Kentucky, Ohio and Pennsylvania are home to the most toxic air pollution from power plants, according to an analysis of 2010 data from the Environmental Protection Agency (EPA) conducted by the Natural Resource Defense Council (NRDC).

Kentucky ranked as the most air-polluted of the "Toxic 20" states, according to the analysis of data from the EPA's Toxic Release Inventory, a national database of self-reported pollution levels from the power industry, which includes mercury, hydrochloric acid and other pollutants. Ohio, Pennsylvania, Indiana and West Virginia followed to make up the five most-polluted states.

However, the analysis also concluded that air pollution from power plants decliend by 19 percent in 2010 from 2009. The NRDC credited that improvement to two factors: an increase in natural gas use, which the group noted is both cheaper and cleaner than coal, and increased pollution controls being put in place in anticipation of EPA's new Mercury and Air Toxic standards that start in 2015.

The NRDC is a self-described grassroots environmental action group that advocates for greater pollution controls. In releasing the report, the group warned against efforts to reverse the EPA's new standards. The report pointed to estimates that the standards would reduce mercury air pollution by 79 percent starting in 2015, prevent as many as 11,000 premature deaths, and save up to $90 billion in health-care costs.

"We have a long way to go," John Walke, the group's clean air director, said in a conference call. "The case for cleaning up these states is clear."

Eighteen of the 20 "Toxic 20" states were repeats from 2009. Delaware and Mississippi moved into the rankings in 2010, and the latter saw the most substantial increase in electric air pollution of any state: 97 percent. Other states, however, made significant improvements. Maryland dropped from fifth in 2009 to 19th in 2010, reducing pollution by 88 percent. Florida cut its pollution by 50 percent and fell from third to sixth.

The NRDC's "Toxic 20" were:

  • Kentucky
  • Ohio
  • Pennsylvania
  • Indiana
  • West Virginia
  • Florida
  • Michigan
  • North Carolina
  • Georgia
  • Texas
  • Tennessee
  • Virginia
  • South Carolina
  • Alabama
  • Missouri
  • Illinois
  • Mississippi
  • Wisconsin
  • Maryland
  • Delaware
  • Governing has marked coal power plants that could be affected by the new EPA standards in the map below. Notably, many reside in the NRDC's "Toxic 20."

    The Associated Press reports more than 32 mostly coal-fired power plants will close and another 36 plants could also be forced to shut down as a result of new EPA rules regulating air pollution.

    Click the icons in the map to view details for each plant affected by the EPA rules. Red icons indicate at least one unit will retire; yellow icons denote at least one unit at a power plant is at risk of retirement.