The U.S. Environmental Protection Agency issued final regulations capping pollution from coal-fired power plants.

The Cross-State Air Pollution Rule, aimed at cutting emissions that contribute to pollution problems in other states, requires coal companies in 27 states to slash emissions of sulfur dioxide and nitrogen dioxide by 73 percent and 54 percent, respectively, from 2005 levels by 2014.

EPA says the new rule will slash hundreds of thousands of tons of smokestack emissions that travel through the air leading to soot and smog, thus "threatening the health of hundreds of millions of Americans living downwind."

The new rule replaces a set of 2005 Bush administration regulations that courts had ordered EPA to revise.

"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," EPA Administrator Lisa P. Jackson said Thursday in announcing the new regulations.

"These Clean Air Act safeguards will help protect the health of millions of Americans and save lives by preventing smog and soot pollution from traveling hundreds of miles and contaminating the air they breathe."

EPA said the new regulations will prevent 34,000 premature deaths, 15,000 heart attacks and 400,000 cases of asthma starting in 2014, amounting to $280 billion a year in benefits.

Still, the NOx emissions cap "is simply not sufficient to control the magnitude of emissions" that come from power plants, said National Association of Clean Air Agencies Executive Director Bill Becker, Washington's The Hill newspaper reports.

EPA said projected compliance costs are $800 million a year.

The new regulations could also force the retirement of a number of coal plants, thus raising electricity costs, said Pat Hemlepp, a spokesman for American Electric Power, which has plants in 11 states from Texas to Michigan.

"Our most significant concern remains the unrealistic compliance timetables of this and a series of other EPA rules that target coal-fueled generation,'' Hemlepp told The Washington Post.

The new regulations are among the most expensive ever imposed by the agency on coal-fueled power plants, says the American Coalition for Clean Coal Electricity.

"The EPA is ignoring the cumulative economic damage new regulations will cause," said the group's president, Steve Miller, in a statement. "America's coal-fueled electric industry has been doing its part for the environment and the economy, but our industry needs adequate time to install clean coal technologies to comply with new regulations. Unfortunately, EPA doesn't seem to care."

Coal provides nearly half of America's electricity supply, the group says.