Menu

**We are improving our website to help you find what you're looking for. During this transition some URLs may change.**  **Learn more...**

Related Topics: Air Quality Analysis 

# Treatment of Data Influenced by Exceptional Events **Exceptional Events are unusual or naturally occurring events that can affect air quali ty but are not**  **reasonably controllable using techniques that tribal, state or local air agencie s may implement in**  **order to attain and maintain the National Ambient Air Quality Standards.** Contact: **Mark Evangelista**

**Evangelista.Mark@epa.gov (919) 541-2803**  

### Background **The Environmental Protection Agency (EPA) finalized a rule to establish crite ria and procedures**  **for use in determining if air quality monitoring data has been influenced by exceptional events. The**  **rule: • ensures that air quality measurements are properly evaluated and characte** **rized with regard to their causes,**  **• identifies reasonable actions that should be taken to address the air quality and p ublic health**  **impacts caused by these types of events, • avoids imposing unreasonable planning requirements on state, local, and tribal air**  **quality agencies related to violations of the NAAQS due to exceptional events, and**  **• ensures that the use of air quality data, whether afforded special treatment or not, is subject to**  **full public disclosure and review. In July 2012, EPA issued a**  Federal Register **Notice of Availability announcing the release of draft exceptional events implementation guidance developed to clarify key provisions of the**  **2007 Exceptional Events Rule (EER), respond to questions and issues that arose after the E**  **ER was promulgated, and reduce the burden associated with the demonstration preparation and r** **eview process. After considering the feedback received during the public comment pe**  **riod, EPA has decided to resolve a number of commenter-identified issues and needed clarificati**  **ons in a more formal rulemaking process. Because the notice and comment rulemaking process i**  **s expected to take up to two years to conclude, EPA is issuing the interim guidance.**  **Page 1**  **of 3**  **Treatment of Data Influenced by Exceptional Events | Air Quality Analysis | US EPA** 

**10/ 9/** **2015 http://www2.epa.gov/air**  **- quality**  **- analysis/treatment**  **- data**  **- influenced**  **- exceptional**  **- events** 

### Interim Exceptional Events Guidance Documents (Post ed: 05/13/13)

**• Interim Exceptional Events Guidance Documents**  **◦ Fact Sheet ◦ Interim Guidance to Implement Requirements for the Treatment of Air Qualit** **y Monitoring Data Influenced by Exceptional Events**  ◾ **Attachment 1, Interim Exceptional Events Rule Frequently Asked Questions** ◾ **Attachment 2, Interim Guidance on the Preparation of Demonstrations in Support of Requests to Exclude Ambient Air Quality Data Affected by High**  **Winds under the Exceptional Events Rule** For guidance-related questions, please contact Beth W. Palma at 919-541-5432 or palma.elizabeth@epa.gov 

### Quick-Reference Guide for Exceptional Events Demons trations **This user-friendly quick-reference guide for exceptional events demonstrations**  **is intended to direct air agency staff and other interested persons to specific information and guidance r**  **elated to exceptional events demonstrations. The matrix pairs event and pollutant combinat** **ions (x-axis) with current Exceptional Events Rule criteria (y-axis). Each cell contains links t**  **hat direct the user to specific example analyses or language that may be used in Exceptional Events D**  **emonstrations. EPA expects to update this matrix as additional information (rule revisions, gui**  **dance, demonstrations) become available.**  

### Examples of Reviewed Exceptional Event Submissions **This exceptional events submissions table**  **provides examples of air agency-submitted and EPA concurred exceptional events demonstration packages along with the accompanying EPA**  **concurrence letters and supporting analyses. EPA expects to update this table as additional**  **demonstrations become available.** 

### Best Communication Practices for Preparation of Exc eptional Events Demonstrations **Because of the passage of time between issuing the 2013 Interim Exceptional Event s**  **Implementation Guidance and the EPA’s anticipated 2015 proposed revisions to the E xceptional**  **Events Rule, the EPA hosted conference calls with some air agencies between Se ptember 2014 and**  **March 2015 to ask whether any new exceptional events implementation concerns had arisen and t o**  **better understand currently employed exceptional events implementation proces ses and practices.**  **As a result of these discussions, the EPA developed a list of best practices**  **for communication and collaboration between the EPA and air agencies. The EPA will update this docume** **nt, if needed, to reflect promulgated changes to the Exceptional Events Rule (if needed, revisions ant** **icipated summer 2016).**  

### Publicly Available Support Information and Tools **Page 2**  **of 3**  **Treatment of Data Influenced by Exceptional Events | Air Quality Analysis | US EPA** 

**10/ 9/** **2015 http://www2.epa.gov/air**  **- quality**  **- analysis/treatment**  **- data**  **- influenced**  **- exceptional**  **- events** EPA provides no endorsement of specific publicly available tools, nor does EPA mandate their use.

EPA believes that publicly available tools can provide supporting documentation f or one or several of the exceptional event criteria within an air agency exceptional event demonst ration, but EPA generally does not believe that links and/or references to these tools constitute a c omplete demonstration submittal.

**• Technical Support Document (TSD) Preparation - “best practices and comp**  **onents” presentation**  **• Remote Sensing Information Gateway**  **• Wildland Fire Air Quality Tools Portal**  **• University of Utah MESOWEST**  **• DataFed: Web-based software providing atmospheric data and tools** 

Last updated on September 22, 2015 **Page 3**  **of 3**  **Treatment of Data Influenced by Exceptional Events | Air Quality Analysis | US EPA** 

**10/ 9/** **2015 http://www2.epa.gov/air**  **- quality**  **- analysis/treatment**  **- data**  **- influenced**  **- exceptional**  **- events**