# Air Plan Approval; Arizona; Attainment Plan for the Hayden SO2 Nonattainment Area for the 1971 and 2010 Sulfur Dioxide National Ambient Air Quality Standards

**Action Urgency Score:** 30/100

| Field | Value |
|---|---|
| Agency | Environmental Protection Agency |
| Type | Final rule |
| Action | Final rule. |
| Published | 2026-08-20 |
| Effective | 2026-09-21 |
| Significant | No |
| CFR parts | 40 CFR 52 |
| Summary | The Environmental Protection Agency (EPA) is finalizing approval of revisions to the Arizona state implementation plan (SIP) for attaining the 1971 and 2010 sulfur dioxide (SO<INF>2</INF>) national ambient air quality standards (NAAQS or "standards") in the Hayden SO<INF>2</INF> nonattainment area. These SIP revisions, collectively referred to as the "Hayden SO<INF>2</INF> Plan" or "Plan," include Arizona's attainment demonstration and other elements required under Clean Air Act (CAA or "Act") sections 110, 172, 191, and 192. In addition to an attainment demonstration, the revisions address th |
| Document number | 2026-16989 |

## Why this score
- Final rule.

Source: Federal Register API (Office of the Federal Register) (https://www.federalregister.gov/documents/2026/08/20/2026-16989/air-plan-approval-arizona-attainment-plan-for-the-hayden-so2-nonattainment-area-for-the-1971-and). Last refreshed: 2026-11-03T19:10:06.902Z.
Data from the Federal Register API; the published Federal Register document is authoritative. Informational only, not legal advice.