U.S. environmental regulators finalized a rule on Thursday to slash air pollution from coal-fired power plants in 27 states east of the Rocky Mountains that result in unhealthy levels of smog and soot.

The Environmental Protection Agency measure, known as the Cross State Air Pollution Rule, will add costs for some power generators, but should cut health care bills for Americans.

Companies that could see higher costs include large coal burners Southern Co, Duke Energy and American Electric Power.

“No community should have to bear the burden of another community’s polluters, or be powerless to prevent air pollution that leads to asthma, heart attacks and other harmful illnesses,” said EPA Administrator Lisa Jackson.

The EPA rule will reduce power plant sulfur dioxide emissions by 73 percent by 2014, from 2005 levels, when combined with state environmental laws. It will cut nitrogen oxide emissions by 54 percent by 2014. Those cuts are slightly deeper than ones proposed by the EPA last year.