EPA has issued national emission standards for hazardous air pollutants (NESHAPs) for reciprocating internal combustion engines. 75 Fed. Reg. 9,647 (03/03/10). The standards apply to engines, used to generate electricity and power equipment at factories and other facilities, that “either are located at area sources of hazardous air pollutant emissions or that have a site rating of less than or equal to 500 brake horsepower and are located at major sources of hazardous air pollutant emissions.” The rule requires facility operators to reduce emissions of carbon monoxide, used as a surrogate for air toxics, by as much as 70 percent and to take steps to limit emissions of metallic toxics by 2013. The rule is effective immediately.