Household Exposure to Secondhand and Thirdhand Smoke and Associated Factors Among Preschool-Aged Children - Beijing Municipality, China, 2023.

What is already known about this topic?: Limited evidence exists on the prevalence and determinants of concurrent secondhand smoke (SHS) and thirdhand smoke (THS) exposure in Chinese households, particularly in Beijing, where highly urbanized districts and urban-rural transition zones coexist. What is added by this report?: Among the 1,839 surveyed households, 41.3% of preschool-aged children (3-6 years) were exposed to THS, with 21.6% experiencing combined SHS-THS exposure and 19.7% exposed to THS alone. Lower parental awareness of tobacco hazards significantly increased the likelihood of combined exposure. While partial indoor smoking bans were associated with a reduced likelihood of SHS exposure, only comprehensive indoor smoking bans effectively mitigated THS exposure. Children living in completely smoke-free homes were 3.3 times more likely to be entirely free from tobacco smoke exposure than those living in homes lacking any restrictions. What are the implications for public health practice?: Tobacco control initiatives targeting families of preschoolers should include THS prevention and emphasize the limitations of partial indoor smoking bans. Public health initiatives should prioritize full smoke-free homes to eliminate children's household tobacco exposure. Targeted, culturally tailored interventions are required for high-risk groups like multigenerational households to translate hazard awareness into consistent protective behaviors.