Exceptional Events

There are occasional instances where a natural and exceptional occuring event impacts monitoring, causing a reading that is in exceedance with the National Ambient Air Quality Standards (NAAQS). This is called an Exceptional Event. 

In the case that this occurs, the Final “Treatment of Data Influenced by Exceptional Events” Rule (40 CFR 50.14) allows the state to request a data flag and justify the flag by submitting documentation showing that NAAQS exceedance would not have occurred in the absence of a natural/exceptional event.  

From the files below, you may access the Exceptional Event packets on public notice or submitted to United States Environmental Protection Agency (EPA) Region 8 since 2012.

Public Comments and Contact Information

Members of the public have the opportunity to comment on Exceptional Events. Please note that all comments must be sent by mail, fax, or DEQ's electronic comment portal, and they must be received prior to the comment due date listed next to each event. 

Please address all comments to:

Ms. Cara Keslar
Monitoring Section Supervisor 
200 W. 17th Street 
Cheyenne, WY 82002 

Comments may also be submitted online by going to the following address: 

Additionally, if you would like to access packets submitted prior to 2012, please send an email request to cara.keslar@wyo.gov.  

We will update this page annually to show only the last 3 years of exceptional event packages.

Exceptional Events Currently Out for Public Comment

There are no Exceptional Events Demonstrations currently out for public comment.


File Date