The Environmental Protection Agency has proposed a regulation that aims to cut sulfur dioxide and nitrogen oxides emissions that are carried downwind from powerplants in 31 eastern states and the District of Columbia, posing harm in other parts of the country.

EPA says that the proposed rule, which EPA Administrator Lisa Jackson signed on July 6, would cut SO2 emissions by 2014 by 71% from 2005 levels and trim NOx emissions by 52%. McCarthy says the first phase of the reductions would take place in 2012, assuming that the rule becomes final in 2011.

Gina McCarthy, EPA's assistant administrator for air and radiation, told reporters that the proposal is "a large and important step in EPA's effort to protect public health as well as help the states reduce air pollution and attain Clean Air Act standards."

The regulation deals with interstate "transport" of emissions that are carried "long distances, making it difficult for states downwind to achieve national clean air standards," McCarthy says.

It is a response to a 2008 federal appeals court decision that required the agency to rewrite the 2005 Clean Air Interstate Rule (CAIR). McCarthy says, "Although this rule gets larger emission reductions more quickly than CAIR required, additional emission reductions will be necessary to help states' attainment and future air quality standards."

She adds, "It doesn't claim to have long-term answers, but it does claim to try to address the issues in a very robust and straightforward and environmentally sound way."

She also says that EPA has begun work on applying the newly proposed SO2 and NOx "template" to another transport rule it plans to propose in 2011 to address an ozone standard it will issue later this year.

EPA estimates that the rule would avoid 14,000 to 36,000 deaths and produce $120 billion to $290 billion in annual benefits in 2014, compared with costs of $2.8 billion per year.

The agency will take public comments on its proposal for 60 days after it is published in the Federal Register.

Bruce Nilles, the Sierra Club's deputy conservation director, calls the EPA proposal a "step forward for people who want clean air." He adds, "While a thorough review and comment period remains to be completed, the Sierra Club is pleased to see this progress made."