Despite only making up 7 percent of vehicles on the road in California, diesel trucks account for 70 percent of the state’s smog-causing pollution and 80 percent of diesel soot emitted. In a move that’s expected to shake the auto industry, the Golden State recently enacted one of the country’s most comprehensive rules targeting air pollution caused by transportation.

California’s Air Resource Board has introduced a new rule that says all commercial trucks and vans sold in the state in 2045 must be emission-free. The move would see a massive shift from dirty and harmful diesel-powered trucks to ones running on batteries and zero-emission hydrogen fuel cells.

It’s the first rule of its kind in the United States, and it follows California’s 2018 decision to mandate that transit agencies purchase all-electric buses starting in 2029, as well as its long-standing Zero Emission Vehicle program for passenger cars and trucks.

The rule is expected to go into effect as early as 2024, starting with smaller commercial vehicles. Half of all trucks sold in the state must be zero-emission by 2035, together with all short-haul drayage vehicles in ports and rail yards, while all last-mile delivery trucks and vans must be switched over by 2040.

Thanks to its role as a standard-bearer for clean air regulations, California’s new rule could have much broader consequences for the national transition towards greener transportation.

The regulation also represents a step forward in the fight for environmental justice, as the air pollution generated by delivery hubs and ports disproportionately harms California’s Black, Asian, and Latinx communities.