Southern California, home to some of the dirtiest air in the nation, is dumping diesel engines in favor of cleaner-burning energy sources such as natural gas and electricity.
Last year, a report conducted by the South Coast Air Quality Management District, a local air pollution control agency, found that diesel exhaust is responsible for 70 percent of the potential carcinogens in local air pollution. In June, the district unanimously passed three rules targeting a reduction in diesel emissions.
The new rules focus on the gradual replacement of diesel fleets operated by public agencies. As old garbage trucks and public buses wear out, agencies will purchase nondiesel models. During this process, private contractors will build new fueling stations for natural gas and electric vehicles.
While this is a step in the right direction, Bill Kelly of the district says, existing diesel fuel also needs improvement, since hundreds of thousands of diesel vehicles will continue running for several years. "The average school bus is anywhere from 10 to 20 years old," he says. "Only a handful are going to be replaced each year." This month, the district will review a rule that would require public agencies to purchase low-sulfur diesel.
While environmentalists laud California's efforts, they are also pushing to reduce diesel emissions in privately owned vehicles. Julie Masters of the Natural Resources Defense Council says public fleets should be taking the lead in diesel reduction, but private trucking companies should follow their examples. The council recently won a lawsuit against several supermarket chains in California, a decision that requires the companies to purchase 150 alternative-fuel vehicles.