SACRAMENTO – In an action today by the California Air Resources Board (ARB) the state's transit agencies were given more flexibility to reduce air pollution from buses, and bus manufacturers were provided a mechanism to certify new hybrid-electric buses (HEBs.)

"These changes offer more ways for transit agencies to comply with our regulations while keeping us on the path to cleaner buses," said Dr. Alan Lloyd, ARB Chairman. "We expect to see increasing usage of hybrid-electric buses in the coming years," Dr. Lloyd said.

The ARB's transit bus fleet rule was originally passed in February 2000. Today's changes allow transit agencies to count the greater emission reductions that come from using HEBs. Additionally, transit agencies are offered a wider range of options for cutting particulate matter (PM) emissions from buses.

The original regulation relied only on filters and traps to reduce PM emissions, and was stymied by the unavailability of PM filters for the oldest, most polluting buses. The amended regulations allow transit agencies to use a variety of mechanisms to reduce their soot emissions gradually over time.

By 2007, transit agencies that have chosen to use diesel rather than alternative fuels, must reduce PM emissions 85 percent below their 2001 emission levels. Transit agencies choosing to purchase new alternative fuel buses have until 2009 to reduce PM emissions from any diesel buses remaining in their fleets.

The transit bus rule is expected to reduce 33 tons per year of PM emissions state-wide by 2010.