The Continental Carbon plant sits on the southern outskirts of Ponca City, Okla. Until August, the plant was on an internal EPA "watch list," for violating rules of the Clean Air Act. David Gilkey/NPR hide caption
Poisoned Places: Toxic Air, Neglected Communities Toxic air pollution, involving nearly 200 chemicals deemed so harmful to health Congress sought to bring emissions under control 21 years ago, persists in hundreds of U.S. communities.
Special Series
Poisoned Places: Toxic Air, Neglected Communities
Toxic air pollution persists in hundreds of U.S. communities.
The Continental Carbon plant sits on the southern outskirts of Ponca City, Okla. Residents blamed the plant, which produces a black dust known as carbon black, for polluting their city. David Gilkey/NPR hide caption
The Ash Grove Cement Kiln, as seen from an aerial photograph, sits on the northern edge of Chanute, Kan. David Gilkey/NPR hide caption
Jeff Galemore leans on his pickup truck near the Ash Grove Cement plant in Chanute, Kan. He and his family are concerned about the toxic emissions and are fighting for independent testing downwind. David Gilkey/NPR hide caption
A haze can be seen at night hovering over the Asarco copper smelter, which turns copper ore into nearly pure copper bars. Emma Schwartz/Center for Public Integrity hide caption
An evening view of the Exxon Mobil oil refinery complex in Baton Rouge, La. John W. Poole/NPR hide caption
The Houston Ship Channel is home to a wide range of heavy industry, including chemical processing plants and petrochemical refineries. Richard Harris/NPR hide caption
The Grain Processing Corp. plant in Muscatine, Iowa. Chris Hamby/Center for Public Integrity hide caption