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About the Exceptional Events Rule

The Exceptional Events Rule (EER) provides a way for states to flag air quality data for possible exclusion when NAAQS compliance is determined, provided the EPA concurs with the supporting documentation, and the event contributing to the data meets certain criteria. Exceptional Events are those events that impact air quality but are not reasonably controllable, and not likely to reoccur. Wildland fires are among the exceptional events states flag under this rule.

More Information

Exceptional Events Rule Homepage - The EPA's main information page, showing updates, background, and links to other resources.

Exceptional Events Rule Documents - The EPA's page for guidance documents, FAQS, and in-depth EER information.


Exceptional Events Guidance: Prescribed Fire on Wildland that May Influence Ozone and Particulate Matter Concentrations

In August 2019 the EPA released guidance documenting particulate matter or ozone events influenced by prescribed fire or wildland fire. 

Visit the EPA's page to read and download the full document