DIAMOND BAR, Calif. -- The South Coast Air Quality Management District, the air pollution control agency for much of Southern California, has proposed a rule requiring government agencies and their contractors, including school bus operators, to make a gradual shift to "clean burning" fuels.

All fleets of 15 or more vehicles operated by public agencies or private businesses to transport passengers and cargo under contract to a government agency would be required, beginning in 2002.

Clean-burning fuel includes compressed natural gas (CNG), liquefied petroleum gas (LPG), liquefied natural gas, methanol, electric batteries and gasoline. AQMD's Proposed Rule 1190 - Clean On-Road Vehicles for Government and Airport Operations will be brought before the district governing board in February and a public workshop on the matter is scheduled to take place Feb. 19.