The associations of asthma symptoms with active and passive smoking in Hong Kong adolescents.

BACKGROUND Tobacco smoke has detrimental effects on the respiratory system. This study investigated the associations of active and passive smoking with asthma symptoms in Hong Kong adolescents. METHODS A total of 6,494 Hong Kong secondary school students, with a mean ± SD age of 15.0 ± 1.21 years, participated in the Health Related Behavior General Survey in 2000-2001. They reported their demographic factors (sex, age, housing type, district of living), lifestyles (smoking, drinking, extracurricular sports, eating), and asthma symptoms (exercise-induced bronchospasm [EIB] and nocturnal cough) in the questionnaire. In addition, number of smoking parents (none/one/both) and presence of a smoking best friend (yes/no) were assessed. Logistic regression models were used to determine the odds ratios (OR) of frequently having the asthma symptoms for different smoking status of students, parents, and best friend, with adjustment for demographic factors and lifestyles. RESULTS The prevalence of former, light, and heavy smokers was 17.5%, 7.7%, and 1.0%, respectively. Moreover, 35.1% of the participants had one and 3.8% had 2 parents who smoked. Heavy smokers were more likely to experience EIB with OR (95% CI) of 2.27 (1.30-3.97) and nocturnal cough with OR (95% CI) of 3.45 (1.52-7.81), as well as both symptoms with OR (95% CI) = 4.69 (1.88-11.73) when compared to those who never smoked. The corresponding OR (95% CI) for having at least one smoking parent and a smoking best friend was 1.45 (1.17-1.81), 1.61 (1.06-2.42), and 2.43 (1.37-4.31), when compared with those without a parent or best friend who smoked. CONCLUSIONS Adolescents who are heavy smokers and having parents and a best friend who smoke are more likely than others to have asthma symptoms. Both active and passive smoking are related to asthma symptoms in adolescents.