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Exceptional Events (EE) and Natural Events (NE)

In 2004, United States Environmental Protection Agency (EPA) approved a high wind data flag for a PM10 exceedance that occurred in Corcoran, CA on September 3, 2004. This circumstance led to the development of the Natural Events Action Plan (NEAP) document which was approved by the District Governing Board on February 16, 2006. The purpose of this document was to protect public health in the event of future exceedances caused by natural events such as high winds.  Procedures in the NEAP document were carried out in advance of and during a natural event. The NEAPS written by the District were for high wind events. If other natural events such as wildfires or volcanic eruptions would have occurred, the District would have written a NEAP for each of those events.

In May 2007, EPA adopted the Exceptional Events rule which set the criteria with the process for EPA to agree to exclude event-influenced data when determining compliance with the health based National Ambient Air Quality Standards (NAAQS).  The District now follows this rule which requires documentation after an event-influenced exceedance has occurred.  There are two types of Exceptional Events.  (1) A specific Exceptional Event (EE) is caused by uncontrollable anthropogenic emissions such as structure fires or demolition.  Congress has decided that fireworks associated with cultural events such as July 4th and Chinese New Year celebrations also constitute uncontrollable anthropogenic emissions.  (2) A Natural Event (NE) is caused by natural phenomena such as wind blown dust or volcanic eruptions.  The Exceptional Events rule available at http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=d9815f0d5fd9865c2c7c449433f8bb9f&rgn=div8&view=text&node=40: .

Whenever an EE or NE causes an exceedance, the District prepares a document that deals with the exceedance and the event.  After the event has passed, the District has until July 1 of the following year to notify EPA of the event and three years to submit documentation of the event.  After data from the event has been quality assured and quality controlled, the document is written and posted for public comment.   The District then responds to comments received and makes needed revisions to the document before submitting the document to the California Air Resources Board (CARB) for review.  CARB will either submit the document to EPA for final approval or require further revisions before doing so.   Since 2004, the District has written and submitted a total of eight EE and NE documents to EPA and EPA approved all eight documents.  Additionally, the District has one EE that is pending EPA’s approval, and six EE/NE documents that are in the process of being written.

Links to the District’s completed EEs, and NEs

Information regarding the District's request to flag data from high levels of particulate matter in Corcoran on September 3, 2004 as having been caused by a natural event. Submitted to CARB on March 2, 2005.
Notice of Natural Event Determination

PM10 Natural Event Documentation for September 22, 2006. Submitted to CARB on March 21, 2007.
PM10 Natural Event - September 22, 2006

Addendum dated May 23, 2007

PM10 Natural Event Documentation for October 25, 2006. Submitted to CARB on April 20, 2007.
PM10 Natural Event - October 25, 2006

PM10 Natural Event Documentation for December 8, 2006. Submitted to CARB on May 23, 2007. Revised per CARB request and resubmitted to CARB on June 6, 2007.
PM10 Natural Event - December 8, 2006

PM10 Natural Event December 8, 2006 - Revision dated June 6, 2007

PM10 Exceptional Event Documentation for July 4, 2007. Submitted to CARB on January 16, 2008.
PM10 Exceptional Event - July 4, 2007

PM10 Natural Event Documentation for January 4, 2008. Submitted to CARB on April 10, 2008.
Public Notice

PM10 Natural Event - January 4, 2008

PM2.5 Exceptional Event Documentation for July 4 and 5, 2007. Submitted to CARB on April 10, 2008. (Pending EPA approval) Public Notice

PM2.5 Exceptional Event - July 4 and 5, 2007

PM10 Natural Event Documentation for May 21-22, 2008. Submitted to CARB on August 5, 2008.
Original Notice June 24, 2008

PM10 Natural Event - May 21-22, 2008

Errata (July 7, 2008)

Final version submitted to EPA and CARB on August 7, 2008