The Environmental Protection Agency announced new rules yesterday that will cut emissions of mercury, arsenic and other toxic air emissions from coal- and oil-fired power plants, the main source of such health-damaging pollution. The rules will have an especially big impact on the South, which still depends heavily on coal power.

EPA estimates that the new Mercury and Air Toxics Standards will annually prevent as many as 11,000 premature deaths, 4,700 heart attacks, 130,000 cases of childhood asthma symptoms and 6,300 cases of acute bronchitis among children. The standards will also reduce the risk of childhood neurological damage that's been linked to mercury exposure.

"By cutting emissions that are linked to developmental disorders and respiratory illnesses like asthma, these standards represent a major victory for clean air and public health -- and especially for the health of our children," said EPA Administrator Lisa Jackson.

The rules have been in the making for more than 20 years, since Congress passed amendments to the Clean Air Act that required EPA to control toxic air pollutants including mercury. But they won't take effect immediately, as the agency is giving utilities three years to come into compliance and also encouraging permitting authorities to offer them more time if needed.

The Edison Electric Institute, the association of U.S. shareholder-owned electric companies, said it believes the Obama administration "is underestimating the complexity of implementing this rule in such a short period of time." However, Jim Rogers, CEO of North Carolina-based Duke Energy, said last month that he thinks the timeline is "tight but achievable."

Once the new standards take effect, they will reduce the public's exposure to some of the most harmful pollutants emitted by fossil-fuel plants. Along with mercury and arsenic, the standards also address toxins including lead, nickel, selenium and cyanide. Along with the Cross-State Air Pollution rule the EPA issued earlier this year, the new rules represent the most significant effort to address power-plant pollution since the initiative to curb acid rain in the 1990s.

Mercury contamination is a especially serious problem for the Southeast, whose power plants are responsible for one-fifth of the nation's mercury pollution. The region's blackwater rivers and streams, with their high levels of dissolved organic material act, as "superconverters," turning elemental mercury deposits from power plants into especially toxic methylmercury that builds up in fishes and the humans and animals that eat them.

"These standards are a huge victory for families and children as they will slash levels of mercury and other toxic air pollution that disproportionately harm kids," said John Suttles, an attorney with the Southern Environmental Law Center, which represented the American Nurses Association and Physicians for Social Responsibility in the case that led to the court order directing the EPA to end its delay in issuing the mercury rule.

Here's a list of the power plants that emitted the most mercury and mercury compounds to the air last year, according to EPA's Toxics Release Inventory. Of the top 10 mercury-emitting power plants, eight were in the South.

Top 10 U.S. power plants for air emissions of mercury and mercury compounds in 2010

1. Luminant's Big Brown Station, Fairfield, Texas (1,610 pounds)
2. Ameren's Labadie Energy Center, Labadie, Missouri (1,527 pounds)
3. Luminant's Martin Lake Station, Tatum, Texas (1,420 pounds)
4. NRG Energy's Limestone Station, Jewett, Texas (1,150 pounds)
5. American Electric Power's Pirkey Plant, Hallsville, Texas (1,070 pounds)
6. Southern Company/Alabama Power's Plant Miller, Quinton, Alabama (1,037)
7. Luminant's Monticello Station, Mount Pleasant, Texas (1,005 pounds)
8. NRG Energy's Big Cajun Plant, New Roads, Louisiana (850 pounds)
9. American Electric Power's Gavin Plant, Cheshire, Ohio (829 pounds)
10. NRG Energy's Parish Station, Thompsons, Texas (820 pounds)