California's Air Resources Board on Friday released long-awaited draft rules to clean up big-rig pollution that can aggravate asthma, cancer and heart disease.
The statewide rules, which are scheduled to take effect in 2010, would apply to more than 1 million heavy-duty diesel trucks, many of which transport merchandise from the ports of L.A. and Long Beach.
Diesel truck transport is the state's largest source of smog-forming nitrogen oxide emissions and toxic particulates.
Southern California ports recently banned the dirtiest older trucks. But the San Joaquin Valley and Los Angeles areas are violating federal air quality standards, which cannot be met without stricter overall truck emission rules, air officials say.
Truckers and agribusiness interests have tried to soften the regulations, saying it is too expensive for truckers to invest in clean vehicles at a time of economic woes.