Air Quality, Exposure & Monitoring

Section 4 describes air quality monitoring in Detroit conducted by the Michigan Department of Environmental Quality (MDEQ) and others.  It describes, for key pollutants, the monitoring network, concentration trends, and attainment with the National Ambient Air Quality Standards (NAAQS).  These standards are intended to be health protective.  From a regulatory and political perspective, exceedance of the NAAQS, called non-attainment, can greatly increase the awareness of and attention to air pollution problems.  Given their importance in Detroit, the Resource Manual focuses on O3, PM2.5, and SO2.

  • O3 trends suggest a decrease in levels in Detroit since 2002, but current levels are fluctuating around the new (2015) and recently-lowered NAAQS. O3 levels are fairly similar across Detroit; the Allen Park monitoring site currently shows the highest concentrations in the region.  Detroit (like many other urban areas) may exceed the new O3 standard, and significant reductions in precursor NOx and VOC emissions that form O3 may be required if O3 levels do not attain the NAAQS (to be determined in Fall, 2016).
  • PM5 trends have been downward since 1995 at many monitoring sites, however, results differ from site-to-site, and trends are less apparent and even “flat” in more recent years and at industrial sites. Monitors located in Dearborn and at Southwestern High School record among the highest levels in the area.

The very high SO2 levels seen in the 1980s have decreased considerably, but SO2 levels in portions of Wayne County do not meet the most recent (2010) NAAQS.  The region contains a number of major and poorly controlled SO2 sources.  SO2 monitoring is limited, although several sites have been recently added around the Marathon Refinery.  (See map of monitoring sites.)  Unlike O3 and PM2.5, SO2 forms localized “hotspots,” typically near the larger sources like coal-fired power plants and steel mills.  The SO2 non-attainment region is shown in Figure XX (1).  A proposed State Implementation Plan (SIP) for SO2 was released by MDEQ in August, 2015 (2);  an updated plan, which incorporated comments from the public and US EPA, was submitted to US EPA for final approval in May 2016 (3) ; this plan is designed to bring areas into compliance with the NAAQS.

1. Michigan Department of Environmental Quality. 2016. Public Participation Documents for DTE Electric Company Trenton Channel Power Plant, March 9, 2016. Available: [accessed 2 May 2016]

2. Michigan Department of Environmental Quality. 2015 Proposed Sulfur Dioxide One-Hour National Ambient Air Quality Standard State Implementation Plan, August 20, 2015.Available: [accessed 2 May 2016]

3. Michigan Department of Environmental Quality, 2016. Sulfur Dioxide One-Hour National Ambient Air Quality Standard Nonattainment State Implementation Plan for Wayne County (partial). Lansing, MI. Available: [accessed 11 September 2016]



Contact CAPHE

Alison Walding
Project Manager
Community Action to Promote Healthy Environments

University of Michigan School of Public Health
1415 Washington Heights
Ann Arbor, MI 48109-2029