Air Quality

The Sun Corridor MPO has the responsibility to ensure that the transportation projects, plans, and programs within the Sun Corridor region conform to state air quality plans for the federal air quality standards. Specifically, the Sun Corridor MPO’s Five-Year Transportation Improvement Program (TIP) and Regional Transportation Plan (RTP) must be consistent with and conform to the purpose of air quality plans for the National Ambient Air Quality Standards (NAAQS).

NAAQS have been established through the Clean Air Act for six principal pollutants, which are called “criteria” pollutants. Two areas within the Sun Corridor MPO region have been designated as nonattainment areas:

  • West Pinal PM-10 Serious Nonattainment Area – This area is in serious nonattainment status for particulate matter (dust) smaller than ten micrometers (PM-10).
  • West Central Pinal PM-2.5 Nonattainment Area – This area is in nonattainment status for particulate matter (dust) less than 2.5 micrometers in diameter.

In June 2016, the Governor certified the Maricopa Association of Governments (MAG) as the lead planning organization for the Pinal County PM-10 and PM-2.5 nonattainment areas. MAG develops air quality plans for these areas in cooperation with the Sun Corridor Metropolitan Planning Organization.

2023 Five Percent Particulate Plan for PM-10 for the West Pinal County Nonattainment Area

Pinal County implemented new West Pinal Fugitive Dust and Countywide Fugitive Dust Rules which were adopted by the Pinal County Board of Supervisors on January 25, 2023, and went into effect June 1, 2023.

Countywide Fugitive Dust

West Pinal PM10 Nonattainment Area