Air pollution and hospital admissions for respiratory and cardiovascular diseases in Hong Kong

Abstract

Objective - To investigate short term effects of concentrations of pollutants in ambient air on hospital admissions for cardiovascular and respiratory diseases in Hong Kong. Methods - Retrospective ecological study. A Poisson regression was performed of concentrations of daily air pollutant on daily counts of emergency hospital admissions in 12 major hospitals. The effects of time trend, season, and other cyclical factors, temperature, and humidity were accounted for. Autocorrelation and over-dispersion were corrected. Daily concentrations of nitrogen dioxide (NO 2), sulphur dioxide (SO 2), ozone (O 3), and particulate matter < 10 μm in aerodynamic diameter (PM 10) were obtained from seven air monitoring stations in Hong Kong in 1994 and 1995. Relative risks (RR) of respiratory and cardiovascular disease admissions (for an increase of 10 μg/m 3 in concentration of air pollutant) were calculated. Results - Significant associations were found between hospital admissions for all respiratory diseases, all cardiovascular diseases, chronic obstructive pulmonary diseases, and heart failure and the concentration is of all four pollutants. Admissions for asthma, pneumonia, and influenza were significantly associated with NO 2, O 3, and PM 10. Relative risk (RR) for admissions for respiratory disease for the four pollutants ranged from 1.013 (for SO 2) to 1.022 (for O 3), and for admissions for cardiovascular disease, from 1.006 (for PM 10) to 1.016 (for SO 2). Those aged ≥ 65 years were at higher risk. Significant positive interactions were detected between NO 2, O 3, and PM 10, and between O 3 and winter months. Conclusions - Adverse health effects are evident at current ambient concentrations of air pollutants. Further reduction in air pollution is necessary to protect the health of the community, especially that of the high risk group.