Environmental Planning

Air Quality

Transportation Conformity

Transportation Conformity ensures that transportation plans, programs and projects do not produce new air-quality violations, worsen existing violations or delay timely attainment of the National Ambient Air Quality Standards (NAAQS).

The ADOT Air Quality Team is responsible for implementing and developing the statutory and regulatory requirements for conformity state implementation plans (conformity SIPs). A conformity SIP includes a state's specific criteria and procedures for certain aspects of the transportation conformity process. Clean Air Act section 176(c) is the statutory authority for transportation conformity (42 U.S.C. 7506(c)). The regulations that explain the requirements for a conformity SIP are found at 40 CFR 51.390, which was updated Jan. 24, 2008 (73 FR 4420). 

Project Level Conformity

Completed PM Project Level Project of Air Quality Concern (POAQC) consultation and/or hot-spot modeling documents will be posted here as applicable.

CO Conformity Determinations
Completed Project Level CO Hot-Spot consultation documents required for hot-spot modeling will be posted here as applicable.

Isolated Rural Area Conformity Documents

ADOT is currently developing a regional conformity analysis in support of the State Route 189 Study: International Border to Grand Avenue project under current study.   This project is in Nogales, which is in nonattainment for the Federal standard for particulate matter less than or equal to 2.5 microns in diameter (PM2.5) and for the particulate matter less than or equal to 10 microns in diameter (PM10).

The U.S. Environmental Protection Agency (EPA) transportation conformity regulations requires certain projects in nonattainment areas to engage in interagency consultation and complete PM2.5/PM10  analyses as part of the project-level conformity determination process.  In rural areas, interagency consultation on regional and project level conformity required for federal funded transportation projects is conducted through the ADOT’s Environmental Planning Air Quality staff.  ADOT submitted a Project of Air Quality Concern Questionnaire for PM2.5 and PM10 Interagency Consultation in December 2016 and held two Interagency Consultation Meetings on February 22nd, and May 25th 2016. It was determined through consultation that the project does not fit the description of a project of air quality concern regarding PM2.5 and PM10 as defined in 40 CFR 93.123(b)(1), this process is described here

Transportation Conformity also requires that FHWA/FTA projects in PM10 and PM2.5 nonattainment and maintenance areas demonstrate that during the time frame of the transportation plan no new local violations will be created and the severity or number of existing violations will not be increased as a result of the project, and the project has been included in a regional emissions analysis that meets applicable §§ 93.118 and/or 93.119 requirements. The demonstration must be performed according to the consultation requirements of § 93.105(c)(1)(i) and the methodology requirements of § 93.123.

ADOT provided the draft Arizona Department of Transportation Air Quality Regional Conformity Analysis Nogales Nonattainment for review and comment through May 22nd , 2017, no comments were received.

Prior Draft Documents include:

MPOs' Conformity Documents
2019 Conformity Finding Letters
2018 Conformity Finding Letters
2017 Conformity Finding Letters
2016 Conformity Finding Letters
2015 Conformity Finding Letters
2014 Conformity Finding Letters
  • Maricopa Association of Governments: 2014-2018 TIP
    Note: Includes projects from SCMPO and Pinal County PM10 and PM2.5 nonattainment areas.
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