Technology Transfer Network - OAR Policy and Guidance
The Treatment of Data Influenced by Exceptional Events - Final Rule
- On March 14, 2007, the Environmental Protection Agency (EPA) finalized a rule to establish criteria and procedures for use in determining if air quality monitoring data has been influenced by exceptional events such as unplanned fires or destructive storms.
- 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.
- This rule establishes the procedures and criteria that will be used to identify, evaluate, interpret and use monitored air quality data for comparison to the National Ambient Air Quality Standards in situations where state, local, and tribal air quality agencies request special treatment because the data has been affected by an exceptional event.
- This final rule:
- ensures that air quality measurements are properly evaluated and characterized with regard to their causes,
- identifies reasonable actions that should be taken to address the air quality and public 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.
- Since 1977, EPA has implemented policies to address the treatment of air quality data that has been affected by exceptional or natural events.
- In 1986, EPA developed a guidance document entitled "Guideline On the Identification and Use of Air Quality Data Affected by Exceptional Events" which provided the criteria and procedures that states should use to flag data for special treatment.
- In 1990, Congress amended the Clean Air Act to give special consideration to areas that are influenced by natural sources of air pollution. Section 188(f), of Part D, Subpart IV related to PM-10 State Implementation (SIP) measures, provided EPA the authority to waive specific SIP requirements, or the attainment date for an area, where the area is affected by natural sources of air pollution.
- In 1996 EPA developed a guidance document entitled "Areas Affected by PM-10 Natural Events", which provided criteria and procedures for States to request special treatment for data affected by natural events such as wildfire, volcanic and seismic activities, and high wind events.
- In 1998, EPA developed a guidance document entitled "The Interim Air Quality Policy On Wildland and Prescribed Fires" which provided criteria and procedures for States to address emissions related to fires set for resource benefits.
- In 2005, Congress promulgated SAFE-TEA-LU, which requires EPA to propose and then finalize a rulemaking action which identifies the criteria and procedures that States should follow to get data excluded from regulatory consideration that has been determined to be affected by an exceptional event.
- This final rule may be found at EPA's website at https://www3.epa.gov/ttn/oarpg/t1pfpr.html.
- In addition to this final rulemaking action, other background information is available at www.regulations.gov or in hardcopy at:
EPA's Air and Radiation Docket and Information Center,
Environmental Protection Agency, Room B102,
1301 Constitution Avenue, NW,
The docket ID No. is OAR-2005-0159. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744. The number for the Air and Radiation Docket and Information Center is (202) 566-1742.
- For further information concerning this action, contact Mr. Larry D. Wallace, Ph.D. of EPA's Office of Air Quality Planning and Standards at (919) 541-0906.