The Final 2016 Exceptional Events Rule, Supporting Guidance Documents, Updated FAQs, and Other Rule Implementation Resources

The Exceptional Events Rule, guidance documents, and other implementation resources provided on this page are intended to assist air agencies with the preparation of exceptional events demonstrations. The EPA continues to update and develop documents to facilitate implementation of the 2016 Exceptional Events Rule, including new documents to further assist with the development of demonstrations for specific types of events. We will notify air agencies when we add new implementation resources to this site, and encourage stakeholders to revisit it periodically.

On this page:

• Final 2016 Exceptional Events Rule
• Mitigation Plans
• Guidance Documents and FAQs
• Other EPA-Developed Rule Implementation Documents
• EPA Exceptional Events Webinar Materials
• Online Resources and Tools

Final 2016 Exceptional Events Rule

• Federal Register Notice – Final Revisions to the Exceptional Events Rule

Mitigation Plans

• April 2022: Additional Areas Subject to Mitigation Plan Requirements Under the Exceptional Events Rule
• Mitigation Plan Checklist (pdf) (204.43 KB, 6/28/2023)

Guidance Documents and FAQs

• Prescribed Fire: Prescribed Fire on Wildland that May Influence Ozone and Particulate Matter Concentrations (August 2019)
  • Demonstration Template for Prescribed Fires Occurring on Wildland(s) that May Influence Fine Particulate Matter Concentrations (docx) (78.98 KB) (November 2024)
• High Winds: Guidance on the Preparation of Demonstrations in Support of Requests to Exclude Air Quality Data Influenced by High Wind Dust Events Under the 2016 Exceptional Events Rule (April 2019)
• Data Modification: Clarification Memo on additional Methods, Determinations and Analyses to Modify Air Quality Beyond Exceptional Events (April 2019)
• Stratospheric Ozone: Guidance on the Preparation of Exceptional Events Demonstrations for Stratospheric Ozone Intrusions (November 2018)
  • Forecasting Tools for Stratospheric Ozone Intrusions (PDF)
  • Forecasting Tools for Stratospheric Ozone Intrusions (PPTX) (pptx) (17.73 MB, 11/6/2018)
• Wildfire:
  • PM2.5 Wildland Fire Exceptional Events Tiering Document (pdf) (419.8 KB, 04/30/2024, EPA-457/R-24-001)
  • Wildfire Resource Document (pdf) (6.98 MB, Updated 8/3/2023)
  • Final Guidance on the Preparation of Exceptional Events Demonstrations for Wildfire Events that May Influence Ozone Concentrations(September 2016)
• Updated Exceptional Events Rule FAQs (pdf) (505.63 KB) (November 2024)

Other EPA-Developed Rule Implementation Documents

• Best Practices for Preparation of Multi-Agency Exceptional Events Demonstrations
• 2007 to 2016 Exceptional Events Rule Crosswalk
• EPA Review Technical Support Document Template for Wildfire/Ozone Events
• Fact Sheet – Wildland Fire and Air Quality
• Exceptional Events Training Courses

EPA Exceptional Events Webinar Materials

• Presentation on 2016 Exceptional Events Rule and Final Wildfire/Ozone Guidance from public webinar on September 21, 2016 
• Presentation from April 18, 2018, Webinar on Exceptional Events Mitigation Plans

Online Resources and Tools

EPA provides no endorsement of specific publicly available resources, nor does EPA mandate their use. EPA believes that publicly available tools can provide supporting documentation for one or several of the exceptional event criteria within an air agency exceptional events demonstration, but EPA generally does not believe that links and/or references to these tools constitute a complete demonstration submittal.

• AirNow (see links under the “Fires” tab): Current ozone and PM measurements
• Fire and Smoke Map: Current PM_2.5 measurements, as well as information on fires, smoke plume locations, and special statements about smoke issued by various sources
• AirNowTech: Website for air quality data management analysis and decision support 
• EPA AirData: Provides access to outdoor air quality data collected from state, local and tribal monitoring agencies across the United States
• Western Regional Air Partnership: Exceptional Event Data Resource List (primarily smoke- and fire-related)
• Remote Sensing Information Gateway (RSIG): Allows for quick and easy access to subsets of multi-terabyte environmental datasets, including satellite, modeled, and in-situ sensor data
• Wildland Fire Air Quality Tools Portal: Provides links to the most recent versions of tools produced by the U.S. Forest Service PNW Research Station’s Pacific Wildland Fire Sciences Laboratory in support of the Wildland Fire Air Quality Response Program and wildland fire operations
• University of Utah MESOWEST: Provides access to current and archived weather observations across the United States

EPA Exceptional Events Contact:
Gobeail McKinley
U.S. EPA, Office of Air Quality Planning and Standards
Email: [email protected]
919-541-5246