Agaku I, et al. - By analyzing the 2016 National Youth Tobacco Survey of U.S. 6th–12th graders (n=20,675), researchers determined the prevalence as well as correlates of home and vehicle secondhand smoke (SHS) exposure in youth. Vehicle (21.4%, 5.56 million); home (21.7%, 5.64 million); home or vehicle (29.0%, 7.50 million); vehicle and home (14.0%, 3.63 million) were reported as past-7-day SHS exposures by all students. Overall, the exposure to either home or vehicle SHS was reported by approximately one-third of U.S. youth (7.50 million). A dominant SHS exposure source was home among non-tobacco-using youth with tobacco-using household member(s), and a vehicle (possibly peers') among tobacco-using youth with non-tobacco-using household member(s). Youth SHS exposure can be attenuated via smoke-free environments, including homes and cars.