Clean Air Act Conformity: the link between Air Quality and Transportation Planning

The air quality conformity determination establishes the compatibility between the state implementation plan, the regional transportation plan, and the transportation improvement program. The transportation plan includes the region’s guide for transportation system development over twenty years. The Transportation Improvement Program (TIP) includes the region’s choices for Federal spending on expansion and preservation of the transportation system over four to five years. The State Implementation Plan (SIP) includes strategies for attaining and maintaining the National Ambient Air Quality Standards (NAAQS). The conformity determination is based on a regional emissions analysis demonstrating compatibility among these three planning documents.

Contact sweber@nirpc.org for information on alternate formats.

• Air Quality Conformity Determination for NWI 2050+ and FYs 2024-2028 TIP
• NIRPC Resolution 25-02 Air Quality Conformity Determination for NWI 2050+ Amendment No. 1 and the 2024-2028 TIP Amendment No. 24-05 with respect to Ozone.
• Air Quality Conformity Determination Report for NWI 2050+ and FYs 2026-2030 TIP (approved by FHWA July 18, 2025)

Vehicle Emissions Educational Event (2/7/2020) Presentations:

• Indiana Department Environmental Management –  Emission Testing Educational Event Presentation
• NIRPC’s Roles in Emissions Testing presentation