Cross-posted from the Wonk Room.

Today, the Obama administration proposed a sweeping plan to reduce power plant emissions that cross state lines and kill tens of thousands of Americans every year. The proposed Clean Air Transport Rule replaces the Bush administration's so-called Clean Air Interstate Rule that was shot down by the courts because it permitted so much interstate emission trading that even some power companies filed suit. A federal court ordered EPA to fix the shaky legal grounds of the Bush plan. Power industry pollution remains so pervasive -- and so often blows from one state to another -- that it basically handcuffs state efforts to reduce pollution within a state's borders. As EPA noted in a fact sheet:

Specifically, this proposal would require significant reductions in sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions that cross state lines. These pollutants react in the atmosphere to form fine particles and ground-level ozone and are transported long distances, making it difficult for other states to achieve national clean air standards.

Emissions reductions will begin in 2012. By 2014, "the rule and other state and EPA actions would reduce power plant SO2 emissions by 71 percent over 2005 levels," and power plant NOx emissions "would drop by 52 percent."

It has been nearly 40 years since passage of the landmark Clean Air Act of 1970. Since then, we've made significant progress towards cleaner air. Cars are dramatically cleaner. Lead is gone from gasoline. New trucks no longer belch out the familiar puff of smoke. And EPA statistics document the continuing overall trend of cleaner air with respect to traditional pollutants. Despite that progress, one major source of air pollution remains a notorious problem: the electric power industry. Indeed a recent assessment by Ceres, the Natural Resources Defense Council, and several power companies described the footprint of fossil-fueled power plants:

In 2008, power plants were responsible for 66 percent of SO2 [sulfur dioxide] emissions, 19 percent of NOx [smog-forming nitrogen oxides] emissions, and 72 percent of toxic mercury emissions in the U.S. -- not to mention that the electric industry also pumps out nearly 40 percent of the nation's heat-trapping carbon dioxide emissions.

A recent Clean Air Watch survey noted that no fewer than 40 states and the District of Columbia have experienced unhealthful levels of smog so far this year.

The Obama EPA hopes to put the cleanup concept on a sound legal footing by limiting the amount of emission trading. Anyone interested in clean air should hope this plan holds up in court. EPA projects the plan could prevent up to 36,000 premature deaths a year -- and bring monetary benefits of at least $120 billion a year -- at an annual cost of about $2.2 billion.

It is a big step towards taming the environmental monster known as the coal-fired power plant. But it is only the first step. EPA plans nest year to propose rules to limit mercury and other toxic emissions including arsenic, dioxins, and hydrochloric acid. The power industry has been evading toxic pollution requirements for two decades.

EPA has also pledged to follow up with a subsequent interstate pollution rule, if needed, as it surely will be, to make further reductions in smog-forming power plant emissions after the agency moves to set tougher national health standards for ozone, or smog, as it plans to do by the end of the summer.