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Division of Planning
Office of Environmental Services
Environmental Policy

Air Quality

Projects listed on the STIP and/or TIP are required to have Mobile Source Air Toxics (MSAT), Particulate Matter (PM2.5), and Ozone (O3) addressed under NEPA. The OES-Noise and Air Quality Unit provides guidance that is necessary to ensure that transportation projects are in compliance with the Clean Air act, Transportation Conformity, and NEPA relative to air quality issues. All required air quality analyses must be conducted and coordinated, as necessary, prior to NEPA approval. All air quality analyses are prepared by the District offices or their consultant and forwarded to the OES-Noise and Air Quality Unit for review and coordination as necessary. The OES-Noise and Air Quality Unit provides assistance in determining what level of air quality analysis is required on a project and, in some cases, conducts the required air quality analysis on specific projects when workload permits. The OES-Noise and Air Quality Unit is also responsible for coordinating air quality analyses with the FHWA, OEPA, and USEPA, as necessary. The OES-Noise and Air Quality Unit also advises local transportation project sponsors of the air quality analysis requirements of their projects. Local project sponsors are then required to conduct the required air quality analyses prior to NEPA approval. One copy of an air quality analysis report is required for OES-Noise and Air Quality Unit review.

Guidance on Project-Level Air Quality Analysis Requirements

Relative to Mobile Source Air Toxics (MSATs), an MSAT analysis is required for any project that has sensitive land uses within approximately 500' of the project area and the project involves adding capacity, adding a new interchange, constructing a new road on new alignment, relocating travel lanes closer to sensitive areas, or expanding an intermodal center.

Relative to a Particulate Matter (PM2.5) analysis, if a project is not in a PM2.5 nonattainment or maintenance area, no further PM2.5 analysis is required. A PM2.5 Hotspot Analysis is required if a project is located in a PM2.5 nonattainment or maintenance area and the project's design year ADT >= 125,000 AND the design year diesel truck volume >= 10,000 AND there is significant increase in diesel truck volume between design year build and design year no build conditions. If a project is in a PM2.5 nonattainment or maintenance area but a PM2.5 Hotspot Analysis is not required, then the project is either exempt from air quality conformity for PM2.5 per 40CFR93.126 or the project will require Interagency Consultation with OEPA, USEPA, and FHWA prior to NEPA approval. The OES-Noise and Air Quality Unit is responsible for performing the interagency consultation by project batch approval or project specific approval.

Relative to Ozone, it should be documented if the project is located in an Ozone nonattainment area or not. If a project is listed in the STIP/TIP, then ozone is addressed. However, it must be confirmed that the project scope and description has not changed in the NEPA document since the STIP/TIP listing.

Legislation Section 1796 of The National Clean Air Act is part of a Federal Law that requires NEPA integration. When a proposed Federal Action (i.e. New or Expanded Roadway, Interchange , etc.) could potentially interfere with Clean Air Standards under The Clean Air Act, ODOT with the assistance of the local MPO is required to conduct a special Air Quality analysis to determine the likehood and extent of such interference. This analysis is known as a "Conformity Analysis" and must adhere to specific evaluation protocols established by the Ohio EPA and USEPA. The Federal Highway Administration will not support or fund any highway project that doesn't conform to an approved State Implementation Plan (SIP). No local Metropolitan Planning Organization (MPO) may approve any Transportation project that doesn't conform to an approved SIP. Furthermore, no MPO may adopt or approve a Transportation Improvement Program (TIP) that does not follow the requirements of the 1990 Clean Air Act amendments.


 Guidelines & Documents

Air Quality Transportation Conformity Refresher Workshop Slides


Updated Interim Guidance on Mobile Source Air Toxic Analysis in NEPA Documents, October 18, 2016
PM2.5 Conformity Process Flowchart REVISED
EPA Transportation Conformity Guidance for Qualitative Hot-Spot Analyses in PM2.5 and PM10 Non-attainment and Maintenance Areas
Clean Air Act
Technical Guidance for Analysis of Mobile Source Air Toxics
Ozone Process Flowchart
MSAT Analysis Flowchart
PM2.5 Technical Guidance for Qualitative Hot Spot

 Related Links

Ozone Non-Attainment Areas in OhioWeb
National Ambient Air Quality StandardsWeb
PM2.5 FAQsWeb
PM2.5 Basic InformationWeb
PM2.5 Nonattainment and Maintenance Areas- Annual StandardWeb
The Bridge to Cleaner Air: Transportation ConformityPDF
PM2.5 Nonattainment and Maintenance Areas- 24-Hour StandardWeb