On December 12, 2008, California passed diesel emission regulations that are the toughest in the United States.
The rule, which was passed by the California Air Resources Board (ARB), requires replacement of exhaust filters and new engines staggered between 2011 and 2022. The ARB stated on its website that the new regulation is: “directly aimed at cleaning up harmful emissions from the estimated one million heavy-duty diesel trucks that operate in California.” The diesel regulation applies to about 400,000 trucks that are registered in the state, and about 500,000 out-of-state trucks that do business in California.
Some truck companies have complained about the cost of this regulation. The owner of one small truck company estimated it would cost $7 million to replace most of his 35 trucks by 2014, AP reported.