Household second-hand smoke exposure and stunted growth among Chinese school-age children

Few studies have examined the impacts of second-hand smoke exposure on children’s growth during childhood. This study aims to assess the association between heights of school-age children and their after-birth second-hand smoke exposures at home. It included 41,439 children aged 6–17 years recruited from 30 provinces in mainland China using a multi-stage stratified random sampling approach. The heights of children were measured following the standard protocol, and the household second-hand smoke exposure was investigated using a questionnaire through face-to-face interviews. Effects of secondhand smoke exposure were examined using multivariable linear and logistic regressions, adjusting for covariates and potential confounding factors. The results showed that children exposed to household second-hand smoke were lower in height than unexposed children [ β = -2.897, 95 % confidence interval (CI): -3.090, -2.703] and were at higher risk of stunting [Odds ratio (OR) =1.520, 95% CI: 1.318, 1.753]. The effects of second-hand smoke exposure did not differ by gender but were age-related and peaked in the 6–8y group (OR=3.708, 95 % CI: 2.572, 5.346). The risk of stunting increased with increasing second-hand smoke exposure duration, i.e., risk of stunting was 1.246 (CI: 1.053, 1.474), 1.904 (CI: 1.572–2.305) and 3.263 (CI: 2.203, 4.833) for the children exposed to second-hand smoke 1–10 min/d, 11–55 min/d and no less than 56 min/d, respectively, suggesting a dose–response relationship. This study indicated that household exposure to second-hand smoke impedes the growth of school-age children, and the findings warrant the need for promoting smoking-free homes. • 41439 children aged 6–17 years recruited from 30 provinces in mainland China. • Association between second-hand smoke and stunted growth was studied. • Children exposed to household second-hand smoke were lower in height. • The risk of stunting increased with longer second-hand smoke exposure duration. • First national study in China evidencing negative impact of second-hand smoke on children’s growth.