The little-known reason places with names like Badlands, Wind Cave, and Great Basin could soon see sullied air is a federal proposal that would lower the bar for developers seeking permits to build upwind of the parks, these critics say.

Despite blunt internal criticism by its own staff experts, the Environmental Protection Agency (EPA) is proceeding with a plan by year's end to revise regulations under the Clean Air Act that currently safeguard areas with some of the nation's cleanest air.

"We're talking about more pollution in national parks and wilderness, not less, because of this proposed change," says a federal air-quality expert, who asked not to be named because he was not permitted to speak to the press.