Clean air strategy would further tighten restrictions - Aging truck fleets, wood-burning fireplaces and char broilers face changes if plan passes.

Air quality officials from Southern California and the state jointly announced a sweeping set of measures Friday aimed at improving Los Angeles' badly polluted air in time to meet a 2014 federal deadline.

Targeted for possible ban, retrofit or replacement are aging heavy-duty truck fleets, wood-burning fireplaces in homes and char broilers in restaurants.

Regulators are also seeking millions of dollars to retrofit Metrolink trains with anti-pollution devices, will ask the federal government to move more quickly on reducing emissions from locomotives, and will ask local governments in the four-county metropolitan area to use vehicle registration fees to replace municipal dump trucks and other diesel equipment.

The two agencies involved, the California Air Resources Board and the South Coast Air Quality Management District, "have rolled up their sleeves and worked together to turn over every possible stone" to get diesel soot and ozone smog to safe, legal levels, said Barry Wallerstein, executive officer of the South Coast district.

Echoed California air board chairwoman Mary Nichols: "This signals the dawn of a new day in cooperation . . . that will result in cleaner air."

The plan is scheduled to be voted on Thursday by the state air board and must also be approved by the U.S. Environmental Protection Agency.

It comes after almost two years of protracted wrangling between state and regional agency staff over how much air pollution needs to be cut by which agency.

Tim Carmichael of the Coalition for Clean Air said he was pleased with the plan as outlined, although he, like many others, noted that details remain to be worked out.

"I think this is good progress. . . . The bottom line is, we've had scientists telling us this for years: 'It's the trucks, stupid.' There's a huge amount of pollution that is coming from trucks."

But Julie Sauls of the California Trucking Assn. said Friday's announcement was the latest of a series of proposals aimed at an industry that contributes just 9% of the region's diesel emissions.

"We're a part of the problem, and we want to do our part, but we are not the only part," she said.

Requiring a large chunk of the 160,000 or more trucks on the road in Southern California to be as clean as brand-new 2007 trucks could cost companies billions of dollars to replace or retrofit equipment, she said, because diesel engines can last as long as three decades.