Objective: Thirdhand smoke is an important public health problem. The aim of this study is to adapt the ‘‘Beliefs About ThirdHand Smoke’’ scale developed by Haardorfer et al to Turkish, to examine its validity and reliability.

Method: This methodological study was conducted in Ankara between 01.05-29.6.2021. Turkish version of the original scale “Beliefs About ThirdHand Smoke Scale’’ was obtained firstly. For the scale validity and reliability analyzes were performed: For content validity expert views were received, for construct validity confirmatory factor analysis; for reliability internal consistency, intra-class correlation were performed. Voluntary 256 adults who applied to polyclinics of Kecioren Training and Research Hospital, spoke Turkish, communicated, smoked or living at least one person who smoked, “socyodemographic features form” and Turkish version of  the original scale “Beliefs About Third Hand Smoke Scale’’ was applied face to face. The data analysis used IBM SPSS 24.0 and AMOS 21.

Results: Turkish adaptation of the original scale “Beliefs About Third Hand Smoke Scale’’ is 9 items, 2 factors. The content validity index for all items Turkish version of  the original scale “Beliefs About Thirdhand Smoke Scale’’ is ≥0.80; there is inter-expert fit. Cronbach's alpha values overall/factors are 0.910/0.849, 0.835 respectively; scale is high reliable, factors are  acceptably reliable. Item-total correlation is 0.580-0.794; each item is acceptably distinctive, should remain at scale. Intra-class correlation, inter-items correlation matrix r values are 0.376-0.771; items are related intermediately, internally consistent. Confirmatory factor analysis goodness-of-fit values, CMIN/df=3,1, RMSEA=0,091, RMR=0,054, GFI=0,946, AGFI=0,889, NFI=0,953, CFI=0,967; two-factor structure of the scale well-fitting to the data was confirmed.

Conclusion: Turkish adaptation of the original scale developed by Haardorfer et al in 2017 “Beliefs About Thirdhand Smoke Scale’’ is a reliable and valid measurement tool.

Turkish version of  the original scale “Beliefs About Thirdhand Smoke Scale’’ can applied in studies and trainings, increase awareness of the thirdhand smoke and guide the fight against tobacco.