On Dec. 11, 2008, the Board approved for adoption the Truck and Bus regulation to control emissions from nearly all existing diesel powered heavy-duty trucks and buses operating in
California. The regulation became effective under California law on Jan. 8, 2010.

The regulation applies to diesel fueled trucks and buses with a gross vehicle weight rating (GVWR) greater than 14,000 pounds that are privately owned, federally owned, and to publicly and privately owned school buses.

Local and state government owned diesel fueled trucks and buses are already subject to other ARB regulations. Reducing emissions from in-use trucks and buses is necessary to meet federally imposed clean air standards and to reduce the adverse health effects from
truck and bus pollution.

On December 17, 2010, the staff recommended amendments, which are presently pending adoption, that would delay the initial requirement to install particulate matter (PM) retrofit filters by one year to Jan. 1, 2012, and extend the time before a vehicle equipped with a PM filter would have to have an engine that meets 2010 model year emission standards.

The amendments also defer engine replacements for vehicles without PM filters for two years until Jan. 1, 2015. Prior to 2020, replacements are limited to 20 year old or older trucks that are not equipped with PM filters.

By Jan. 1, 2023, most vehicles will need to be equipped with an engine meeting 2010 model year emission standards.