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In Hong Kong, chronic obstructive pulmonary disease (COPD) was the 5th leading cause of death, and accounted for at least 4% of all public hospital acute admissions in 2003. The prevalence of COPD among elderly Chinese (age ≥70 years) living in Hong Kong is estimated to be 9%. Previous studies have shown that pulmonary function and quality of life among patients with COPD were adversely affected by frequent exacerbations.

A study was carried out by the Department of Medicine and Therapeutics and the Department of Community and Family Medicine of the Chinese University of Hong Kong and has just been published in the journal THORAX. This study assessed the relationship between the levels of ambient air pollutants and the hospitalization rate due to COPD in Hong Kong.

Data of daily emergency hospital admissions to 15 major hospitals in Hong Kong for COPD and indices of air pollutants (sulphur dioxide [SO2], nitrogen dioxides [NO2], ozone [O3], particulates with an aerodynamic diameter of less than 10mm [PM10] and 2.5mm [PM2.5]) and meteorological variables from January 2000 to December 2004 were obtained from several government departments.

Significant associations were found between hospital admissions for COPD with all 5 air pollutants. For every 10mg/m3 increase in SO2, NO2, O3, PM10 and PM2.5, there was 0.7%, 2.6%, 3.4%, 2.4% and 3.1% increases in the rates of COPD hospitalizations respectively. O3 had the strongest effect on COPD hospitalizations. The effect of SO2, NO2, and O3 had a stronger effect on COPD admissions in the cold season (December to March) than during the warm season.

Adverse effects of ambient concentrations of air pollutants on hospitalization rates for COPD are evident, especially during the winter season in Hong Kong. Measures to improve air quality are urgently needed.