Detroit Clean Data Determination for the 2015 Ozone Air Quality Standard
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Overview
U.S. Environmental Protection Agency is finalizing a clean data determination, originally proposed on February 3, 2023 for the Detroit metropolitan area concluding that the area has monitored attainment of the health-based air quality standard for ground level ozone, or smog. This determination is based on an analysis from the Michigan Department of Environment, Great Lakes and Energy (EGLE) that high ozone values in June 2022 were caused by wildfires. EPA’s response to public comments is addressed in the final rulemaking, which is now being finalized as proposed.
EPA scientists reviewed and concurred with EGLE’s analysis, which relied on meteorological data, modeling of air mass trajectories, comparisons to historical data, and measurements of brown carbon and black carbon, or soot. Because natural wildfires are not reasonably controllable or preventable, and because EPA scientists identified a clear causal relationship between the wildfires and the monitored smog values, EPA determined that EGLE has satisfied all requirements to exclude the data recorded on June 24 and 25, 2022. Under EPA rules, wildfire impacts may be excluded when calculating attainment of the ozone standard.
The air quality data now show that the Detroit metro area meets the federal smog standard. Air quality that shows attainment of the standard is one of the requirements for areas to receive formal air quality “attainment” status under the Clean Air Act.
Clean Data Determination
- Fact Sheet: EPA to Finalize 2015 Ozone Standard Clean Data Determination for the Detroit Metro Area
- Notice of Proposed Rulemaking – Clean Data Determination
- Notice of Final Rulemaking - CDD
Additional Resources
- Notice of Final Rulemaking – Reclassification
- Notice of Proposed Rulemaking - Reclassification
- Detroit Ozone Redesignation to Attainment
- Detroit Ozone Reclassification to Moderate (pdf)
- Ozone Designations Regulatory Actions
- 2015 Ozone National Ambient Air Quality Standards Nonattainment Actions
- Implementation of the 2015 National Ambient Air Quality Standards (NAAQS) for Ozone: State Implementation Plan (SIP) Requirements