| Mortality Effects of a Copper Smelter Strike and Reduced Ambient Sulfate Particulate Matter Air Pollution C. Arden Pope III, Douglas L. Rodermund, and Matthew M. Gee Department of Economics, Brigham Young University, Provo, Utah, USA Abstract
Background: Numerous studies have reported associations between fine particulate and sulfur oxide air pollution and human mortality. Yet there continues to be concern that public policy efforts to improve air quality may not produce actual improvement in human health. Objectives: This study retrospectively explored a natural experiment associated with a copper smelter strike from 15 July 1967 through the beginning of April 1968. Methods: In the 1960s, copper smelters accounted for approximately 90% of all sulfate emissions in the four Southwest states of New Mexico, Arizona, Utah, and Nevada. Over the 8.5-month strike period, a regional improvement in visibility accompanied an approximately 60% decrease in concentrations of suspended sulfate particles. We collected monthly mortality counts for 1960–1975 and analyzed them using Poisson regression models. Results: The strike-related estimated percent decrease in mortality was 2.5% (95% confidence interval, 1.1–4.0%) , based on a Poisson regression model that controlled for time trends, mortality counts in bordering states, and nationwide mortality counts for influenza/pneumonia, cardiovascular, and other respiratory deaths. Conclusions: These results contribute to the growing body of evidence that ambient sulfate particulate matter and related air pollutants are adversely associated with human health and that the reduction in this pollution can result in reduced mortality. Key words: air pollution, copper smelter, mortality, natural experiment, particulate matter, sulfates. Environ Health Perspect 115:679–683 (2007) . doi:10.1289/ehp.9762 available via http://dx.doi.org/ [Online 4 January 2007]
Address correspondence to C.A. Pope III, 142 FOB, Brigham Young University, Provo, UT 84602-2363 USA. Telephone: (801) 422-2157. Fax: (801) 422-0194. E-mail: cap3@byu.edu We thank W. Wilson and D. Dockery for directing us to the Trijonis visibility paper and for helping motivate this research project. This research was supported in part by funds from the Mary Lou Fulton Professorship, Brigham Young University, Provo, Utah. The authors declare they have no competing financial interests. Received 26 September 2006 ; accepted 4 January 2007.
Correction The concentration of sulfate particles noted in the manuscript originally published online as 1–1.5 µg/m3 has been corrected to ~ 2.5 µg/m3 in the introduction and the "Discussion." Also in the "Discussion," the decline in overall mortality originally was 0.2–0.7% and the estimated percent changes in mortality were 0.6–0.9% and 1.7–2.6%. They have been corrected here to 0.8–1.1%, 1.5%, and 4.0%, respectively.
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