On February 27, 2026, U.S. EPA issued a proposed rule that, if finalized, would position the Cleveland, Ohio Nonattainment Area for redesignation to attainment of the 2015 ozone National Ambient Air Quality Standard (NAAQS). U.S. EPA proposes taking two critical steps toward redesignation in the proposed rule: (1) determining that the Cleveland Nonattainment Area has attained the 2015 Ozone NAAQS based on certified ambient air monitoring data for the 2023-2025 design period, which relied on an exceptional events request submitted by Ohio EPA, and (2) taking final action on U.S. EPA’s concurrence with Ohio EPA’s exceptional events request. Notably, U.S. EPA determined that Ohio EPA’s demonstration met the exceptional events criteria by demonstrating a clear, causal relationship between wildfire events in 2023 and high ozone values recorded at various monitors in the Cleveland area on June 1, 2 and 29, 2023.
U.S. EPA’s determination in response to Ohio EPA’s exceptional events request is significant as it allows EPA to rely on the calculated values that exclude the wildfire event-influenced data for purposes of demonstrating the Cleveland area’s attainment of the 2015 Ozone NAAQS. In connection with U.S. EPA’s attainment determination, the Agency also proposed to suspend – as long at the Cleveland area continues to attain the 2015 Ozone NAAQS – the requirements that Ohio EPA would have to implement to bring the area into attainment – i.e. submittal of an attainment demonstration and Reasonable Available Control Measures (RACM), Reasonable Further Progress plans, and other State Implementation Plan requirements related to attainment of the NAAQS.
It is important to note that U.S. EPA’s proposed rule does not constitute a redesignation of the Cleveland area to attainment of the 2015 Ozone NAAQS. However, to that end, Ohio EPA submitted a request to redesignate the area to attainment on December 8, 2025. U.S. EPA indicated in the proposed rule that it will take action on the redesignation request in a separate rulemaking. Stay tuned.