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 Exceptional Event Information


Ambient air quality can be affected by many circumstances. Depending on the parameter measured at a site, the values can be affected by sources (mobile and stationary), activities (human and natural), and weather, occurring either nearby or some distance from that particular location. Many activities can be controlled, altered, or regulated in some manner in order to improve air quality. Other activities affecting air quality are outside the scope of regulation.

A mechanism is set up through EPA for reviewing the data affected by either uncontrollable or non-preventable activities. Data which are in exceedance of a National Ambient Air Quality Standard (NAAQS) are analyzed to determine if they are affected by events which meet this "exceptional event" criteria. If Pinal County Air Quality determines that data may have been affected by an "exceptional event", the data and circumstances are investigated. The county may then flag the data in the Air Quality System (AQS) as being affected by an "exceptional event". The information is submitted to EPA annually for concurrence. If EPA does concur with the county's determination, the data flag is then finalized. The documentation is made available for review to the public throughout the year within the Exceptional Event's page. Comments are accepted during the Public Comment period (30 days) that will be posted within the Public Notice page of the Exceptional Events.

An "exceptional event" is defined by EPA as an event that:

1. Affects air quality
2. Is not reasonably controllable or preventable
3. Is an event caused by human activity that is unlikely to recur at a particular location or a  natural event; and
4. Is determined by EPA through the process established in the regulations, 40 CFR Part 50.14.

Some examples of natural events causing an exceptional event include:

1. High winds
2. Volcanic eruptions
3. Certain fires
4. Seismic activity

Some examples of exceptional events caused by human activity include:

1. Prescribed fires
2. Fireworks
3. Clean up after a major natural disaster

If you have any questions, please e-mail scott.dibiase@pinalcountyaz.gov or call (520) 866-6929.

 Exceptional Events 2018

Sort by AttachmentsUse SHIFT+ENTER to open the menu (new window).
1/9/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)344 ug/m3PM10Cold Front (Max. wind speed 33 mph)
1/9/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)266 ug/m3PM10Cold Front (Max. wind speed 33 mph)
1/9/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)181 ug/m3PM10Cold Front (Max. wind speed 33 mph)
1/9/18Use SHIFT+ENTER to open the menu (new window).
Maricopa (04-021-3010)164 ug/m3PM10Cold Front (Max. wind speed 33 mph)
2/19/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)417 ug/m3PM10Cold front (Max. wind 36 mph)
2/19/18Use SHIFT+ENTER to open the menu (new window).
Eloy (04-021-3014)166 ug/m3PM10Cold front (Max. wind 36 mph)
2/19/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)189 ug/m3PM10Cold front (Max. wind 36 mph)
4/12/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)1,100 ug/m3PM10Cold front (max. wind 47 mph)
4/12/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)780 ug/m3PM10Cold front (max. wind 47 mph)
4/12/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)451 ug/m3PM10Cold front (max. wind 47 mph)
4/12/18Use SHIFT+ENTER to open the menu (new window).
Combs (04-021-3009)365 ug/m3PM10Cold front (max. wind 47 mph)
4/12/18Use SHIFT+ENTER to open the menu (new window).
Eloy (04-021-3014)355 ug/m3PM10Cold front (max. wind 47 mph)
4/12/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)244 ug/m3PM10Cold front (max. wind 47 mph)
4/19/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)829 ug/m3PM10Cold Front (Max. wind 37 mph)
4/19/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)205 ug/m3PM10Cold Front (Max. wind 37 mph)
4/19/18Use SHIFT+ENTER to open the menu (new window).
Eloy (04-021-3014)180 ug/m3PM10Cold Front (Max. wind 37 mph)
4/19/18Use SHIFT+ENTER to open the menu (new window).
Maricopa (04-021-3016)169 ug/m3PM10Cold Front (Max. wind 37 mph)
4/19/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)160 ug/m3PM10Cold Front (Max. wind 37 mph)
4/19/18Use SHIFT+ENTER to open the menu (new window).
Combs (04-021-3009)160 ug/m3PM10Cold Front (Max. wind 37 mph)
5/11/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)386 ug/m3PM10Upper Low (Max. wind 36 mph)
5/11/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)374 ug/m3PM10Upper Low (Max. wind 36 mph)
5/11/18Use SHIFT+ENTER to open the menu (new window).
Eloy (04-21-3014)314 ug/m3PM10Upper Low (Max. wind 36 mph)
5/11/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)276 ug/m3PM10Upper Low (Max. wind 36 mph)
5/11/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)275 ug/m3PM10Upper Low (Max. wind 36 mph)
5/11/18Use SHIFT+ENTER to open the menu (new window).
Combs (04-021-3009)234 ug/m3PM10Upper Low (Max. wind 36 mph)
5/11/18Use SHIFT+ENTER to open the menu (new window).
Apache Junction (04-021-3002)205 ug/m3PM10Upper Low (Max. wind 36 mph)
7/5/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)631 ug/m3PM10Outflow winds (43 mph)
7/5/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)403 ug/m3PM10Outflow winds (43 mph)
7/5/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)398 ug/m3PM10Outflow winds (43 mph)
7/5/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)299 ug/m3PM10Outflow winds (43 mph)
7/6/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)261 ug/m3PM10Pressure gradient (29 mph)
7/6/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)193 ug/m3PM10Pressure gradient (29 mph)
7/8/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)664 ug/m3PM10Outflow winds (55 mph)
7/8/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)516 ug/m3PM10Outflow winds (55 mph)
7/8/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)489 ug/m3PM10Outflow winds (55 mph)
7/8/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)227 ug/m3PM10Outflow winds (55 mph)
7/8/18Use SHIFT+ENTER to open the menu (new window).
Eloy (04-021-3014)182 ug/m3PM10Outflow winds (55 mph)
7/8/18Use SHIFT+ENTER to open the menu (new window).
Apache Junction (04-021-3002)173 ug/m3PM10Outflow winds (55 mph)
7/9/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)607 ug/m3PM10Outflow winds (42 mph)
7/9/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)212 ug/m3PM10Outflow winds (42 mph)
7/9/18Use SHIFT+ENTER to open the menu (new window).
Eloy (04-021-3014)195 ug/m3PM10Outflow winds (42 mph)
7/9/18Use SHIFT+ENTER to open the menu (new window).
Apache Junction (04-021-3002)189 ug/m3PM10Outflow winds (42 mph)
7/30/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)466 ug/m3PM10Outflow winds (Max. wind 36 mph)
7/30/18Use SHIFT+ENTER to open the menu (new window).
Maricopa (04-021-3016)196 ug/m3PM10Outflow winds (Max. wind 36 mph)
8/1/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)326 ug/m3PM10Outflow winds (Max. wind 36 mph)
8/1/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)184 ug/m3PM10Outflow winds (Max. wind 36 mph)
8/2/18Use SHIFT+ENTER to open the menu (new window).
Apache Junction (04-021-3002)503 ug/m3PM10Outflow winds (Max. wind 60 mph)
8/2/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)403 ug/m3PM10Outflow winds (Max. wind 60 mph)
8/2/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)331 ug/m3PM10Outflow winds (max. wind 60 mph)
8/7/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)304 ug/m3PM10Outflow winds (Max. wind 40 mph)
8/7/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)272 ug/m3PM10Outflow winds (Max. wind 40 mph)
8/7/18Use SHIFT+ENTER to open the menu (new window).
Maricopa (04-021-3016)243 ug/m3PM10Outflow winds (Max. wind 40 mph)
8/7/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)165 ug/m3PM10Outflow winds (Max. wind 40 mph)
8/8/18Use SHIFT+ENTER to open the menu (new window).
Maricopa (04-021-3016)658 ug/m3PM10Outflow winds (Max. wind 38 mph)
8/8/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)217 ug/m3PM10Outflow winds (Max. wind 38 mph)
8/8/18Use SHIFT+ENTER to open the menu (new window).
Eloy (04-021-3014)172 ug/m3PM10Outflow winds (Max. wind 38 mph)
8/9/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)355 ug/m3PM10Outflow winds (Max. wind 74 mph)
8/9/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)324 ug/m3PM10Outflow winds (Max. wind 74 mph)
8/9/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)253 ug/m3PM10Outflow winds (Max. wind 74 mph)
8/9/18Use SHIFT+ENTER to open the menu (new window).
PCH (04-021-3011)181 ug/m3PM10Outflow winds (Max. wind 74 mph)
8/9/18Use SHIFT+ENTER to open the menu (new window).
Eloy (04-021-3014)164 ug/m3PM10Outflow winds (Max. wind 74 mph)
8/10/18Use SHIFT+ENTER to open the menu (new window).
Maricopa (04-021-3016)319 ug/m3PM10Outflow winds (Max. wind 40 mph)
8/10/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)314 ug/m3PM10Outflow winds (Max. wind 40 mph)
8/10/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)197 ug/m3PM10Outflow winds (Max. wind 40 mph)
8/12/18Use SHIFT+ENTER to open the menu (new window).
Stanfield (04-021-3008)293 ug/m3PM10Outflow winds (Max. wind 55 mph)
8/12/18Use SHIFT+ENTER to open the menu (new window).
Maricopa (04-021-3016)348 ug/m3PM10Outflow winds (Max. wind 55 mph)
8/12/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)320 ug/m3PM10Outflow winds (Max. wind 55 mph)
8/20/18Use SHIFT+ENTER to open the menu (new window).
Hidden Valley (04-021-3015)210 ug/m3PM10Outflow winds (Max. wind 44 mph)
8/22/18Use SHIFT+ENTER to open the menu (new window).
Casa Grande (04-021-3001)177 ug/m3PM10Outflow winds (Max. wind 28 mph)

 Past Years Exceptional Events

2017 Exceptional Events
{Pending EPA Approval}
2016 Exceptional Events
{Pending EPA Approval}
2015 Exceptional Events
{Pending EPA Approval}
2014 Exceptional Events
{Pending EPA Approval}
2013 Exceptional Events
{Pending EPA Approval}
2012 Exceptional Events
{Pending EPA Approval}
2011 Exceptional Events
{Pending EPA Approval}
2010 Exceptional Events
{Pending EPA Approval}
2009 Exceptional Events
{Pending EPA Approval}
2008 Exceptional Events
{Pending EPA Approval}
2007 Exceptional Events
{Pending EPA Approval}
 

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