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R. Charon Gwynn,¹ Richard T. Burnett,² and George D. Thurston¹

¹Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York, USA
²Health Canada, Ottawa, Ontario, Canada

Abstract

A component of particulate matter (PM) air pollution that may provide one biologically plausible pathway for the observed PM air pollution-health effect associations is aerosol acidity (H⁺) . An increasing number of observational studies have demonstrated associations between H⁺ and increased adverse health effects in the United States and abroad. Although studies have shown significant H⁺ associations with increased morbidity in the United States, similar associations have yet to be shown with daily mortality. We considered a 2.5-year record of daily H⁺ and sulfate measurements (May 1988-October 1990) collected in the Buffalo, New York, region in a time-series analysis of respiratory, circulatory, and total daily mortality and hospital admissions. Other copollutants considered included particulate matter 10 µm in aerodynamic diameter, coefficient of haze, ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Various modeling techniques were applied to control for confounding of effect estimates due to seasonality, weather, and day-of-week effects. We found multiple significant pollutant-health effect associations--most strongly between SO₄^2- and respiratory hospital admissions (as indicated by its t-statistic) . Additionally, H⁺ and SO₄^2- demonstrated the most coherent associations with both respiratory hospital admissions [H⁺: relative risk (RR) = 1.31 ; 95% confidence interval (CI) , 1.14-1.51 ; and SO₄^2-: RR = 1.18, CI, 1.09-1.28] and respiratory mortality (H⁺: RR = 1.55, CI, 1.09-2.20 ; and SO₄^2-: RR = 1.24, CI, 1.01-1.52) . Thus, acidic sulfate aerosols represent a component of PM air pollution that may contribute to the previously noted adverse effects of PM mass on human health, and the associations demonstrated in this study support the need for further investigations into the potential health effects of acidic aerosols. Key words: acid aerosols, air pollution, epidemiology, mortality, hospital admissions, particulate matter, time-series techniques. Environ Health Perspect 108:125-133 (2000) . [Online 30 December 1999]

http://ehpnet1.niehs.nih.gov/docs/2000/108p125-133gwynn/ abstract.html

Address correspondence to R.C. Gwynn, New York University School of Medicine, Nelson Institute of Environmental Medicine, 57 Old Forge Road, Tuxedo, NY 10987-5007 USA. Telephone: (914) 731-3564. Fax: (914) 351-5472. E-mail: chgwynn@banet.net

This research was conducted as part of the fulfillment of Ph.D. requirements at New York University.

Funding for this study was provided by Health Canada, the National Institute of Environmental Health Sciences under grants ES04612 and ES05711, and the U.S. Environmental Protection Agency under STAR grant R825264-010.

Received 26 October 1998 ; accepted 23 August 1999.