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Ajo | PM-10 Nonattainment Area

County Affected:

Parts of Pima County | View on a Map >

Nonattainment Area Designation Date:

Oct. 31, 1990
(55 FR 45799)

Classification Level: 


Pollutant of Concern:

PM10 (particulate matter 10 microns or less in diameter; 1987 standards)


The concentration of PM10 in the air in Ajo has been below federal standards for several years. ADEQ is developing a redesignation request so that EPA will reclassify the area as an attainment area. As part of this request, ADEQ will provide an updated emissions inventory, modeling demonstration, strategy for Exceptional Events and rules for PM10 controls.

Sources of Pollutant:

  • Inactive Ajo smelter tailings pile
  • Inactive slag reprocessing facility
  • Unpaved roads
  • Cleared/vacant lot areas

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