On May 23, 2016, the Arizona Department of Environmental Quality (ADEQ) held a stakeholder meeting to address the proposed boundaries for ozone nonattainment area designations within the state, specifically focused on Maricopa County, Pinal County, and Gila County.  The designations are proposed in accordance with the 2015 National Ambient Air Quality Standard (NAAQS) for ground-level ozone, which decreased the ozone NAAQS from 75 parts per billion (ppb) to 70 ppb.

ADEQ is proposing four separate options for designating Maricopa County, Pinal County, and Gila County.  The proposal is based on the Queen Valley and Gila ambient monitoring stations and the methodology for assigning the designation is as follows:

  • Option #1 – Retain the current ozone nonattainment designations, includes Maricopa County: applicable if both Queen Valley and Gila ambient monitoring stations demonstrate compliance with the 2015 ozone NAAQS.
  • Option #2 – Expand the current ozone nonattainment designations, would include Maricopa County and Pinal County: applicable if the Queen Valley ambient monitoring station is not in compliance with the 2015 ozone NAAQS.
  • Option #3 – Expand the current ozone nonattainment designations, would include Maricopa County and Gila County: applicable if the Gila ambient monitoring station is not in compliance with the 2015 ozone NAAQS.
  • Option #4 – Expand the current ozone nonattainment designations, would include Maricopa County, Pinal County, and Gila County: applicable if both Queen Valley and Gila ambient monitoring stations are not in compliance with the 2015 ozone NAAQS.

ADEQ will be holding two additional stakeholder meetings to address the proposed ozone nonattainment designations, scheduled in June and August of this year.  ADEQ's final proposal to US EPA regarding ozone nonattainment designations will be delivered on October 15, 2015.  US EPA will provide final nonattainment designations for the state of Arizona in October 2017.