The California Air Resources Board (CARB) took steps on April 22 to revise its strategy for the cleanup of on- and off-road diesel engines. 

Because of the current economy's impact, the board directed staff to return in September with specific proposals to give diesel vehicle operators more flexibility to comply with state emissions rules.

The poor economy has idled many of the diesel vehicles initially targeted by those rules. CARB's staff members have acknowledged that they previously overestimated how much pollution that construction equipment, buses and trucks emit into the air. 

"We fully recognize that the economy has had an effect on the owners and operators of big rigs, buses and construction equipment, and has also resulted in emissions from these vehicles being lower than we expected," said CARB Chair Mary D. Nichols. "We are committed to taking those impacts into consideration for our diesel clean-up program." 

The state's new off-highway diesel rules had been set to take effect this year. Some companies have already spent millions in an effort to comply with those stringent regulations. These rules call for requiring that tractors, forklifts, bulldozers and others types of diesel-powered equipment be replaced or retrofitted over the next 15 years. Large fleets have until 2020, and fleets with fewer than 20 vehicles have until 2025.

Companies with large fleets were supposed to begin replacing and retrofitting vehicles beginning March 1, the Associated Press reported. But the state is waiting for the U.S. EPA to grant a waiver from federal regulations under the federal Clean Air Act. California can't enforce its own emissions rules without the waiver.

CARB said it has asked staff to draft regulation changes to mitigate the potential effects of an unfavorable economy on affected businesses, while "keeping in mind the need to protect public health, meet federal clean-air deadlines, and continue moving forward even through uncertain times." The board also directed staff to consider approaches to give credit to firms that have already complied with the regulations, and to examine the possibility of additional loans and incentive funding for the program.

Staff presented an update on diesel emission estimates and the approach for incorporating new information on diesel fuel use, emission factors and equipment use. A new emissions estimate will be used in the rule revision process.

CARB staff will conduct a series of workshops in May and June in Los Angeles, Sacramento and Fresno to get feedback about proposed regulation revisions. The board has already extended deadlines for off-road equipment owners through AB8 2X (signed by Gov. Arnold Schwarzenegger in February 2009), including delayed compliance and credits for those who have reduced their fleet size or operating hours in response to the recession.  

In addition, CARB said it will continue its program of financial support to help owners and operators of these trucks and equipment. Over $100 million in Proposition 1B funds have been allocated for cleaning up on-road diesel trucks through retrofits or replacement. Additional funds have been made available through the Carl Moyer Grant Program, along with loans via AB 118 and federal stimulus funds.