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EPA redesignates Douglas area as attaining sulfur dioxide standard

Release Date: 12/28/2005
Contact Information: Wendy L. Chavez, (415) 947-4248


SAN FRANCISCO – The U.S. Environmental Protection Agency redesignated the Douglas, Ariz. area as having met the federal health standard for sulfur dioxide and approved the state’s plan to maintain healthy levels for the next ten years.

“We are working with the state of Arizona to make sure that federal air quality designations match the actual air quality in Arizona,” said Kerry Drake, the EPA’s Air Division associate director for the Pacific Southwest region. “The EPA, the state, and local agencies can now focus efforts on areas that are failing to meet federal air quality standards.”

The Phelps-Dodge Douglas Reduction Works smelter was the major source of SO2 in Douglas until operations closed in 1987. The smelter had the potential to emit 400,000 tons of SO2 annually, which is over 100 times the total current sources combined. There are currently several minor sources of SO2 in the Douglas area, but none produce emissions of the magnitude of the Phelps-Dodge smelter.

Why the focus on sulfur dioxide?

SO2 causes adverse health effects, including reduced lung function, increased respiratory illness, altered lung defenses, and aggravated existing cardiovascular disease. Children, the elderly, and people with asthma are the most vulnerable. SO2 has a variety of additional impacts, including acidic deposits, crops and vegetation damage, and corrosion of natural and man-made materials.

The last time the Douglas area exceeded the primary SO2 federal air quality standards occurred in 1986. There have been no monitored or modeled violations of the standards since the end of the Phelps-Dodge smelter operations.

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