And, while the goal is to cut back on toxic emissions, in today's economy that idea has truckers worried.
The black diesel soot often seen on the state's roadways could soon vanish into thin air if state regulators vote this week to impose strict new guidelines on the one million heavy-duty diesel-burning trucks on California's roads.
The rules would require truckers to either gradually replace the rigs, or install costly emission-catching traps by 2010.
Environmentalists are cheering. Truck owners are not.
"The price tag for our fleet to comply with this new ARB regulation is going to be $3 million," said
Bob Ramorino runs a Hayward trucking company and is President of the California Trucking Association. He says trucking company owners could be forced out of business.
Out-of-state trucks that deliver goods to California would also have to comply, so would school buses and even blood bank bloodmobiles.
Air Board spokesman Leo Kay says regulators are sympathetic to the trucking industry's financial challenges.
"Nobody's going to have to spend a dime until 2010. And, if we're still in dire economic straights at that time, we reserve the right to reassess the situation," he said.
Backers say the change could cut emissions that contribute to California's smoggy skies by 23 percent, by 2020.
Dr. John Balmes is a cardiologist at San Francisco General Hospital and an Air Resources Board member. He released the results Monday of the latest study to show alarming mortality and cancer rates among people who work around diesel engines.
"Those particles lodge into the deep lung and can irritate the airways," he said.
Truck owners are eligible for about $1 billion in grant funding from the state to pay for all the upgrades. But, that amount only covers about one-in-five trucks that are currently on the road in California.