Outdated conventional power plants in the United States emit three times as much air pollution as those built to current standards, according to "Lethal Loophole," a report issued in June by the US Public Interest Research Group (USPirG), a leading consumer group. In fact, the report claims, older mostly coal-burning power plants are the country's single largest source of the pollution that causes global warming and smog. "Lethal Loophole" also lists 559 fossil fuel plants, mostly in the Midwest or south, that received exemptions when the Clean Air Act was passed and emit at least 20 extra tons of pollution yearly. The report is the first to analyse data collected by the US Environmental Protection Agency (EPA) in 1997. "This lethal loophole more than triples electric industry air pollution," says USPirG's staff attorney, Rebecca Stanfield. The release of the report coincides with the beginning of a period of public commentary on a new EPA rule limiting air pollution in the 22 eastern states.