摘要:INTRODUCTION :Youth exposure to secondhand smoke (SHS) and secondhand aerosol from e-cigarettes (SHA) may contribute to the renormalization of tobacco product use behaviors. Our study assessed self-reported SHS or SHA exposures in indoor or outdoor public places among US students. METHODS :Data came from the 2015 and 2017 National Youth Tobacco Survey, a school-based survey of US students in grades 6 through 12. Past 30-day exposure to SHS and SHA in indoor and outdoor public places was assessed. The prevalence of exposure was assessed overall and by covariates for each year. We used adjusted prevalence ratios (aPRs) to assess determinants of exposure. RESULTS :We observed no significant change from 2015 through 2017 in exposure to SHS (52.6% to 50.5%), SHA (25.2% to 25.6%), or either SHS or SHA (56.7% to 55.1%). Following multivariable adjustment, in 2017, exposure to either SHS or SHA in public was higher among female students versus male students (aPR = 1.29), high school students versus middle school students (aPR = 1.15), current e-cigarette users versus nonusers (aPR = 2.89), and current users of other tobacco product versus nonusers (aPR = 1.21). Exposure was higher for students who reported that a household member used tobacco products. CONCLUSION :In 2017, more than half (55.1%, 14.3 million) of US middle and high school students reported exposure to secondhand tobacco product emissions in indoor or outdoor public places. E-cigarette use may complicate the enforcement of existing smoke-free policies and contribute to the renormalization of tobacco use behaviors. Continued efforts are warranted to reduce the social acceptability of tobacco product use and protect bystanders from all tobacco product emissions.