbon, a known carcinogen, by 89%. According to a UC Berkeley report, the black carbon reductions from electrification “cut excess cancer deaths by 51 per 1 million people for riders and 330 per 1 million people for train conductors.” According to policy for the U.S. Environmental Protection Agency, “any exposure that increases the average individual’s cancer risk by more than one per million is considered unacceptable.”

Black carbon levels were particularly elevated at the San Francisco Caltrain station, where the locomotives are stored. Apte said that even when stationary, diesel trains continued running for hours, emitting excess pollution.

“If you shut off the locomotives in between trips, they have to do all these safety checks when they turn them back on again, and they don’t have the staff to do that, so the only thing they’re able to do is leave the locomotives idling basically 24/7,” he said.

The first car on the trains also showed high levels of pollution, especially for southbound trains, as the part of the car designed to take in fresh air ended up consuming diesel fumes, creating pollution levels “nearly as bad as the levels of air pollution in New Delhi,” he added.

“Southbound trains had these extreme levels of black carbon,” Apte said. “There was an excess cancer risk for someone who works on the trains, like a conductor, that is way above what is legally allowed in California.”

The electrification effort cost about $2 billion, with the project receiving about $500 million in funds from the state’s cap-and-trade program. The agency is the largest commuter rail operator in the western United States, though there are other commuter rail agencies throughout the state still running on diesel. With federal funding for climate change-related initiatives remains precarious, continued investment in the state’s program could help offset potential loss at the national level, Apte said.

Dan Lieberman, spokesperson for Caltrain, said that clean air is “one of the many benefits of our newly electrified service.”