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

**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 Illinois portion of the St. Louis, MO- IL nonattainment area (hereafter also referred to as the "St. Louis area" or "area") has achieved clean data for the 2015 ozone National Ambient Air Quality Standards (NAAQS or standard). This determination is based upon complete, quality-assured, and certified ambient air monitoring data for the 2023-2025 design value period showing that the Illinois portion of the area achieved attainment of the 2015 ozone NAAQS. This determination also relies on the EPA's co |
| Document number | 2026-16514 |

## Why this score
- Final rule.

Source: Federal Register API (Office of the Federal Register) (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). Last refreshed: 2026-11-04T21:40:49.974Z.
Data from the Federal Register API; the published Federal Register document is authoritative. Informational only, not legal advice.