The 2011 study offers an intensive analysis of air pollution in more than 900 counties and more than 200 Metropolitan Statistical Areas (MSA) and Combined Statistical Areas (CSA), or cities and their surrounding suburbs.

FORBES: List: America's Most Polluted Cities

An analysis by the miners' union says the proposal, along with others targeting coal-related pollution, could put at risk as many as 250, 000 jobs.

WSJ: EPA Tangles With New Critic: Labor