Thirteen states have joined forces with California to force diesel trucks and buses to meet tougher anti-pollution standards than those required by the federal government.
State air quality officials announced yesterday in Washington, D.C. that they will require heavy-duty diesel engines to meet stringent testing standards to cut nitrogen oxide emissions from exhaust between 2004 and 2007.

The states’ proposal would slash emissions from diesel trucks by 27 tons daily in California and New York alone and will include any heavy diesel engine manufactured during 2005 or later.
This is the first time states have used their authority to act independently of the federal government to reduce exhaust from heavy-duty diesel engines. Under federal law, states are allowed to take such action as long as they proceed along with California, which is the only state allowed to implement its own tougher air pollution requirements. The state is expected to adopt a model regulation targeting vehicles above 14,000 pounds when the California Air Resources Board meets Dec. 7-8.
"These new rules are needed to prevent diesel manufacturers from deliberately designing and building higher polluting trucks in those years than they will build between 2002 and 2004," California environmental secretary Winston Hickox told the Los Angeles Times.
Environmental officials believe these regulations are needed because of a gap in federal emissions regulations.
Seven engine manufacturers were accused of equipping more than 1 million vehicles with engines designed to override emission control systems between 1988 and 1998. They were eventually fined more than $83 million and under a consent decree between the manufacturers and the federal government, agreed to specific engine tests to ensure emission compliance during 2002-04.
Federal standards containing the NOx reduction requirements have been adopted for 2007 model year and later vehicles. However, because of Clean Air Act requirements, CARB claims, the U.S. EPA has been restricted from adopting heavy-duty emission standards for 2005 and 2006. Since the engine tests were adopted federally for the 2007 model year and later, air quality officials are afraid that the companies will be able to revert back to weaker requirements during the intervening years.
Richard Varenchik, spokesman for the California Air Resources Board, said the proposed ARB rule would prevent such an action.
"It’s something that we can’t afford backsliding on," he said.
Varenchik added that engine manufacturers have known about this move and that they shouldn’t be caught offguard.
"They knew we were thinking about it," he said.
Other states joining in support of California’s tougher standards are New York, New Jersey, Massachusetts, Connecticut, Rhode Island, New Hampshire, Vermont, Maine, Delaware, Georgia, North Carolina, Texas and Nevada.