Status of home-based secondhand smoke exposure among children and its association with health risks in Japan

Objectives: In Japan, secondhand smoke (SHS) exposure in children has changed with increased heated tobacco products (HTPs) and electronic cigarettes (e-cigs) use. We clarified the status of home-based SHS exposure among children, including HTPs and e-cigs, as well as maternal perceptions on SHS avoidance and examined its association with health risks. Methods: This cross-sectional questionnaire-survey-based study included 379 mothers who were raising children aged < 5 years. Results: We found that 31.1 % of the children had home-based SHS exposure, with widespread HTP and e-cig use among smoking mothers and family members (74.2 % and 67.0 %, respectively). Significantly (p < 0.05), HTP and cigarettes were used in the kitchen and gardens/balconies, and maternal perceptions of child SHS-exposure avoidance were lower among smokers than non-smokers. Non-smoking mothers also had low perceptions of smoking on balconies and having immediate post-smoking contact with their children (27.6 % and 27.9 %, respectively). Most non-smoking mothers (76.4 %) reported that they do not encourage family members to quit smoking. The structural equation model showed that the presence of smoking at home and low maternal perceptions was correlated with SHS-related child health risks, including respiratory diseases, otitis media, and dental caries. Conclusions: HTP and e-cig use in the household has been rapidly increasing even among mothers and family members, and the presence of smokers at home and low maternal perceptions may be associated with child health risks. Increasing the maternal awareness of the child health risks of home-based SHS, including HTPs and e-cigs, along with continued smoking-cessation support involving mothers and families, is indispensable.