California's done it again, with another groundbreaking action on climate and public health.

This time, the state became the nation's first to commit to a 100 percent zero-emission bus fleet. The decision came on Dec. 14, when the California Air Resources Board unanimously approved increasingly strong purchasing standards, ultimately requiring all public transit buses to emit zero carbon and zero lung-damaging pollutants by 2040.

"It makes no sense to continue to use buses that impact our climate and hurt our kids, especially when we can use clean electric buses," said Environment California State Director Dan Jacobson to the Desert Sun. "We want 100 percent clean buses and zero percent child asthma."

The board predicts that, when fully implemented, the plan will reduce carbon dioxide emissions by 19 million metric tons by 2050. That's the equivalent to taking 4 million cars off the road.

Photo: Los Angeles residents board a L.A. Metro bus in Echo Park. Credit:  Downtowngal via Wikimedia Commons CC BY-SA 3.0