PUBLIC NOTICE | Exceptional Events in the Maricopa County PM10 Nonattainment Area

ADEQ is soliciting comments on its final demonstration of an event that has caused elevated concentrations of PM10 in the Maricopa County (Greater Phoenix) PM10 Nonattainment area on 4/25/16, 5/27/16, 7/29/16, 9/27/16, 9/28/161. ADEQ has decided to flag these episodes based on this analysis.

In 2005, Congress identified a need to account for events that result in exceedances of the National Ambient Air Quality Standards (NAAQS) that are exceptional in nature (e.g., not expected to reoccur or caused by acts of nature beyond man-made controls.)  In response, EPA promulgated the Exceptional Events Rule (EER) to address exceptional events in 40 Code of Federal Regulations Parts 50 and 51 on March 22, 2007 (72 FR 13560).  On Oct. 3, 2016, EPA released final revisions to the exceptional events rule. The EER allows for states and tribes to “flag” air quality monitoring data as an exceptional event. If flagged, these data can be excluded from consideration in air quality planning if EPA concurs with the demonstration submitted by the flagging agency documenting that all procedural and technical requirements have been met.

Review Documents

Original Published Public Notice | View/Print >
Exceptional Event Documentation of High Wind Dust Event PM10 Exceedances on April 25, 2016 | View >
Exceptional Event Documentation of High Wind Dust Event PM10 Exceedances on May 17, 2016 | View >
Exceptional Event Documentation of High Wind Dust Event PM10 Exceedances on July 29, 2016 | View >
Exceptional Event Documentation of High Wind Dust Event PM10 Exceedances on Sept. 27 – 28, 2016 | View >

Public Comment Period 

Dates: July 31, 2017 – Aug. 31, 2017

Comments may be submitted as follows:
     Email | Send Email > 
     Mail (Must be postmarked or received by Aug. 31 2017):

       ADEQ
       Air Assessment Section
       1110 W. Washington Street, 3415A-1
       Phoenix, AZ  85007 

Documents may also be reviewed in person at the ADEQ Record Center | Learn More >