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Ozone Nonattainment

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Environment, Great Lakes, and Energy

Ozone Nonattainment


The United States Environmental Protection Agency (USEPA) published ozone nonattainment designations for the 2015 National Ambient Air Quality Standard (NAAQS) with an effective date of August 3, 2018. The Michigan counties designated as nonattainment are Berrien, Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne. In addition, portions of Allegan and Muskegon counties are also designated as nonattainment. Ozone nonattainment areas are classified based on the severity of their ozone concentrations. All areas in Michigan were originally classified as marginal nonattainment, which is the lowest level of classification and means that ozone concentrations are less than 10 parts per billion (ppb) above the standard. Michigan had until August 3, 2021, to bring the design values at or below the 2015 Ozone NAAQS, however, Michigan was not able to attain the standard and will likely be "bumped-up" to a moderate nonattainment classification. This webpage features more information on Michigan's Ozone nonattainment, the Clean Air Act (CAA) requirements for the moderate nonattainment classification, EGLE's timeline, workgroups, and field study. Recent workgroup information is available below. 


Jay Olaguer, Air Quality Division

Marginal Nonattainment Areas

Michigan currently has four areas in Marginal nonattainment. The Clean Air Act requires several responses/actions be taken for areas designated as marginal.

  • Baseline Emission Inventory
  • Nonattainment New Source Review
  • Major Source Emission Statements

Completed submittals are available on the Recent Air Quality Planning Actions and Documents web page.

Moderate Nonattainment Areas

If Michigan does not achieve design values below the 2015 ozone NAAQS standard by 2021, it is possible those areas will be "bumped" to Moderate Nonattainment. This will require additional actions to be taken.

  • VOC / NOx RACT for Major and CTG Sources
  • 15% VOC or 15% VOC / NOx Decrease (over six years)
  • Attainment Demonstration
  • Basic Inspection and Maintenance (for larger population areas:  200,000+ based off 1990 census)
  • Contingency Measures for Failure to Attain
  • NSR offset ratio increases from 1.1:1 for marginal to 1.15:1 for moderate

At this time, preliminary data suggests the standard was not achieved, thus making a "bump up" more likely. EGLE is currently investigating alternative options as discussed below (e.g., 179B, exceptional events).

Ozone Attainment Roadmap


The Air Quality Division is actively working on requirements for upcoming deadlines associated with the 2015 ozone standard. Other activities include planning for a possible moderate classification, a summer ozone study and much more. The Comprehensive 2015 Ozone Attainment Planning Roadmap and Gantt Chart was created to assist us in planning and development. The dates and timeframes contained within will be revised as appropriate when they can be determined.

Also, a major component of Michigan's response to the nonattainment status of these areas may be rule making.  A list of potential new rules was created and is being maintained/updated as part of the planning process.


* Dates subject to change based on USEPA Rules

** Alternatives to moderate classification bump-up involve Exceptional Events and/or 179B(b) demonstrations.

Please note that the planning document was developed before COVID-19 impacted the State of Michigan.

2021 Michigan-Ontario Ozone Source Experiment (MOOSE)

EGLE collaborated with several entities including the Canadian government, NOAA, NASA, USEPA, and the USFS in planning and executing a meteorological field study in the summer of 2021 to help address ozone nonattainment in Southeast Michigan. The study used advanced remote sensing and mobile real-time monitoring in conjunction with high spatial and temporal resolution models to investigate ozone chemistry in the area. The information will be used to determine how much various sources of pollution contribute to Southeast Michigan's ozone values and ultimately to develop an ozone attainment plan for the area. For additional information, see the published article Landfill Emissions of Methane Inferred from Unmanned Aerial Vehicle and Mobile Ground Measurements or contact Jay Olaguer at 517-512-0059.


The following workgroups have been established with the intent of facilitating early discussion of potential control strategies for a moderate nonattainment SIP for the southeast Michigan Ozone nonattainment area:

  • Primary Formaldehyde, VOC / NOx RACT and Landfill Emissions: This workgroup has three interrelated facets. The first is looking at stationary sources of formaldehyde, often formed as a result of combustion of common fuels. The second is is looking at large sources of NOx and VOC within the nonattainment area to assess potential RACT rules. The third is looking at controlling methane from landfills. For additional information, contact Trace McDonald at 517-582-3570 or Marissa Stegman at 517-582-3601.
  • Oil & Gas Emissions: This workgroup is investigating emissions of methane from the oil and gas sectors throughout the state. Work is focusing on quantifying emission reductions that can be used to lower ozone values. For additional information, contact Alec Kownacki at 517-614-6678.
  • Intermodal Transportation Emissions: This workgroup will focus on emissions that are potentially generated from heavy duty trucks, airports, train yards, and boat transport. For additional information, contact Breanna Bukowski at 517-648-6314 or Marissa Stegman at 517-582-3601.
  • Southeast Michigan (SEMI) Modeling and Measurement Steering Committee: This workgroup will make decisions regarding the collection of data that can be used for nonattainment planning. For additional information, contact Jay Olaguer at 517-512-0059.

More Information on Ozone

Permitting Information and Other Topics

Latest Ambient Monitoring Data