American Journal of Epidemiology Advance Access published online on April 15, 2008
American Journal of Epidemiology, doi:10.1093/aje/kwn078
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Practice of Epidemiology |
A Regression Approach for Estimating Multiday Adverse Health Effects of PM10 When Daily PM10 Data Are Unavailable
From the School of Finance and Applied Statistics, College of Business and Economics, Australian National University, Canberra, Australia
Correspondence to Dr. Steven Roberts, School of Finance and Applied Statistics, College of Business and Economics, Australian National University, Canberra, ACT 0200, Australia (e-mail: steven.roberts{at}anu.edu.au).
Received for publication October 4, 2007. Accepted for publication March 11, 2008.
The authors propose a regression-based approach for obtaining multiday estimates of the adverse health effects of ambient particulate matter less than 10 µm in diameter (PM10) when daily PM10 time-series data are unavailable. This situation is common in the United States, because most US cities take PM10 measurements every 6 days. Current evidence suggests that adverse effects of PM10 are not concentrated on a single day but rather are spread out over multiple days, so the unavailability of daily PM10 data presents a problem for the estimation of these effects. The proposed model estimates weights that are used to construct a linear combination of single-lag PM10 effect estimates obtained from the available PM10 data. It is shown that this new approach provides estimates of the effect of PM10 on mortality that have less bias and mean squared error than currently available methods. Application of this method to the US cities contained in the National Morbidity, Mortality, and Air Pollution Study database produces an estimated national average effect of PM10 on nonaccidental mortality in persons over age 65 years, corresponding to a 0.32% increase per 10-µg/m3 increment in PM10. The estimated effects for cardiorespiratory mortality and other mortality are 0.34% and 0.22%, respectively.
air pollution; epidemiologic methods; models, statistical; mortality; particulate matter
Abbreviations: NMMAPS, National Morbidity, Mortality and Air Pollution Study; PM10, particulate matter less than 10 µm in diameter