As the U.S. Environmental Protection Agency nears its Dec. 16 date with coal-fired power plants -- that's when the agency plans to finalize its mercury and air toxics rule -- the lobbyists must surely be working overtime.

Environmental and public health groups say the rule, which would require significant reductions of emissions, is long overdue and should be implemented ASAP. Industry says that the rule is onerous and that it needs more time.

Mercury, which is emitted when coal is burned, is a neurotoxin that hampers the development of young children and fetuses. Scrubbers to limit mercury would also limit other air toxins that can cause asthma attacks, heart attacks, strokes and premature death.

When the EPA first proposed its new rule, the agency estimated it would avoid between 6,800 and 17,000 premature deaths each year, and would result in annual savings of $48 to $140 billion in health care costs, lost productivity due to sick days, etc.

The American Lung Association has relesed television ads in Pennsylvania urging the EPA to protect public health.

"The advertisement serves as an important reminder of those who suffer most from dirty air and poor air quality created by power plant emissions," said Deborah Brown, President and CEO of the American Lung Association in Pennsylvania, in a press release. "Children rely on adults to protect them and it is our responsibility to ensure they have healthy air to breathe. This is especially important for over 250,000 children and teens with asthma in Pennsylvania."

The focus on Pennsylvania is apt -- it has more than 30 coal-fired power plants.  Some have already cleaned their emissions, but overall, they contribute much to air pollution.

Yesterday, a national nonprofit, the Environmental Integrity Project, released its analysis of mercury and toxic emissions from the nation's power plants. Using data from 2010, it ranked the dirtiest dozen in the U.S., "in terms of sheer pounds of emissions of four highly toxic heavy metals – arsenic, chromium, lead, and mercury."  They included three in Pennsylvania -- Genon's Shawville Station (No. 3), Edison International's Homer City Plant (No. 7) and FirstEnergy's Bruce Mansfield Power Plant (No. 9).

Ilan Levin, associate director of the EIP, said in a press release: "The only thing more shocking than the large amounts of toxic chemicals released into the air each year by coal- and oil-fired power plants, is the fact that these emissions have been allowed for so many years. For decades, the electric power industry has delayed cleanup and lobbied against public health rules designed to reduce pollution. But, the technology and pollution control equipment necessary to clean up toxic emissions are widely available and are working at some power plants across the country. There is no reason for Americans to continue to live with unnecessary risks to their health and to the environment."