Grand Valley Metro Council

Air Quality

Air Quality Conformity


Transportation conformity provisions of the Clean Air Act Amendments require metropolitan planning organizations (MPOs) to make a determination that the Long Range Transportation Plan (LRTP), Transportation Improvement Program (TIP), and the projects conform to the State Implementation Plan (SIP) and that regional emissions will not negatively impact the region’s ability to meet the National Ambient Air Quality Standards (NAAQS).

Conformity to the SIP means that the region’s LRTPs and TIPs 1) will not cause any new violations of the NAAQS; 2) will not increase the frequency or severity of existing violations; and 3) will not delay attaining the NAAQS.

In March of 2019, MDOT conducted an air quality conformity analysis for Kent and Ottawa Counties based on the 1997 ozone standard. Projects in the 2040 LRTPs have not changed since the previous air quality conformity analysis conducted in January 2019 and are included in the modeling but not in the project lists. Projects evaluated for this analysis include:

  • GVMC’s 2020-2023 TIP

  • WestPlan’s  2020-2023 TIP projects in Ottawa County

  • MACC’s 2020-2023 TIP projects in Ottawa County

  • The State Transportation Improvement Program (STIP) in Kent and Ottawa counties

The staff of the GVMC, WestPlan, and MACC find that the LRTPs and TIPs conform to the SIP for the 1997 ozone standard based on the results of the conformity analysis.

Conformity is demonstrated when the analysis-year emissions are equal to or less than the SIP budget (see below). The emissions results for the analysis years show that the volatile organic compounds (VOC) and nitrogen oxides (NOx) emissions are lower than the SIP budgets; thus, conformity for the ozone standard is demonstrated.

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Consultation with federal, state, and local transportation authorities is conducted through the Michigan Transportation Conformity Interagency Workgroup (MITC-IAWG). Issues discussed include evaluating and choosing emission models and methods, determining regionally significant project definition, procedures for future MITC-IAWG meetings, and rules for reviewing projects.

For more information, please see the project lists from the FY2017-2020 TIP, FY2020-2023 TIP, and 2040 MTP (GVMC’s Long Range Transportation Plan), which have been evaluated by the MITC-IAWG Committee. Please note that the project lists include whether projects are air quality exempt or non-exempt.  

The MITC-IAWG Committee evaluates all TIP and LRTP amendments to determine if projects are air quality exempt, meaning they do not have to be included in a conformity analysis, or if a project is non-exempt, meaning it has to be included in a conformity analysis. The GVMC Technical and Policy Committees also approve TIP and LRTP amendments at their regularly scheduled meetings. For a committee meeting schedule, please click here.  To view Technical and Policy Committee agendas, please visit our Committee Meetings and Agendas page.    


Please visit the West Michigan Clean Air Coalition’s web page for detailed information about the history of air quality in West Michigan.

For more information about the TIP, please click here.

For more information about the MTP, please click here.

If you have questions about the air quality conformity document, please email Andrea Faber or call 616.776.7603.