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
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.
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)
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