Driving in Front on Diesel Control

Monday’s announcement that 13 other states will join California in imposing new measures to cut the soot spewed from diesel-powered trucks underscores this state’s leadership in the national air pollution fight. California has moved decisively since diesel exhaust was identified as a carcinogen and has been ahead of other states and the federal government in ordering reductions.

The 13 Sunbelt and Northeastern states are joining with California to plug a loophole created in 1998 when the U.S. Environmental Protection Agency and the Justice Department reached a settlement with seven diesel engine makers charged with intentionally underreporting their emissions under real driving conditions. The pact required that, until 2004, engines must perform nearly as cleanly on the road as under controlled test conditions. But between October 2004 and 2007, when new federal rules kick in, engine makers are not bound to meet this test, and air quality officials feared that emissions would shoot up in those three years.

At its Dec. 7 meeting, the California Air Resources Board is likely to extend those interim testing rules to trucks sold in the state until the federal rules take effect in 2007. The 13 other states have said they will do the same.

The move is important because the testing rules are really emissions controls. Tests that low-ball the amount of soot and other pollutants that diesel engines actually emit on the road are hardly helpful in producing cleaner air.

Since the California air board linked diesel exhaust to cancer in 1998, state and local air quality officials have taken giant steps to cut diesel pollution. Since last summer, for instance, the South Coast Air Quality Management District has ordered that new government-owned trucks and buses, except for school buses, must use alternative fuels. In September, the state air board mandated the use of low-sulfur diesel fuel statewide by 2006 and required that all diesel engines, whether new or already in service, have particulate traps to reduce emissions.

Federal law currently allows California to impose tougher air pollution requirements than the rest of the nation, and other states are now following our lead. This bodes well for cleaner skies.