A systematic review of secondhand tobacco smoke exposure and smoking behaviors: Smoking status, susceptibility, initiation, dependence, and cessation

• Secondhand smoke exposure is associated with being a smoker.
• Secondhand smoke exposure increases smoking susceptibility and initiation.
• Secondhand smoke exposure may increase nicotine dependence in adults.
• Secondhand smoke exposure hinders smoking cessation

ObjectivesTo examine the association between secondhand tobacco smoke exposure (SHSe) and smoking behaviors (smoking status, susceptibility, initiation, dependence, and cessation).MethodsTerms and keywords relevant to smoking behaviors and secondhand tobacco smoke exposure were used in a search of the PubMed database. Searches were limited to English language peer-reviewed studies up till December 2013. Included papers: a) had clearly defined measures of SHSe and b) had clearly defined measures of outcome variables of interest. A total of 119 studies were initially retrieved and reviewed. After further review of references from the retrieved studies, 35 studies were finally selected that met all eligibility criteria.ResultsThe reviewed studies consisted of thirty-five (89.7%) studies with differing measures of SHSe (including questionnaire and biological measures) and varying definitions of main outcome variables of interest between studies. The majority of the studies (77%) were cross-sectional in nature. The majority of studies found that SHSe was associated with greater likelihood of being a smoker, increased susceptibility and initiation of smoking, greater nicotine dependence among nonsmokers, and poorer smoking cessation.ConclusionsThe review found positive associations between SHSe and smoking status, susceptibility, initiation and nicotine dependence and a negative association with smoking cessation. In light of design limitations, future prospective and clinical studies are needed to better understand the mechanisms whereby SHSe influences smoking behaviors.