New York environmental officials have proposed emission limits on the diesel generators and natural gas-fired engines generally used to provide back-up power at large buildings like hospitals and offices.
The Department of Environmental Conservation says the limits are on nitrogen oxide and particulates, noting the New York City area needs reductions to meet national air quality standards by a July 2018 deadline.
According to the agency, the proposal doesn't cover larger generators already regulated as major emissions sources, smaller units typically found in homes and other smaller buildings or those used only in emergencies.
The applicable units have ratings greater than 150 kilowatts in the metropolitan area and 300 kilowatts elsewhere and primarily operate on days with high electricity demand.
Environmentalists say limits are needed to close a regulatory loophole.
© 2015 AP