SummaryObjective To examine the association of air pollutants with hospital admission for childhoodasthma in Hong Kong.Methods Data on hospital admissions for asthma, influenza and total hospital admissions inchildren aged418 years at all Hospital Authority hospitals during 1997–2002 were obtained.Data on daily mean concentrations of particles with aerodynamic diameter o10 mm (i. e.PM10) and o2.5 mm (i. e. PM2.5), nitrogen dioxide (NO2), sulphur dioxide (SO2), and ozone(O3) and data on meteorological variables were associated with asthma hospital admissionsusing Poisson’s regression with generalized additive models for correction of yearly trend,temperature, humidity, day-of-week effect, holiday, influenza admissions and total hospitaladmission. The possibility of a lag effect of each pollutant and the interaction of differentpollutants were also examined.Results The association between asthma admission with change of NO2, PM10, PM2.5 and O3levels remained significant after adjustment for multi-pollutants effect and confoundingvariables, with increase in asthma admission rate of 5.64% (3.21–8.14) at lag 3 for NO2, 3.67%(1.52–5.86) at lag 4 for PM10, 3.24% (0.93–5.60) at lag 4 for PM2.5 and 2.63% (0.64–4.67) atlag 2 for O3. Effect of SO2 was lost after adjustment.Conclusion Ambient levels of PM10, PM2.5, NO2 and O3 are associated with childhood asthmahospital admission in Hong Kong.Keywords air pollution, asthma, children, Hong Kong, hospital admissionSubmitted 25 November 2005; revised 21 April 2006; accepted 7 June 2006
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