County Affected:

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

Nonattainment Area Designation Date:

Aug. 5, 2013
(78 FR 47191)

Pollutant of Concern:

Sulfur Dioxide (2010 standard)

Summary: 

 The concentration of SO₂ in the air in Hayden has been above federal standards for several years. ADEQ submitted a nonattainment State Implementation Plan (SIP) to EPA in March 2017. In 2018, ASARCO completed numerous improvements to the Hayden smelter as part of a $180 million converter retrofit project that has substantially reduced SO₂ emissions. Some of the controls implemented at the copper smelter include:

• Ventilation hooding over furnaces
• Wet gas cleaning system improvements
• High surface area lime injection system for secondary hood baghouse and furnace ventilation baghouse
• Stringent SO₂ emission limits established to meet federal standards

On May 21, 2020 the EPA proposed to partially approve and partially disapprove Arizona’s SIP revision for attaining the 2010 1-hour primary SO₂ national ambient air quality standard for the Hayden SO₂ nonattainment area. ADEQ is currently working on a supplemental submittal to address deficiencies identified by EPA.

Source of Pollutant:

• Copper smelter

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