On Oct. 2, 2025, EPA published an advance notice of proposed rulemaking seeking public comment on regulatory changes to the Regional Haze Rule (RHR), which requires states to submit state implementation plans (SIPs) to protect visibility in national parks and wilderness areas from manmade pollution. The agency requested input on how the RHR could be restructured to streamline states’ compliance with national visibility requirements, including developing a progress metric and clarifying SIP requirements. Comments can be submitted until Dec. 1, 2025.
Between April and June 2025, EPA proposed a “new policy” for reviewing states’ proposals to comply with federal haze standards. The new policy, if finalized, would ease compliance requirements for the regional haze program.
Background
The regional haze program, launched in 1999, requires states and the federal government to collaborate to improve visibility in 156 national parks and wilderness areas. In addition to impairing visibility, haze is also linked to serious health effects including respiratory illness, decreased lung function, and even premature death.
The program established a regulatory scheme where states submit their state implementation plans (SIPs) to the federal government for approval. The state must show how they plan to achieve “reasonable progress” toward the national visibility goal. To determine reasonable progress, the Clean Air Act requires states to evaluate four factors: “the costs of compliance, the time necessary for compliance, and the energy and non-air quality environmental impacts of compliance, and the remaining useful life of any existing source subject to such requirements.” The program also established a “uniform rate of progress” (URP) which measures the necessary progress a state must make in order to achieve compliance over the long term.
Under EPA’s new policy the state must “consider” the four statutory factors to determine reasonable progress, but the state’s analysis does not have to inform their pollution reduction plan, as long as the state can show the regulated area is below the URP.
This new policy follows Administrator Zeldin’s March 12, 2025 announcement that EPA planned to restructure the regional haze program. Comments on the Indiana, Michigan, and California proposals were due July 18, 2025 and comments on the Texas and Oklahoma proposal were due July 23, 2025.
We track implementation of EPA’s regional haze standards on our regulatory tracker.