PUBLIC NOTICE | Exceptional Events in the Maricopa County (Greater Phoenix) Ozone Nonattainment Area

ADEQ is soliciting comments on its final demonstration of an event that has caused elevated concentrations of Ozone (O3) in the Maricopa County (Greater Phoenix) O3 Nonattainment area on July 7, 2017. Additionally, ADEQ is soliciting comments on its final addendum to the previously submitted demonstration for the event on June 20, 2015. ADEQ has decided to flag exceedance concentrations based on these analyses.
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 CFR Parts 50 and 51 on March 22, 2007 (72 FR 13560). On November 20, 2015, EPA released guidance on the preparation of exceptional events demonstrations for wildfire events that may influence ozone concentrations to State, tribal and local air agencies for review. 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>
Exceptional Event Documentation of ozone (O3) Exceedances on July 7, 2017 | View>
Addendum to Exceptional Event Documentation of Ozone (O3) Exceedances on June 20, 2015 | View>
Original Exceptional Event Documentation of Ozone (O3) Exceedances on June 20, 2015 | View>
Call for Comments
Comment Period: May 17 – June 15, 2018

Submit Comment

Comments can be submitted as follows: 
Mail (Must be postmarked by June 15, 2018):
      Air Assessment Section
      Arizona Department of Environmental Quality
      1110 W. Washington Street, 3415A-1
      Phoenix, AZ 85007
Documents may also be reviewed in person at the ADEQ Record Center | Learn More>