UCSF

Background: Thirdhand smoke (THS) contains toxic residues, including carcinogens, which persist on surfaces and clothes even after cigarette smoke dissipates. The public awareness of THS and its health effects remain low. Objective: This study examined beliefs about THS among Chinese-speaking former smokers and their non-smoking family members, before and after participating in a family-based THS education program. Methods: We implemented a 2-week THS education intervention delivered by lay health workers with 30 Chinese American dyads (N=60) residing in Northern California, consisting of former smokers who quit within the past 2 years and their family members. THS beliefs were assessed using the Beliefs About Thirdhand Smoke (BATHS) questionnaire administered at pre- and postintervention. Focus groups with 8 former smokers and 7 family participants were conducted. We used multivariable regression with Generalized Estimating Equations to account for time points and household correlations to assess changes in BATHS scores (Overall, Persistence and Health subscales). Focus group transcripts underwent independent coding by two researchers and thematic analysis. Results: The study sample included 30 male former smokers (37% with slight to mild craving for smoking), and 30 family members (97% female) who never smoked. A majority (82%) spoke English less than well, 83% were married, 58% lived with children and 27% with current smokers. All multivariable models showed a significant time x role (former smokers vs family) interaction (p < 0.05). Former smokers had lower BATHS scores than their family at preintervention (p < 0.01), but their scores became similar at post-intervention. Former smokers’ BATHS scores increased from pre- to post-intervention (Overall: p=0.02; Persistence: p=0.03; Health: p=0.04) while family had no significant change. Prominent themes from focus groups supported gaining new knowledge for both persistence and health effects of THS. Both former smokers and family members appreciated learning about cleaning methods and both shared increased family discussions and collaboration in household cleaning post intervention. Conclusion: THS education impacts former smokers and their non-smoking family members differently. Family-based interventions are promising to align beliefs and promote collaboration within households in addressing THS. Future randomized controlled trials should investigate broader impacts of the program on enhancing support for motivating quitting for current smokers, maintaining smoking abstinence, and in reducing THS exposure.