# Air Quality Designations for the 2010 Sulfur Dioxide (SO2) Primary National Ambient Air Quality Standard-Round 4-Supplemental Amendment
> **Rule** · Final rule. · Published 2021-04-14 · Effective 2021-04-30 · 86 FR 19576
## Document
- **Document number:** 2021-07574
- **Category:** air-emissions
- **Federal Register citation:** 86 FR 19576
- **CFR reference:** 40 CFR 81
- **Publication date:** 2021-04-14
- **Effective date:** 2021-04-30
- **EPA docket:** EPA-HQ-OAR-2020-0037
## Abstract

The Environmental Protection Agency (EPA) is withdrawing the initial nonattainment designation for portions of the Outagamie County, Wisconsin, area for the 2010 sulfur dioxide (SO<INF>2</INF>) primary National Ambient Air Quality Standard (NAAQS) and is finalizing a designation of attainment/unclassifiable for the area. The EPA Administrator signed an action on December 21, 2020, to designate certain areas in the United States (U.S.) for the 2010 SO<INF>2</INF> NAAQS, including the Outagamie County area. This action supplements the EPA's December 2020 designations, published in the Federal Register of March 26, 2021, which have not yet taken effect.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2021/04/14/2021-07574/air-quality-designations-for-the-2010-sulfur-dioxide-so2-primary-national-ambient-air-quality)
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