The Trump administration on Wednesday proposed eliminating federal oversight of interstate air pollution by approving eight states to regulate ozone emissions as they determine appropriate, the Environmental Protection Agency said.
EPA Administrator Lee Zeldin described the action as “cooperative federalism,” replacing what he called a “heavy-handed, one-size-fits-all, federal mandate.” The affected states are Alabama, Arizona, Kentucky, Minnesota, Mississippi, Nevada, New Mexico and Tennessee, which the EPA under the Biden administration had found had not sufficiently controlled emissions traveling across state lines.
Environmental groups said the proposal would harm downwind states by allowing industrial pollution to travel without federal constraint. “Letting states off the hook while their pollution continues harming air quality in neighboring states is dangerous,” said Zachary Fabish, a Sierra Club lawyer.
The proposal marks another step in the Trump administration’s effort to roll back environmental regulations and represents a significant shift in how federal authorities approach interstate air pollution, moving responsibility from EPA enforcement to individual state decisions.
Background on the Good Neighbor Rule
The “good neighbor” rule has been EPA policy for decades as part of the Clean Air Act framework, designed to prevent one state’s pollution from degrading air quality in another state. The rule required that states demonstrate they would not add significantly to air pollution problems in neighboring areas.
Under Presidents Obama and Trump and through the Biden administration, the EPA enforced the rule through a process of approving or rejecting state air-quality control plans. States that the EPA determined would contribute significantly to interstate pollution were required to revise their plans.
The Supreme Court Decision
In 2024, the Supreme Court ruled that the EPA lacked clear statutory authority to enforce the good neighbor rule in the manner it had traditionally applied it. The decision did not eliminate the underlying obligation for states to avoid significantly contributing to air pollution in other states, but it removed the EPA’s established enforcement mechanism.
The Trump Administration’s Response
Now, three years into the second Trump presidency, the EPA is rewriting how the rule functions. Instead of the federal agency enforcing a unified standard, each state would submit its own plan for managing ozone-forming emissions. If the EPA approves a state’s plan—finding that it has adequate data and does not significantly harm neighbors—that state would no longer face federal oversight on the issue.
“These states will be able to advance cleaner air now for their communities, instead of waiting for overly burdensome federal requirements years from now,” Zeldin said in a statement.
The EPA statement indicated that the agency finds the eight state plans to have “adequate data demonstrating these states are not interfering with ozone attainment” required by federal air-quality standards.
Environmental Opposition
Environmental groups including the Sierra Club argue that the proposal eliminates a critical mechanism for addressing air pollution that crosses state boundaries. Individual states cannot unilaterally solve regional air-quality problems when neighboring states emit pollutants that drift across borders and degrade conditions downwind.
“Once again, Donald Trump and Lee Zeldin are choosing to protect aging, dirty and expensive coal plants and other industrial polluters over strong federal clean air protections that address interstate pollution problems,” Fabish said.
The Sierra Club lawyer also disputed the characterization that the eight states’ plans would adequately protect air quality. “Letting states off the hook while their pollution continues harming air quality in neighboring states is dangerous,” Fabish said, adding that the move will make “Americans sicker and pay more for energy while doing so.”
Environmental groups noted that air pollution from heavily industrialized Midwestern states such as Indiana and Ohio frequently reaches East Coast states such as Connecticut and Delaware. Air does not recognize state boundaries, they argue, making federal coordination essential to protect downwind communities.
Public Comment and Future Steps
The EPA’s proposal is not final. The agency will accept public comment for at least 30 days after the rule is published in the Federal Register. Environmental groups, affected states, and other stakeholders will have an opportunity to submit remarks before the EPA makes a final decision.
The EPA also indicated that in the near future, it intends to take separate action addressing “interstate transport” obligations for states not included in Wednesday’s proposal, signaling that the administration’s overhaul of the good neighbor rule extends beyond the eight states named Wednesday.