WASHINGTON The 2010 engines of Volvo, which supplies engines to Prevost Car, have been certified by federal and California environmental regulators.

Volvo becomes the first diesel engine manufacturer to gain official approval for its 2010 reduced-emissions engines.

Volvo said the U.S. Environmental Protection Agency and the California Air Resources Board certified its 11- and 13-liter engines.

All heavy-duty Volvo engines use selective catalytic reduction technology to meet the 2010 emissions standards.

Rival engine manufacturers Cummins Inc. and Detroit Diesel Corp. also have filed 2010 certification applications with EPA and CARB for their SCR engines, but have not yet received approval.

"EPAs certification of these engines is a crucial milestone in Volvos journey to producing the cleanest diesel engines in the world," said Scott Kress, Volvos senior vice president for sales and marketing.

The USEPA has been tightening U.S. emissions standards on nitrogen oxide compounds and particulate matter from diesel engines for much of this decade, having done so most recently in January 2007.

On Jan. 1, the federal standard for NOx, a major component of smog, drops to 0.2 gram per brake horsepower-hour from 1.2 grams per unit of output. The 2010 federal standard for particulate matter, or soot, will remain at 0.01 g/bhp-hr, where it was set in 2007.

While Volvo received approval for its heavy-duty engines, Cummins, the only independent engine maker, is seeking approval for heavy-duty and midrange products.

"Cummins has submitted all required paperwork and supporting documentation for the EPA certification of our 2010 on-highway engines. We have been working closely with the EPA throughout the year in preparation for the certification process and therefore dont anticipate any issues with EPA and CARB certification for our 2010 products," said Christy Nycz, spokeswoman for the engine business of Cummins.

Detroit Diesel Corp., a division of Daimler Trucks North America, filed papers with EPA in late September for its DD13 and DD15 models.

Cummins and DDC are both using SCR for 2010.

Among other engine makers, Caterpillar is leaving the North American bus and truck engine market as of Dec. 31 and will not offer 2010 on-highway products.

Navistar, the maker of IC brand buses, International brand trucks and MaxxForce engines, will be seeking certification for three heavy-duty and four medium-duty engines. It is the only OEM using exhaust gas recirculation, or EGR, shunning SCR.