Of this total, approximately 39% were diesel oxidation catalysts and 32% were diesel particulate filters (includes both passively and actively regenerated filters). This total also includes 6,914 retrofit closed-crankcase filters. In California, 5,606 diesel retrofit devices were sold, of which 96% were diesel particulate filters. Worldwide, compared to the results of MECA’s 2007 survey, the overall 2008 sales figures remained about the same (43,118 diesel retrofit devices were sold by MECA member companies worldwide in 2008 vs. 44,625 in 2007).

MECA expects sales of diesel retrofit devices to increase over the coming years as more funding becomes available at both the federal and local level to reduce emissions from in-use diesel vehicles. In particular, the US Environmental Protection Agency (EPA) received $300 million in DERA (Diesel Emissions Reduction Act) economic stimulus funding from Congress in March 2009 to fund clean diesel projects through the agency's National Clean Diesel Campaign (NCDC). Last month, EPA announced its Request for Proposals (RFP) for $120 million in FY 2009/2010 DERA funding for clean diesel projects under the NCDC.