Introduction: To investigate the associations of parental smoking and secondhand smoke (SHS) exposure at home with smoking initiation among young children in Hong Kong.
Methods: A prospective school-based survey of Hong Kong primary 2-4 students was conducted at baseline in 2006 and followed up in 2008. Self-administered anonymous questionnaires were used to collect information about smoking, SHS exposure at home, parental smoking, and sociodemographic characteristics. Cross-sectional and prospective associations of SHS exposure at home and parental smoking with student smoking were analyzed using logistic regression adjusting for potential confounders.
Results: Cross-sectional association between parental smoking and ever smoking was significant with adjustment of sociodemographic characteristics but became insignificant after adjusting for home SHS exposure. Home SHS exposure mediated the association between parental smoking and students smoking (p = .03). Prospectively, parental smoking was not associated with smoking initiation after adjusting for home SHS exposure. Each day increase in home SHS exposure significantly predicted 16% excess risk of smoking initiation after adjusting for parental smoking. The prospective effect of parental smoking on smoking initiation was significantly mediated by baseline home SHS exposure (p < .01).
Conclusions: Higher exposure to SHS at home predicted smoking initiation of young Chinese children in Hong Kong independent of parental smoking status. On the other hand, the effect of parental smoking on smoking initiation was mediated through SHS exposure at home. To prevent children from smoking as well as the harm of SHS exposure, parents and other family members should quit smoking or at least reduce smoking at home.