Airborne Particles Are a Risk Factor for Hospital Admissions for Heart
and Lung Disease Antonella Zanobetti, Joel Schwartz, and Douglas W. Dockery Environmental Epidemiology Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA Abstract We examined the association between particulate matter 10 µm ; (PM10) and hospital admission for heart and lung disease in ten U.S. cities. Our three goals were to determine whether there was an association, to estimate how the association was distributed across various lags between exposure and response, and to examine socioeconomic factors and copollutants as effect modifiers and confounders. We fit a Poisson regression model in each city to allow for city-specific differences and then combined the city-specific results. We examined potential confounding by a meta-regression of the city-specific results. Using a model that considered simultaneously the effects of PM10 up to lags of 5 days, we found a 2.5% [95% confidence interval (CI) , 1.8-3.3] increase in chronic obstructive pulmonary disease, a 1.95% (CI, 1.5-2.4) increase in pneumonia, and a 1.27% increase (CI, 1-1.5) in CVD for a 10 µg/m3 increase in PM10. We found similar effect estimates using the mean of PM10 on the same and previous day, but lower estimates using only PM10 for a single day. When using only days with PM10 < 50 mg/m3, the effect size increased by 20% for all three outcomes. These effects are not modified by poverty rates or minority status. The results were stable when controlling for confounding by sulfur dioxide, ozone, and carbon monoxide. These results are consistent with previous epidemiology and recent mechanistic studies in animals and humans. Key words: air pollution, distributed lag, hierarchical model, hospital admissions, meta-analysis, meta-regression. Environ Health Perspect 108:1071-1077 (2000) . [Online 23 October 2000] http://ehpnet1.niehs.nih.gov/docs/2000/108p1071-1077zanobetti/ abstract.html Address correspondence to A. Zanobetti, Environmental Epidemiology Program, Department of Environmental Health, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115 USA. Telephone: (617) 432-4642. Fax: (617) 277-2382. E-mail: azanob@sparc6a.harvard.edu This work was supported in part by Health Effects Institute contract 70972 and National Institute of Environmental Health Sciences grant ES-07937. Received 9 February 2000 ; accepted 3 July 2000. The full version of this article is available for free in HTML or PDF formats. |