Minneapolis-based Donaldson Co. has announced that the Environmental Protection Agency (EPA) has approved its Diesel Oxidation Catalyst ("DOC") muffler and Spiracle crankcase ventilation filter as an emissions-control retrofit system for diesel-powered buses and medium- and heavy-duty trucks.

Donaldson said its DOC muffler and crankcase filter combination can reduce diesel engine emissions from 25% to 50% and that approval under the EPA's Environmental Technology Verification Program will enable the company to offer its system for vehicles manufactured since 1991.