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Asthma is a common airway disease in HK. Recent studies by The Chinese University of Hong Kong have shown that the prevalence rate of asthma in children aged 6-7 and 13-14 years was 9.4%, while the prevalence rate in the elderly population (aged ≥70 years) was 5.8% in Hong Kong.

A study was conducted by the Department of Medicine and Therapeutics and the Department of Community and Family Medicine of The Chinese University of Hong Kong in 2006 to assess the the relationship between the levels of ambient air pollutants and the hospitalization rate due to asthma in Hong Kong. The results have just been published in the journal Clinical and Experimental Allergy.

Significant associations were found between hospital admissions for asthma to 15 major hospitals in Hong Kong and the levels of NO2, O3, PM10 and PM2.5 from January 2000 to December 2005. For every 10mg/m3 increase in NO2, O3, PM10 and PM2.5, there were 2.8%, 3.4%, 1.9% and 2.1% increases in the rates of asthma hospitalizations respectively. The younger age group (0-14 years) tended to have a higher risk for each 10g/m3 increase in pollutants than those aged 15-65 years. The elderly (aged ≥65 years) had a shorter lag time to develop asthma exacerbation following exposure to pollutants than those aged <65 years.

O3 was the most important air pollutant associated with increased hospitalizations for asthma. The harmful effects of air pollutants appeared more pronounced in the young and the elderly when compared to the rest of the adult population. Adverse effects of ambient concentrations of air pollutants on hospitalization rates for asthma are evident. Measures to improve air quality in Hong Kong are urgently needed.