Temporal relationship between air pollutants and hospital admissions for chronic obstructive pulmonary disease in Hong Kong.
OBJECTIVE
To assess any relationship between the levels of ambient air pollutants and hospital admissions for chronic obstructive pulmonary disease (COPD) in Hong Kong.


METHODS
A retrospective ecological study was undertaken. Data of daily emergency hospital admissions to 15 major hospitals in Hong Kong for COPD and indices of air pollutants (sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), ozone (O(3)), particulates with an aerodynamic diameter of <10 microm (PM(10)) and 2.5 microm (PM(2.5))) and meteorological variables from January 2000 to December 2004 were obtained from several government departments. Analysis was performed using generalised additive models with Poisson distribution, adjusted for the effects of time trend, season, other cyclical factors, temperature and humidity. Autocorrelation and overdispersion were corrected.


RESULTS
Significant associations were found between hospital admissions for COPD with all five air pollutants. Relative risks for admission for every 10 microg/m(3) increase in SO(2), NO(2), O(3), PM(10) and PM(2.5) were 1.007, 1.026, 1.034, 1.024 and 1.031, respectively, at a lag day ranging from lag 0 to cumulative lag 0-5. In a multipollutant model, O(3), SO(2) and PM(2.5) were significantly associated with increased admissions for COPD. SO(2), NO(2) and O(3) had a greater effect on COPD admissions in the cold season (December to March) than during the warm season.


CONCLUSIONS
Ambient concentrations of air pollutants have an adverse effect on hospital admissions for COPD in Hong Kong, especially during the winter season. This might be due to indoor exposure to outdoor pollution through open windows as central heating is not required in the mild winter. Measures to improve air quality are urgently needed.
Ko
Fanny W S
FW
Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, 30-32 Ngan Shing Street, Shatin, New Territories, Hong Kong.
Tam
Wilson
W
Wong
Tze Wai
TW
Chan
Doris P S
DP
Tung
Alvin H
AH
Lai
Christopher K W
CK
Hui
David S C
DS
D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis; D000397:Air Pollution / Q000009:adverse effects* / Q000706:statistics & numerical data; D006723:Hong Kong / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D009569:Nitric Oxide / Q000009:adverse effects / Q000032:analysis; D010126:Ozone / Q000009:adverse effects / Q000032:analysis; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D012189:Retrospective Studies; D012621:Seasons; D013458:Sulfur Dioxide / Q000009:adverse effects / Q000032:analysis
D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D009569:Nitric Oxide; D010126:Ozone