"The system Congress set up 21 years ago to clean up toxic air pollution still leaves many communities exposed to risky concentrations of benzene, formaldehyde, mercury and many other hazardous chemicals.
Pollution violations at more than 1,600 plants across the country were serious enough that the government believes they require urgent action, according to an analysis of EPA data by NPR and the Center for Public Integrity. Yet nearly 300 of those facilities have been considered "high priority violators" of the Clean Air Act by the Environmental Protection Agency for at least a decade.
About a quarter of those 1,600 violators are on an internal EPA 'watch list,' which the agency has kept secret until now.
EPA estimates facilities across the country emit 40 percent less toxic emissions in 2005 than they did in 1990, but toxic air pollution has persisted in communities like Ponca City, Okla., Hayden, Ariz., Tonawanda, N.Y., and Muscatine, Iowa."
Elizabeth Shogren reports for NPR's Morning Edition November 7, 2011, in part one of a four-part series reported in collaboration with the Center for Public Integity's iWatch News.