A gas leak outside of Los Angeles, in Aliso Canyon, last October forced more than 4,600 households into temporary housing and took 112 days to plug. Now, researchers say it may have been the worst methane leak in US history.

Overall, the Aliso Canyon gas leak released more than 100,000 tons of methane, according to a study published today in Science.That’s equivalent to the total annual emissions from 572,000 passenger cars. Air samples collected in the area also contained above-normal levels of benzene, a known carcinogen, and other potentially dangerous compounds. Given that methane is a dangerous greenhouse gas, more than 50 times more potent than carbon dioxide, leaks like the one at Aliso Canyon could end up having a significant climate impact, researchers say.

"I really hope now for greater oversight."

The disaster has drawn attention to the broader issues associated with natural gas production: rogue emissions, crumbling infrastructure and lax regulations. "I really hope now for greater oversight," says Stephen Conley, an atmospheric scientist at the University of California, Davis and co-author of the study. Instead of relying on information released from companies like SoCal Gas — the company that owns the ruptured well — independent researchers provide fast and accurate information to regulators and the general public during major chemical releases, the researchers say.

"We should be flying around the country at all the oil and gas fields — everywhere there is a storage facility — and measuring these things and seeing what their leak rates are and then tracking them," Conley says. An advanced warning system could help scientists avoid other catastrophic failures.