# Approval and Promulgation of State Implementation Plans; State of Colorado; Interstate Transport of Pollution Revisions for the 1997 8-Hour Ozone and 1997 PM2.5 NAAQS: “Interference With Visibility” Requirement
> **Rule** · Final rule. · Published 2011-04-20 · Effective 2011-05-20 · 76 FR 22036
## Document
- **Document number:** 2011-9580
- **Category:** air-emissions
- **Federal Register citation:** 76 FR 22036
- **CFR reference:** 40 CFR 52
- **Publication date:** 2011-04-20
- **Effective date:** 2011-05-20
- **State:** CO
- **EPA docket:** EPA-R08-OAR-2007-1036
## Abstract

EPA is partially approving the Colorado Interstate Transport State Implementation Plan (SIP) revision, submitted on March 31, 2010, addressing the requirements of Clean Air Act (CAA) section 110(a)(2)(D)(i)(II) for the 1997 ozone National Ambient Air Quality Standards (NAAQS), and the requirements of CAA section 110(a)(2)(D)(i)(I) and (II) for the 1997 PM<INF>2.5</INF> NAAQS. Specifically, in this Federal Register action EPA is fully approving those portions of the Colorado March 31, 2010 submission that address the section 110(a)(2)(D)(i)(II) requirement prohibiting a state's emissions from interfering with any other state's required measures to protect visibility for the 1997 ozone and PM<INF>2.5</INF> NAAQS. This action is being taken under section 110 of the CAA.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2011/04/20/2011-9580/approval-and-promulgation-of-state-implementation-plans-state-of-colorado-interstate-transport-of)
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