Air Plan Approval; Missouri; Clean Data Determination for the 2015 8-Hour Ozone Standard for the St. Louis Nonattainment Area

The EPA is accepting comment on a determination that the Missouri portion of the St. Louis, MO-IL bi-state nonattainment area has attained the 2015 ozone National Ambient Air Quality Standards (NAAQS) under EPA’s Clean Data Policy, also known as a clean data determination. This action, if finalized will suspend certain nonattainment planning requirements as long as the area continues to attain the standard. This action also accepts comment on EPA’s concurrence on Missouri’s November 3, 2025, exceptional events demonstration.