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 January of 2019, MDOT conducted an air quality conformity analysis for Kent and Ottawa Counties based on the 1997 ozone standard. Conformity areas do not have the same boundaries as MPOs.  All of the GVMC MPO is included in the conformity area, as are parts of the MACC and WestPlan MPOs.  Emissions estimates were generated from the project lists for the documents below:

  • GVMC 2040 LRTP

  • GVMC FY2017-2020 TIP

  • WestPlan 2040 LRTP for projects in Ottawa County

  • WestPlan FY2017-2020 TIP for projects in Ottawa County

  • MACC 2040 LRTP for projects in Ottawa County

  • MACC 2017-2020 TIP for projects in Ottawa County

  • STIP for projects in Ottawa County

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.



The conformity analysis document is subject to public comment. GVMC’s public comment period will run from Wednesday, February 27 – Wednesday, March 20. Please submit comments to Andrea Faber by email, by phone at (616) 776.7603, or online (see below). Comments received will be recognized and considered, and a response provided. On Wednesday, March 20, at the regularly scheduled Policy Committee meeting, the Policy Committee will be asked to make a formal conformity determination, through a resolution, that the findings of the conformity analysis conform to the SIP.  


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 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.