Regulators Approve Rules to Cut Diesel Soot 75% Over 10 Years

State air regulators approved a plan Thursday to cut soot from diesel engines 75% over the next decade, using the toughest rules in the nation. The new rules will require state-of-the-art filters on new diesel engines sold in California and the retrofitting of most existing engines.

Approval of the plan had been widely expected. The 10-0 vote by the state Air Resources Board also requires production of low-sulfur diesel fuel for engines equipped with the filters.

Diesel pollution contributes to problems ranging from reduced visibility to respiratory illnesses and increased risk of cancer, state officials say. The state estimates that 28,000 tons will be spewed into California’s air this year.

“It is certainly the No. 1 airborne toxic contaminant in California,” said Jerry Martin, a spokesman for the air board.

The proposal’s drafters hope to equip 90% of the state’s 1.2 million diesel-powered engines with filters, Martin said. Engines that are too old, one of a kind, in poor condition or altered so that retrofitting them will not be possible will be considered on a case-by-case basis, he said.

California is the only state with the power to adopt emissions controls tougher than federal standards. The diesel plan comes as the U.S. Environmental Protection Agency considers its own set of diesel pollution limits for new heavy-duty engines for trucks and buses.

Details of the California plan will be spelled out in a series of regulations that the board will act on over the next three years.