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Phoenix | Ozone Nonattainment Area

County Affected:

Parts of Maricopa, Gila and Pinal County | View on a Map >

Nonattainment Area Designation Date:

2008 National Ambient Air Quality Standard
May 4, 2016

2015 National Ambient Air Quality Standard
June 4, 2018

Classification Level: 

Moderate, classification under the 2008 ozone standard. Marginal classification under the 2015 ozone standard.

Pollutant of Concern:

  • Ozone (2008 standard; 75 ppb)
  • Ozone (2015 standard; 70 ppb)


The concentration of ozone in the air in Phoenix is above the 2008 and 2015 ozone standard. Maricopa Association of Governments (MAG) submitted a plan to EPA in January 2017 for the 2008 ozone standard.

Key controls in the plan include:

  • Summer fuel reformulation
  • Emissions testing
  • Federal Tier 2 and Tier 3 vehicle fuel standards
  • Coordinated traffic signal systems

MAG submitted a plan to EPA on July 8, 2020 for the 2015 ozone standard.

Sources of Pollutant: 

  • Industrial solvents and coating use 
  • Residential/industrial fuel combustion
  • Open burning/wildfires
  • Cars and trucks

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