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How the latest Supreme Court air pollution case could bring more smog to Pennsylvania

Islands and other nature along rivers.
Janet Butler
The Good Neighbor rule is meant to reduce ozone-forming pollution from industrial facilities and power plants, like this one along the Ohio River, from states like Ohio that wafts downwind to states like Pennsylvania. 

The U.S. Supreme Court heard arguments Wednesday on whether a clean air rule should be put on hold while a case against it is considered by a lower court.

Ohio, West Virginia and Indiana are trying to stop the U.S. Environmental Protection Agency from enforcing what’s called the “Good Neighbor” rule of the Clean Air Act, which is meant to reduce ground-level ozone pollution (or smog) that drifts across state lines.

According to an EPA Fact Sheet, when the agency issued its final “Good Neighbor Plan” in March 2023, it initially required 23 states, which had failed to comply with revised ozone standards, to reduce emissions of nitrogen oxides (NOx) that contribute to smog.

EPA said that the Good Neighbor Plan would “prevent up to 1,300 premature deaths, reduce hospital and emergency room visits for thousands of people with asthma and other respiratory problems” in 2026, according to the fact sheet.

Because of litigation that followed, the Good Neighbor rule currently requires only 11 “upwind” states to reduce ozone-forming emissions from power plants and industrial facilities affecting the air quality in “downwind” states.

“Pennsylvania is downwind from a lot of heavy pollution from certain upwind states, such as Ohio, West Virginia and Indiana,” said Alex Bomstein, legal director for the Philadelphia-based Clean Air Council. “Because of that, we receive a lot of the pollution that’s produced in those states.”

Along with other environmental groups, the Clean Air Council filed court documents supporting EPA’s rule. They argue that upwind states create smog-producing nitrous oxide, which causes premature deaths and increased hospital visits for downwind state residents.

Pennsylvania is among the upwind states supporting EPA’s rule in court. According to Bomstein, Aliquippa, Beaver and other western Pennsylvania towns are especially at risk from this pollution.

“This is why they call it the Good Neighbor rule. When you have a state right next store, you want them to act responsibly so you don’t bear the brunt of their pollution,” he said.

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Ohio v. EPA

The U.S. Court of Appeals for the District of Columbia Circuit is considering the argument by Ohio, West Virginia and Indiana, along with utilities, gas producers and manufacturers like U.S. Steel, that the Good Neighbor rule was a federal overreach, and it will be costly and ineffective for them to comply.

Ohio is seeking a stay, or pause, so the rule is not enforceable during the litigation. The D.C. Circuit denied that request and said the EPA rule could go into effect.

But Ohio appealed to the US Supreme Court, which heard arguments on the stay in Ohio v. EPA on Wednesday.

“The Supreme Court, in some sense, is being asked to butt in now, early in the process. Historically that hasn’t happened,” explained University of Pennsylvania law professor Cary Coglianese, who specializes in regulatory and environmental law.

While the high court is only deciding on the stay, he says the court decision here could have large implications for EPA’s authority to regulate this air pollution.

“If they win on the stay, it sends a strong signal that the U.S . Supreme Court is very skeptical of the EPA’s federal plan.”

A decision on the stay is expected by June.

Read more from our partners, The Allegheny Front.

Julie Grant is senior reporter with The Allegheny Front, covering food and agriculture, pollution, and energy development in Pennsylvania and Ohio. Throughout her career, she has traveled as far as Egypt and India for stories, trawled for mussels in the Allegheny River, and got sick in a small aircraft while viewing a gas well pad explosion in rural Ohio. Julie graduated from Miami University of Ohio and studied land ethics at Kent State University. She can be reached at