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

**Action Urgency Score:** 30/100

| Field | Value |
|---|---|
| Agency | Environmental Protection Agency |
| Type | Final rule |
| Action | Final rule. |
| Published | 2026-08-13 |
| Effective | 2026-09-14 |
| Significant | No |
| CFR parts | 40 CFR 52 |
| Summary | The Environmental Protection Agency (EPA) is determining under the Clean Air Act (CAA) that the Missouri portion of the St. Louis, MO- IL bi-state nonattainment area has achieved clean data for the 2015 8- hour ozone National Ambient Air Quality Standard (NAAQS or standard). This determination of clean data is based upon complete, quality- assured, and certified ambient air monitoring data for the 2023-2025 design value period showing that the Missouri portion of the area achieved attainment of the 2015 ozone NAAQS. The 2023-2025 design value relies upon EPA concurrence on a portion of the exc |
| Document number | 2026-16515 |

## Why this score
- Final rule.

Source: Federal Register API (Office of the Federal Register) (https://www.federalregister.gov/documents/2026/08/13/2026-16515/air-plan-approval-missouri-clean-data-determination-for-the-2015-8-hour-ozone-standard-for-the). Last refreshed: 2026-11-04T09:17:43.641Z.
Data from the Federal Register API; the published Federal Register document is authoritative. Informational only, not legal advice.