Low urgency

Air Plan Approval; Illinois; Clean Data Determination for the Illinois Portion of the St. Louis Area for the 2015 Ozone Standard

Detected August 13, 2026 · in Environmental & Emissions Compliance (EPA)

EPA has determined that the Illinois portion of the St. Louis area now meets the 2015 ozone standard, meaning certain Clean Air Act requirements for that area are suspended.

Aforeworn detected this change in the Environmental & Emissions Compliance (EPA) space on August 13, 2026 and published this briefing so affected operators are forewarned rather than caught off guard. It is rated Low urgency. Manufacturers, power generators, chemical processors, and other sources in the Illinois portion of the St. Louis area subject to ozone-related requirements. should confirm how it applies to their specific situation before acting. There is a time constraint attached: Not specified in the excerpt.. Acting after that point can mean penalties, a lapsed licence, or lost eligibility — exactly the kind of surprise Aforeworn exists to prevent. Aforeworn monitors Environmental & Emissions Compliance (EPA) continuously and turns every detected change into a plain-English briefing like this one, so you always know first. Forewarned is forearmed.

What changed

EPA's clean data determination means that, for the Illinois portion of the St. Louis area, the obligation to submit certain ozone-related SIP revisions and to implement associated control measures is suspended for as long as the area continues to meet the standard.

Who it affects

Manufacturers, power generators, chemical processors, and other sources in the Illinois portion of the St. Louis area subject to ozone-related requirements.

What you must do

No immediate action required; monitor EPA's final rule for any specific compliance obligations or future changes.

Deadline

Not specified in the excerpt.

Source: https://www.federalregister.gov/documents/2026/08/13/2026-16514/air-plan-approval-illinois-clean-data-determination-for-the-illinois-portion-of-the-st-louis-area

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