Youth Indoor and Outdoor Exposure to Secondhand Smoke and Secondhand Aerosol.

Introduction: Secondhand smoke and secondhand aerosol exposure are important public health concerns. This is the first study to present separate estimates of public indoor and outdoor secondhand smoke and secondhand aerosol exposure among U.S. youth.

Methods: Data came from the 2020 National Youth Tobacco Survey, an annual cross-sectional survey of U.S. students in Grades 6-12. Self-reported past 30-day indoor and outdoor secondhand smoke and secondhand aerosol exposures were assessed separately. Weighted prevalence and adjusted prevalence ratios for each outcome were assessed among students overall and stratified by sex, school level, race/ethnicity, sexual orientation, and current tobacco product use; prevalence also was calculated among those who did not currently use tobacco.

Results: Exposure to secondhand smoke and secondhand aerosol was reported by 60.6% (95% CI=58.7, 62.4) and 44.5% (95% CI=42.1, 46.9) of U.S. youth, respectively. Among all students, 37.6% (95% CI=36.0, 39.2) and 53.3% (95% CI=51.4, 55.2) reported indoor and outdoor secondhand smoke exposure, respectively; 34.9% (95% CI=32.9, 37.4) and 36.8% (95% CI=34.6, 38.9) reported indoor and outdoor secondhand aerosol exposure, respectively. After adjustment, female versus male students (adjusted prevalence ratio=1.15-1.30) and those who currently use versus do not use combustible tobacco products (adjusted prevalence ratio=1.15-1.36) were more likely to report exposure to all outcomes.

Conclusions: Approximately 1 in 2 students overall reported outdoor secondhand smoke exposure, and 1 in 3 students reported exposures to each indoor secondhand smoke, indoor secondhand aerosol, and outdoor secondhand aerosol. Separate estimates of indoor and outdoor secondhand smoke and secondhand aerosol exposure, along with data on correlates of exposure, provide information to support comprehensive indoor and outdoor smoke-free policies.