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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.
The EPA has issued a rule
(203 kb) that will govern the review and handling of air quality data influenced by exceptional events. This rule became effective on May 21, 2007.
The new federal exceptional events regulations (40 CFR Part 50.14 (c) (3)(i) requires all relevant flagged data be made available by the State for a 30-day public review and comment period. The following are current exceptional events out for public comment:
| Dates of Flagged Data | Monitor | Value | Pollutant | Type of Exceptional Event: | Event Demonstration | Comment Period |
|---|---|---|---|---|---|---|
| July 4, 2007 | Rose Park | 78.1 μg/m3 | PM2.5 | Fireworks | Available (525 kb) |
November 1- December 1, 2007 |
| July 5, 2007 | West Valley | 50.7 μg/m3 | PM2.5 | Fireworks | Available ( 507 kb) |
November 1- December 1, 2007 |
| July 9, 2007 | Lindon | 44.3 μg/m3 | PM2.5 | Wildfire | Available (2,584 kb) |
November 1- December 1, 2007 |
| July 11, 2007 | Lindon | 42.1 μg/m3 | PM2.5 | Wildfire | Available (1,922 kb) |
November 1- December 1, 2007 |
| July 11, 2007 | Spanish Fork | 46.3 μg/m3 | PM2.5 | Wildfire | Available (1,918 kb) |
November 1- December 1, 2007 |
For more information or questions about meteorology contact : Dave Strohm 536-4015