Nine states in the northeast USA have joined together in an attempt to convince the US Environmental Protection Agency not to weaken ‘new source review’ (NSR) rules that were imposed some years ago under the Clean Air Act.

The NSR requires fossil-fuelled plants to install pollution control equipment, if they undergo major renovations or upgrading. But plant operators say the EPA has applied the rules too strictly, imposing extensive backfits even in conjunction with minor or routine maintenance.

Relaxation of the rules is supported by Midwestern states, which have large coal reserves and ageing fossil-fuelled generation. The nine northeastern states said they were effectively subsidising power from ageing plants, while still suffering from the air pollution that they caused; they have threatened legal action if the legislation is not applied strictly.