Background Many epidemiological studies have shown positive association bet
ween respiratory health and current levels of outdoor air pollution in Euro
pe and America.
Objective The aim of this study was to investigate the association between
air pollution and the number of childhood admissions for asthma in Hong Kon
Methods Daily counts of childhood admission for asthma to a large teaching
Hospital were obtained from the computerized database for the period 1993-1
994. A Poisson regression allowing for seasonal patterns and meteorological
conditions was used to assess the associations between the number of Hospi
tal admissions and the three pollutants: nitrogen dioxide, sulphur dioxide
and inhalable particles (measured as PM10, particles < 10 mum in aerodynami
Results A total of 1217 children under 15 years of age were admitted for as
thma during the study period. The calculated annual hospitalization rates w
ere 283 and 178 per 100 000 for boys and girls, respectively. The mean PM10
, NO2 and SO2 levels were 44.1 mug/m(3), 43.3 mug/m(3), and 12.2 mug/m(3),
respectively. Daily admission for asthma increased significantly with incre
asing ambient level of nitrogen dioxide (relative risk (RR) = 1.08 per 10 m
ug/m(3) increase), sulphur dioxide (RR = 1.06) and inhalable particles (RR
= 1.03). No association was found between hospital admission and humidity,
temperature or atmospheric pressure.
Conclusion This is the first daily time series study of childhood admission
s for asthma and air pollution in Hong Kong. The results support that curre
nt levels of air pollution contribute to the respiratory morbidity in asthm
atic children in Hong Kong.