| Effect of Air Pollution on Daily Mortality in Hong Kong Chit-Ming Wong, Stefan Ma, Anthony Johnson Hedley, and Tai-Hing Lam Department of Community Medicine, The University of Hong Kong, Hong Kong, China Abstract
In different weather conditions, constituents and concentrations of pollutants, personal exposure, and biologic responses to air pollution may vary. In this study we assessed the effects of four air pollutants on mortality in both cool and warm seasons in Hong Kong, a subtropical city. Daily counts of mortality, due to all nonaccidental causes, and cardiovascular and respiratory diseases were modeled with daily pollutant concentrations [24-hr means for nitrogen dioxide, sulfur dioxide, and particulate matter < 10 µm in aerodynamic diameter (PM10) ; 8-hr mean for ozone]. using Poisson regression. We controlled for confounding factors by fitting the terms in models, in line with those recommended by the APHEA (Air Pollution and Health: a European Approach) protocol. Exposure-response relationships in warm and cool seasons were examined using generalized additive modeling. During the cool season, for a linear extrapolation of 10th-90th percentiles in the pollutant concentrations of all oxidant pollutants, NO2, SO2, and O3, we found significant effects on all the mortality outcomes under study, with relative risks (RR) of 1.04-1.10 (p < 0.038, except p = 0.079 for SO2 on respiratory mortality) . We observed consistent positive exposure-response relationships during the cool season but not during the warm season. The effects of PM10 were marginally significant (RR = 1.06 ; p = 0.054) for respiratory mortality but not for the other outcomes (p > 0.135) . In this subtropical city, local air quality objectives should take into account that air pollution has stronger health effects during the cool rather than warm season and that oxidant pollutants are more important indicators of health effects than particulates. Key words: air pollutant concentrations, daily mortality, exposure-response, offset, stratification by seasons. Environ Health Perspect 109:335-340 (2001) . [Online 8 March 2001] http://ehpnet1.niehs.nih.gov/docs/2001/109p335-340wong/ abstract.html Address correspondence to A.J. Hedley, Department of Community Medicine, The University of Hong Kong, Patrick Manson Building South Wing, 7 Sassoon Road, Hong Kong, China. Telephone: (852) 2819 9282 / 2819 9280. Fax: (852) 2855 9528. E-mail: hrmrajh@hkucc.hku.hk We thank R. Atkinson and R. Anderson for their advice on data analysis ; M. Chi for secretarial support, and P. Chau for data analysis support. Received 12 May 2000 ; accepted 24 October 2000.
The full version of this article is available for free in HTML or PDF formats. |
