# Air Plan Approval and Disapproval; Colorado; Serious Attainment Plan Elements and Related Revisions for the 2008 8-Hour Ozone Standard for the Denver Metro/North Front Range Nonattainment Area
> **Rule** · Final rule. · Published 2023-11-07 · Effective 2023-12-07 · 88 FR 76676
## Document
- **Document number:** 2023-24230
- **Category:** air-emissions
- **Federal Register citation:** 88 FR 76676
- **CFR reference:** 40 CFR 52
- **Publication date:** 2023-11-07
- **Effective date:** 2023-12-07
- **State:** CO
- **EPA docket:** EPA-R08-OAR-2023-0272
## Abstract

The Environmental Protection Agency (EPA) is approving portions and disapproving portions of a state implementation plan (SIP) revision submitted by the State of Colorado to meet Clean Air Act (CAA) requirements for the 2008 8-hour ozone national ambient air quality standards (NAAQS) in the Denver Metro/North Front Range nonattainment area (DMNFR Area). Specifically, the EPA is approving the submitted enhanced monitoring SIP element as meeting applicable Serious area requirements for the 2008 8-hour ozone NAAQS, and is disapproving the contingency measure element of the SIP submittal. The EPA is taking this action pursuant to the CAA.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2023/11/07/2023-24230/air-plan-approval-and-disapproval-colorado-serious-attainment-plan-elements-and-related-revisions)
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