Longitudinal changes and predictors of secondhand smoke exposure at home in mothers and young children in Hong Kong

Abstract

SIGNIFICANCE: We investigated the pattern and factors associated with 3-year changes in home SHS exposure among mothers and young children in Hong Kong, the most densely populated city in China but with one of the lowest smoking prevalence in the world. METHODS: 771 non-smoking mothers and their children aged ≤18 months were recruited in 4 of the 33 Maternal and Child Health Centers (MCHCs) in 2012 and the mothers were followed after 3 years through telephone interviews. SHS exposure at home, health conditions and family smoking and related behaviours were recorded. Out of the 260 families with a smoking father and no other smokers at baseline, we included 161 families (61.9%) which were successfully followed. Logistic regression yielded adjusted odds ratios (OR) for a reduction in home SHS exposure in relation to demographics and smoking related factors. RESULTS: Home SHS exposure was non-significantly reduced from 40.1% to 37.3% or 218.3 to 163.1 minutes per week in children; and from 47.8% to 42.2% or 247.8 to 215.1 minutes per week in mothers (effect size was small to medium). Prevalence of exposure was unchanged, increased and decreased in 67.1%, 14.9% and 18.0% of children, and 67.1%, 13.7% and 19.2% of mothers, respectively. Living in subsidized home ownership housing (OR: 5.66, 95% CI 1.51-21.22) (vs public rental housing), and maternal SHS avoidance behaviours (OR per 1 more behavior: 1.61, 95% CI 1.17-2.23) predicted a reduction in children’s SHS exposure at home. Similar associations were observed in mothers’ home SHS exposure and the corresponding ORs were 3.80 (1.12-12.73) and 1.42 (1.06-1.89). CONCLUSIONS: Mothers and children in Hong Kong had slight to moderate but non-significant reduction in SHS exposure at home during 2012 to 2015. Future interventions should target public rental housing, and promote home SHS avoidance behaviours.