# Approval and Promulgation of Implementation Plan; Indiana
> **Rule** · Final rule. · Published 1998-07-27 · Effective 1998-08-26 · 63 FR 40041
## Document
- **Document number:** 98-19931
- **Category:** air-emissions
- **Federal Register citation:** 63 FR 40041
- **CFR reference:** 40 CFR 52
- **Publication date:** 1998-07-27
- **Effective date:** 1998-08-26
- **State:** IN
- **EPA docket:** IN75
## Abstract

The United States Environmental Protection Agency (USEPA) is approving Indiana's request to grant an exemption for the northwest Indiana (Lake and Porter Counties) severe ozone nonattainment area from the applicable Oxides of Nitrogen (NO<INF>X</INF>) transportation conformity requirements. The USEPA proposed approval on January 6, 1998. The proposal was based on information the Indiana Department of Environmental Management (IDEM) submitted to the USEPA as a State Implementation Plan (SIP) revision request for an exemption under section 182(b)(1) of the Clean Air Act (Act). The technical basis for IDEM's request was the urban airshed modeling (UAM) conducted for an attainment demonstration for the Lake Michigan Ozone Study (LMOS) modeling domain.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1998/07/27/98-19931/approval-and-promulgation-of-implementation-plan-indiana)
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