The South Coast Air Quality Management District (SCAQMD) is seeking public comments on the flagging of ambient air quality data influenced by exceptional events. The purpose of this request for public comment is to seek input on whether certain days should be flagged for exclusion from consideration in deciding attainment of the federal clean air standards, primarily for PM10 and PM2.5 particulate matter. The documentation provided below describes exceptional events that contributed to violations of the National Ambient Air Quality Standards (NAAQS). These events can include natural events, such as high winds, volcanic activity and wildfires. The exceptional event rule also allows flagging of data influenced by emissions from fireworks displays associated with national or cultural traditions, such as Independence Day. The following exceptional events documentation is currently available for public comment.
Provides background, procedural requirements and mitigation information related to high wind natural events that contributed to PM10 NAAQS violations on three days in the Coachella Valley in 2008.
The public comment period for the April 30, 2008 analysis has ended.
The public comment period for the May 21, 2008 analysis has ended.
The public comment period for the June 4, 2008 analysis has ended.
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This amended final report for the high wind PM10 natural event at Anaheim on October 13, 2008 addresses language, figures and formatting consistent with U.S. EPA comments and draft exceptional event guidance. No further public review is required, but comments and questions are welcome.
Interested persons may submit comments addressing these events to:
Mr. Kevin Durkee, Senior Meteorologist
Planning, Rule Development & Area Sources
South Coast AQMD
21865 Copley Drive
Diamond Bar, CA 91765
E-mail: kdurkee@aqmd.gov
Background
Since 1977 the United States Environmental Protection Agency (EPA) has implemented policies to address the treatment of ambient air quality monitoring data that has been affected by exceptional or natural events. 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 (i.e., flagging for exclusion from standard compliance consideration) for data affected by natural events (e.g., wildfire, high wind events, and volcanic and seismic activities). Since 1996, EPA has approved several requests made by the South Coast Air Quality Management District (SCAQMD) to apply the 1996 Natural Events Policy in order to flag violations of the 24-Hour PM10 National Ambient Air Quality Standards (NAAQS) in the Coachella Valley for natural events that involved uncontrollable high winds. Air quality has continued to improve through implementation of best available control technologies, required by SCAQMD rules and local government ordinances. SCAQMD also protects the public through the issuance of area-specific air quality forecasts and episode notifications, as well as daily high-wind and windblown dust forecasts and advisories for the Coachella Valley.
On March 14, 2007, EPA promulgated a formal rule, entitled: The Treatment of Data Influenced by Exceptional Events. Exceptional events are unusual or naturally occurring events that can affect air quality but are not reasonably controllable or preventable using techniques that tribal, state or local air agencies may implement in order to attain and maintain the National Ambient Air Quality Standards (NAAQS). These events are flagged in the EPA AIR Quality System (AQS) database as exceptional events. The data remains available to the public but are not counted toward attainment status. A fact sheet and the text of the EPA Exceptional Events Regulation can be found at: http://www.epa.gov/ttn/oarpg/t1/fact_sheets/exeventfinal.html#background.
The EPA rulemaking: (1) ensures that air quality measurements are properly evaluated and characterized with regard to their causes; (2) identifies reasonable actions that should be taken to address the air quality and public health impacts caused by these types of events; (3) avoids imposing unreasonable planning requirements on state, local and tribal air quality agencies related to violations of the NAAQS due to exceptional events; and (4) ensures that the use of air quality data, whether afforded special treatment or not, is subject to full public disclosure and review. This web page addresses the public disclosure and review requirement for exceptional events that occur in the South Coast Air Basin or the Coachella Valley portion of the Salton Sea Air Basin, by presenting detailed documentation of recent events.
The 30-day public comment period has ended for the following exceptional event documents, but they are available for information purposes below.
Analysis of Natural Events Contributing to High PM10 Concentrations in the Coachella Valley in 2007 (PDF, 3.9MB)
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This document evaluates high wind events contributing to PM10 NAAQS violations on March 22 and April 6, 2007 at one station (Indio) in the Coachella Valley.
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A separate Appendix (PDF, 2.3MB) to the above document is available that contains supporting documentation to the March 22, 2007 natural event.
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The public comment period for this analysis has ended.
Analysis of Exceptional Events Contributing to High PM10 Concentrations and the Azusa and Fontana Air Monitoring Stations in the South Coast Air Basin on July 5, 2007 (PDF, 1.5MB)
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This document evaluates the contribution of Independence Day fireworks emissions to PM10 NAAQS violations on July 5, 2007 at two stations (Azusa and Fontana) in the South Coast Air Basin.
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The public comment period for this analysis has ended.
Analysis of Exceptional Events Contributing to a High PM10 Concentrations at the Perris Air Monitoring Station on April 12, 2007 (PDF, 5.8MB)
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This document evaluates a high wind natural event contributing to PM10 NAAQS violations on April 12, 2007 at the Perris in the South Coast Air Basin.
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The public comment period for this analysis has ended.
Analysis of Exceptional Events Contributing to High PM10 Concentrations in the South Coast Air Basin on October 21, 2007 (PDF, 1.2MB)
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This document evaluates a high wind and wildfire natural event contributing to PM10 NAAQS violations on October 21, 2007 at several air monitoring stations in the South Coast Air Basin.
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A separate Appendix (PDF, 3.4MB) to the above document is available that contains supporting documentation to the October 21, 2007 exceptional event.
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The public comment period for this analysis has ended.