Smoke-Free Rules and Secondhand Smoke Exposure in Vehicles among U.S. Adults—National Adult Tobacco Survey, 2009–2010 and 2013–2014

In the United States (U.S.), secondhand smoke (SHS) exposure causes more than 41,000 deaths among nonsmoking adults annually. Adoption of smoke-free laws in public areas has increased, but private settings such as vehicles remain a source of SHS exposure. This study assessed change in voluntary smoke-free vehicle rules and SHS exposure in personal vehicles among U.S. adults between two periods, 2009-2010 and 2013-2014, using data from the National Adult Tobacco Survey (NATS). NATS is a national landline and cellular telephone survey of non-institutionalized adults aged ≥18 years in the 50 U.S. states and the District of Columbia. We assessed percentage change in the prevalence of smoke-free vehicle rules among all adults and SHS exposure in vehicles among nonsmoking adults, overall, by sociodemographic factors (sex, age, race/ethnicity, education, marital status, annual household income, U.S. region), and by cigarette smoking status. During 2009-2010 to 2013-2014, the percentage of adults with a 100% smoke-free vehicle rule increased from 73.6% to 79.5% (% change = +8.0%; p < 0.05). Among nonsmokers, SHS exposure in vehicles in the previous 7 days decreased from 9.2% to 8.2% (% change = -10.9%; p < 0.05). Smoke-free rules in private settings such as vehicles, in coordination with comprehensive smoke-free policies in indoor public settings, can help reduce SHS exposure and promote smoke-free norms.