# Approval and Promulgation of Air Quality Implementation Plans; Montana; 1990 Base Year Emission Inventories for Montana
> **Rule** · Direct final rule. · Published 1997-12-15 · Effective 1998-02-13 · 62 FR 65613
## Document
- **Document number:** 97-32644
- **Category:** air-emissions
- **Federal Register citation:** 62 FR 65613
- **CFR reference:** 40 CFR 52
- **Publication date:** 1997-12-15
- **Effective date:** 1998-02-13
- **State:** MT
- **EPA docket:** MT-001-0002a, MT-001-0003a
## Abstract

EPA is approving the 1990 base year carbon monoxide (CO) emission inventories for Missoula, Billings, and Great Falls that were submitted by the State to satisfy certain requirements of the Clean Air Act (CAA), as amended in 1990.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1997/12/15/97-32644/approval-and-promulgation-of-air-quality-implementation-plans-montana-1990-base-year-emission)
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