> Foothill Transit will be first to operate hydrogen fuel-cell buses in the county, starting with three buses, then growing to 33 next year.

> The first hydrogen-powered public bus in Los Angeles County will go into service early next month, a historic milestone that will unleash an army of similar, zero-emission buses that don’t connect to the power grid and run longer without refueling.

> These will replace some older battery electric plug-in buses that are also zero-emission. But some will replace buses that run on Compressed Natural Gas (CNG), a fuel much cleaner than diesel but one that still produces greenhouse gases (GHGs) that contribute to climate change.

> One hydrogen bus will eliminate the 3,655 grams of carbon dioxide emitted per mile by a CNG bus, said Roland Cordero, director of maintenance and diesel technology for Foothill Transit.

> Each bus costs about $1.2 million, Cordero said. That’s slightly more than a battery-electric bus at $950,000, he added.