Passive smoking and respiratory symptoms in primary school children in Hong Kong

Abstract

1. We aimed to study whether passive smoking is associated with respiratory ill health in primary school children in Hong Kong. 2. In this cross-sectional study, a standardised structured questionnaire was used to obtain information on respiratory symptoms, smokers in the household and smoking habit of the children. A random sample of 30 primary schools was included. Four classes were randomly selected for each school, one class each from each school year of primary 3-6. A total of 3964 children aged 8-13 years completed the questionnaire during October 1995-May 1996. The response rate was over 94%. 3. In 3480 children who had never smoked, after adjusting for gender, age, place of birth and living district, the odds ratios (95% confidence interval) were: (a) throat problems, 1.35 (1.08-1.68); (b) cough, 1.54 (1.28-1.84); (c) phlegm, 1.43 (1.21-1.70); (d) wheezing, 1.21 (0.89-1.41); (e) nose problems, 1.17 (1.02-1.35). The odds ratios increased with increasing number of smokers at home (P for trend < 0.001; except for wheezing, P = 0.3). The odds ratios for having any of the above symptoms for one, two and three smokers at home were respectively 1.15 (0.99-1.34), 1.48 (1.16-1.88) and 2.03 (1.47-2.81); P for trend < 0.001. 4. We conclude that the results provide further evidence that passive smoking is a cause of respiratory ill health in school children in Hong Kong.