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Air Quality Improvement Planning

Air Quality Nonattainment Areas & Areas Redesignated to Attainment

Revised On: Apr. 8th, 2026 - 01:44 pm

The U.S. Environmental Protection Agency (EPA) sets National Ambient Air Quality Standards (NAAQS) for six criteria pollutants that can be harmful to public health and the environment. The criteria pollutants are carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ground-level ozone (O3), particulate matter (PM2.5 and PM10), and sulfur dioxide (SO2). The Clean Air Act requires EPA to periodically review the standards and the science behind them to determine if a standard needs to be changed, creating a new standard. 

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Nonattainment Areas

Areas that have air monitoring data for criteria pollutants above the NAAQS or are contributing to a nearby area not meeting the NAAQS are classified by EPA as a nonattainment area. After an area is designated as nonattainment, the Clean Air Act requires States to develop a State Implementation Plan (SIP) for the nonattainment area to reduce emissions of direct and precursor pollutants and bring the area into attainment of the NAAQS. The SIP may include an analysis of ambient air quality monitoring data, an emissions inventory, attainment modeling, control measure analyses, emission reduction regulations, quantitative milestones to ensure reasonable further progress, transportation/general conformity, contingency measures, a strategy for possible exceptional events demonstrations, and public process documentation. ADEQ will work with permitted facilities, local government, and community stakeholders in a collaborative effort to develop the SIPs for these nonattainment areas | View Map of Nonattainment Areas >

Paul Spur/Douglas (Part of Cochise County) 

Hayden (Parts of Gila and Pinal counties) 

Miami (Parts of Gila and Pinal counties) 

Phoenix-Mesa (Parts of Gila, Maricopa, and Pinal counties)

Phoenix-Mesa (Parts of Gila, Maricopa, and Pinal counties)

Phoenix-Mesa (Parts of Maricopa and Pinal counties)

Rillito (Part of Pima County)

Hayden (Parts of Gila and Pinal counties) 

Miami (Parts of Gila and Pinal counties)

Phoenix-Mesa (Parts of Gila, Maricopa, and Pinal counties)

Phoenix-Mesa (Parts of Maricopa and Pinal counties)

West Pinal (Part of Pinal County)

West Central Pinal (Part of Pinal County)

Nogales (Part of Santa Cruz County)

Yuma (Part of Yuma County)

Redesignated Nonattainment Areas 

When air quality in the nonattainment area improves, the area can be redesignated from nonattainment to attainment, but this process doesn’t happen automatically. In order for an area to be redesignated, the following conditions must be met:

  • The air quality monitoring data must show that the area has met the NAAQS, 
  • The air quality improvements must be a result of permanent and enforceable control measures, 
  • All nonattainment requirements applicable to the area with respect to Section 110 and Part D of the Clean Air Act must be met, and
  • The State must submit a Maintenance Plan and Redesignation Request to EPA that meets the requirements for maintenance plans under Section 175A of the Clean Air Act including a demonstration that the area will maintain the NAAQS beyond redesignation and ensure sufficient contingency measures to promptly correct any violation of the NAAQS that may occur. 

Former nonattainment areas that have officially been redesignated to attainment status by EPA are referred to as maintenance areas for the first 20 years following redesignation | View Map of Redesignated Nonattainment Areas >

Douglas (Part of Cochise County)

Miami (Part of Gila County)

Payson (Part of Gila County)

Morenci (Part of Greenlee County)

Phoenix-Mesa (Part of Maricopa County)

Phoenix-Mesa (Parts of Maricopa and Pinal Counties) 

Bullhead City (Part of Mohave County)

Ajo (Part of Pima County)

Tucson (Part of Pima County)

Phoenix-Mesa (Parts of Maricopa and Pinal Counties) 

San Manuel (Part of Pinal County) 

Nogales (Part of Santa Cruz County)

Yuma (Part of Yuma County) 

Counties with no current nonattainment or redesignated nonattainment areas include:

  • Apache County
  • Coconino County
  • Graham County
  • La Paz County
  • Navajo County
  • Yavapai County

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National Ambient Air Quality Standards

EPA Nonattainment Areas for Criteria Pollutants | Learn More >

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