EPA Orders Cuts in Urban Bus Pollution : Environment: The limits on particulate emissions will apply to the 49 largest cities. There should be little impact on Southern California.

Declaring that the end is in sight for the smoke-belching urban bus, the Environmental Protection Agency announced plans Tuesday to cut the noxious emissions from diesel exhausts by about 90% in the nation’s major metropolitan areas.

Under the mandate of the 1990 Clean Air Act, the agency said that it will require new buses to reduce particulate emissions 86% below that of uncontrolled vehicles by 1993, and by 93% after 1994. In addition, urban transit systems will be required to begin retrofitting and rebuilding old engines to make their emissions comparable to those of new buses.

“We are taking action to lift the dark cloud that hangs over our nation’s bus fleet and to eliminate the most noxious source of urban air pollution in our cities,” said William G. Rosenberg, EPA’s assistant administrator for air and radiation, predicting that the program will “make smoky urban buses a thing of the past.”

With new clean-burning diesel fuel coming onto the market in 1993, Rosenberg said that fleets will be able to meet the 86% reduction with diesel engine equipment already available. But technology will be challenged to reach the 93% reduction, he said. Should the more stringent requirement be impossible to achieve, the EPA is empowered to order conversion to buses using clean-burning fuels, such as compressed natural gas, ethanol or methanol.

The regulations apply to the country’s 49 largest metropolitan areas, which operate about 35,000 buses transporting 80% of the nation’s urban bus riders.

They are not expected to have a major impact in Southern California, where air pollution controls are more stringent than federal requirements. The State Air Resources Board adopted requirements for the use of “clean” diesel fuel in 1988, and last January it put into effect the same standard that the EPA proposes to implement in 1993.

The Southern California Rapid Transit District, operator of the largest urban bus fleet in the nation, already has acquired 30 methanol-burning buses and several others that use the new “clean” fuel.

With its skyscraper canyons and heavy dependence on buses, New York City epitomizes the problems created by particulate emissions from diesel engines. But in Southern California’s four-county South Coast Air Basin, diesel engines are responsible for an estimated 10% to 20% of the area’s diminished visibility. By some estimates, as much as 8% of lung cancers among people who are not smokers result from diesel pollution.

Before 1988, there were no federal controls on diesel emissions but in the last three years, the EPA has required a reduction of about 40% from uncontrolled levels.

Rosenberg said Tuesday that the EPA expects the stringent standard for 1994 and beyond to create spirited competition between manufacturers of new high-tech diesel engines and producers of engines burning alternative fuels. One company, Detroit Diesel Corp., already has announced that it is prepared to sell a methanol-burning bus.

Still to be determined is the precise amount of reduction to be required of older buses that will be retrofitted.

The issue will be addressed in a public hearing at EPA’s Vehicle Emissions Laboratory in Ann Arbor, Mich., in October. The proposed standards are expected to go into effect in six to nine months.

Under the sweeping new clean air legislation passed by Congress last year, the EPA is required to put some 55 new sets of regulations in place by the end of next year. It has already initiated 35 of them.

Under regulations already in place, diesel-burning trucks will be required to meet the 86% reduction by 1994, a year after bus fleets. The clean diesel regulation adopted last year and scheduled to go into effect on Oct. 1, 1993, is expected to eliminate 196,000 tons of diesel particulate emissions each year by 1995.