Sales of diesel particulate filters for commercial trucks and buses in California increased at the end of 2013 and in the first half of 2014 compared to the first half of 2013, according a survey released by the Manufacturers of Emission Controls Association.

The total number of verified DPFs sold by MECA member companies for in-use, on-road, heavy-duty diesel vehicles operating in the state during the first half of 2014 was 5,780, including both passive and active DPFs. This is a 65% increase over the 3,508 DPFs sold for this same period in 2013 but only slightly higher than compared to the 5,457 DPFs sold in the second half of 2013. These numbers follow sales of 6,261 DPFs for trucks and buses in California in 2012.

“The increase in sales in the second half of 2013 likely reflects the increase in activity by vehicles owners to meet the January 1, 2014 compliance date under the California Air Resources Board’s truck and bus regulation,” the group said in a statement.

This deadline applied to heavy-weight vehicles with 2005 to 2006 model year engines and to at least one vehicle, from any model year in fleets with three or fewer total vehicles, according to MECA.

“The continued higher sales in the first of 2014 likely reflects ARB’s recognition of good faith efforts made by vehicle owners to meet the January 1, 2014 compliance date whereby the agency allowed owners to install DPFs through July 1, 2014, without being subject to enforcement action, as long as a fleet entered into an agreement with a retrofit installer for a DPF prior to January 1, 2014,” the group said.

In a March report for the proposed amendments to the truck and bus regulation, ARB estimated that 8,195 truck owners had ordered but not installed a DPF as of January 31, 2014, according to MECA. Also, it said ARB estimated that approximately 36,000 trucks; (17,000 small fleet trucks and 19,000 large fleet trucks) would need to take steps to comply with the regulation by the end of this year. MECA expects some of these vehicle owners to comply by installing a DPF retrofit. The ARB approved the proposed amendments to the truck and bus regulation at its April 24 hearing.

In California alone, MECA claims DPFs have been used to successfully retrofit over 55,000 on-road and off-road vehicles since 2002. Overall, in the U.S., approximately 100,000 retrofit DPFs have been sold since 2001 for both on-road and off-road vehicles.

“Retrofit manufacturers are encouraged by the recent increase in DPF sales for trucks and buses in California,” said MECA’s Executive Director, Joseph Kubsh. “We also thank ARB for including diesel retrofits as a compliance option under the economic hardship extension as part of the recent amendments to the truck and bus regulation. These changes should provide lower cost pathways for small fleets, low mileage fleets, and fleets.”

MECA is a national association of companies that manufacture a variety of emission control technologies for cars, trucks, buses, and off-road vehicles and equipment, as well as stationary internal combustion engines.