The auto maker will spend $2.5 million to reduce emissions in diesel school buses, research natural-gas driven trains and put alternative-fuel vehicles on the road.

Officials with GM and the Los Angeles air-quality district said the plan attacks several air-pollution sources and will encourage other companies to team up with a district they have often considered an adversary. "I'm already getting calls from other companies that want to step up to the plate," said William Burke, chairman of the South Coast Air Quality Management District Governing Board. "When the biggest corporation thinks it's appropriate to do it, others follow."

Mr. Burke said GM will equip 35 school buses with "particulate traps" designed to eliminate sooty particles in diesel exhaust that reduce visibility and lodge into lungs. Diesel engines, like those in most school buses, are in only about 2% of California vehicles, but a district study found they account for more than 70% of toxic substances in the air of the smog-plagued Los Angeles basin. One of every 1,000 cancer cases in the region can be attributed to diesel toxins, according to the study.

GM also will contribute material and expertise toward the development of a natural-gas-powered locomotive, as well as kits to make diesel trains run cleaner. Mr. Burke said the ultimate goal is to have only natural-gas trains operating in the air district, which includes Los Angeles, Orange and parts of Riverside and San Bernardino counties. GM also will donate two transit buses that run on a combination of electricity and diesel fuel, and area community groups will get nine vans that run on a combination of natural gas and gasoline.

The air district is in the middle of approving rules for the kinds of vehicles fleet operators can purchase. GM wants "fuel-neutral" rules that would allow purchases of cleaner-burning diesel and diesel-hybrid vehicles if they can be proven to reduce emissions as much as natural-gas vehicles. GM and others in the diesel industry have embraced leaner-burning diesel technology as a cheaper alternative to producing heavy-duty fleet vehicles powered by natural gas and other alternative fuels.

Environmental groups want a full diesel ban, saying "green diesel" technology has failed to adequately cut the cancer-causing properties of diesel exhaust. District spokesman Bill Kelly said a testing method to determine how diesel-burning vehicles compare to natural gas should be ready in time for the governing board to vote on it next month.

(Associated Press)