BRIAN WATT: The Golden State is on sort of a green roll. Starting this morning, all diesel fuel sold in California must be so-called "clean diesel." It's a move regulators say will reduce lung cancer, asthma and bronchitis. From the Sustainability Desk, Sarah Gardner reports.

SARAH GARDNER: California clean air officials say this new diesel blend is as important as the introduction of unleaded gasoline a quarter century ago.

It contains 97 percent less sulfur and will sharply cut down on noxious emissions from trucks, buses and construction equipment.

Jerry Martin is with the California Air Resources Board.

JERRY MARTIN: Industry in the U.S. and the world really is dominated and run by diesel fuel so we can't ban it. But we try to do everything we possibly can to reduce its effect on public health.

A similar diesel mandate will be phased in nationally starting next month.

Diesel prices have been rising this past year, partly due to the switchover. In California this week diesel was selling for about $3.20 a gallon.

I'm Sarah Gardner for Marketplace.

Follow Sarah Gardner at @RadioGardner