Exceptional events are unusual or naturally occurring events that can affect air quality but are not reasonably controllable using techniques tribal, state or local air agencies may implement in order to attain and maintain the National Ambient Air Quality Standards. Exceptional events are events for which the normal planning and regulatory process established by the Clean Air Act (CAA) is not appropriate.
One type of exceptional event is a natural event. EPA defines a “natural event” as an event in which human activity plays little or no direct causal role to the event in question. For example, a natural event could include such things as high winds, wild fires, and seismic/volcanic activity. Federal regulations (40 Code of Federal Regulations Part 50.14 (b)(2) also allow states to exclude data from regulatory determinations on a case-by-case basis for monitoring stations whose exceedances or violations are caused by emissions from fireworks displays.
- View the EPA’s Exceptional Events rule.