Comprehensive smoke-free legislations prohibiting smoking in indoor areas of workplaces, bars, and restaurants have been adopted in most of the USA; however, limited efforts have focused on regulating secondhand smoke (SHS) exposure in the family car. The objective of this study was to identify the determinants and national/state-specific population support for smoke-free cars, in the presence of any occupant in general, but particularly when children are present. National data of US adults aged ≥18 years (n = 164,819) were obtained from the 2010/2011 Tobacco Use Supplement of the Current Population Survey. Among all US adults, a significantly greater proportion supported smoke-free cars when it was specified that the occupant was a child compared to when not specified (93.4 vs. 73.7 %, p < 0.05). Age, race/ethnicity, gender, current tobacco use, marital status, and the existence of household smoke-free regulations all mediated population support for smoke-free cars.
Conclusion: While differences within the US population were noted, this study however showed overwhelming support for smoke-free car policies, particularly when children are present. Policies which prohibit smoking in indoor or confined areas such as cars may benefit public health by protecting nonsmoking children and adults from involuntary SHS exposure.