SACRAMENTO - The California Air Resources Board (ARB) today announced that it has approved the first clean diesel fuel formula developed by an oil company that meets the state's tough anti-smog standards for 1993 and beyond.

Although the ARB already requires the nation's cleanest diesel fuel, the 1993 standards are expected to reduce soot-like emissions from existing trucks and buses by about 17 percent, as well as help engine manufacturers meet current tailpipe standards that require "sootless" new models.

The clean diesel fuel, produced by Chevron USA, is a different "recipe" than the specific formula adopted by the ARB in November 1988 that requires up to an 80 percent cut in sulfur as well as up to a 66 percent cut in aromatic hydrocarbons, a component of diesel fuel that is prone to forming soot-like particle emissions. Reducing aromatic hydrocarbons also cuts emissions of nitrogen oxides, which form acid rain and urban smog, as well as benzene and other highly toxic and potentially cancer-causing compounds.

Chevron USA chose to meet the new standards by taking advantage of a provision in the ARB's rules that allows alternative formulas, as long as they reduce the same amount of pollution. By juggling other components in the fuel, Chevron USA was able to be more flexible in using its refinery capacity and reduce its costs, producing an equally clean diesel fuel with greater cost-effectiveness. Refiners using an alternative formula must supply the ARB with test data documents that prove the blend meets emission standards.

"The ARB adopted a clean air "recipe' for diesel fuel because of the many health advantages it would provide and to be consistent with our demands for cleaner fuels of all types," said ARB Chairwoman Jananne Sharpless. "We wanted cleaner air, but we wanted to be flexible too," she said. "We gave the oil industry the opportunity to find an alternative way to produce the same results and Chevron has taken advantage of our rules to do just that. As a result, all of us who breathe the air, as well as those who buy diesel fuel will benefit."

Sharpless also noted that Chevron's development of a cleaner diesel fuel is encouraging, and said that the ARB expects many other oil companies to do the same, insuring an adequate supply of cleaner diesel fuel by the 1993 deadline. "Some oil companies are re-evaluating their place in the diesel market," she said, "and they may make individual decisions based on the status of their

"But as long as there is a market for diesel fuel, we are confident that there will be enough suppliers to meet the demand."

Besides reducing emissions from existing buses and trucks, the cleaner fuel will make it easier for manufacturers to meet strict tailpipe standards for particulate soot adopted by the ARB in 1996. Those standards cut emissions by 90 percent, requiring "smokeless" urban bus engines for 1992 and will also apply to new model trucks beginning with the 1994 models.