Air pollution is a complex problem. For one, it does not adhere to state boundaries; a smokestack in one state can contribute to pollution problems in another, even a downwind state hundreds of miles away. What’s more, air pollution’s impacts are not confined to just the air. What goes up must come down, and air pollutants are eventually deposited on the ground where they are washed into rivers, lakes, and streams.
The Environmental Protection Agency (EPA) has tried for decades to address the thorny problem of interstate air pollution. Last week, the U.S. Supreme Court revived the EPA’s Cross-State Air Pollution Rule, the agency’s most recent and comprehensive attempt to tackle the issue. The decision in EPA v. EME Homer City Generation, L.P. will mean that large sources of nitrogen oxide and sulfur dioxide emissions in certain states will be subject to more stringent air pollution requirements moving forward.
Reversing the U.S. Court of Appeals for the District of Columbia Circuit, the Court deferred to the EPA’s interpretation of the portion of the Clean Air Act that requires emission controls in states to ensure that no source “contribute[s] significantly” to violations of air quality standards in another state (known as the “good neighbor” provision). The EPA interpreted that directive to require emissions reductions by states based on the availability of cost-effective control methods, a reading of the law that the Court found not only reasonable but also “efficient and equitable.”
The decision has national implications, but holds particular promise for ongoing efforts to restore the Chesapeake Bay. Because more than one-third of the nitrogen pollution in the Bay comes from air pollution, stronger federal air pollution rules should mean that Bay states see reductions in pollution coming from upwind and in-state sources.
CPR Member Scholar Victor Flatt and I summarize the decision here. The Case Brief provides a history of EPA’s attempt to define the scope of the Clean Air Act’s good neighbor provision, a summary of the majority’s reasoning, and an analysis of how the decision might affect efforts to clean up the Chesapeake Bay.
By endorsing the EPA’s overall approach to reducing interstate air pollution, the Supreme Court allowed the regulation to move forward with the promise of cleaner air, and a cleaner Chesapeake.