Home and Vehicle Secondhand smoke exposure among US youth: Prevalence, correlates, and effect on academic performance

Introduction Private settings are major sources of secondhand smoke (SHS) exposure among youth. We measured youth exposures to home and vehicle SHS, and investigated effect of exposure on academic performance. Methods The 2016 National Youth Tobacco Survey of US 6th-12th graders was analyzed (n=20,675). Exposure was a report of having breathed SHS in a vehicle and in the home within the past 7 days. Primary outcome was grade repetition, measured with a surrogate indicator ‘Later-Age-Than-Expected for grade’ (LATE)—defined as being older than peers in the same grade based on age-grade placement standards. Being over-aged relative to peers within the same grade level could be indicative of either delayed school entry, or having repeated the same or earlier grade levels ≥1 time—both of which are associated with poor academic performance. Descriptive and multivariable analyses were performed among all students and never tobacco users. Results Among all students, past-7-day SHS exposures were: vehicle (21.4%, 5.56 million); home (21.7%, 5.64 million); vehicle or home (29.0%, 7.50 million); vehicle and home (14.0%, 3.63 million). Prevalence of past 7-day home or vehicle SHS exposure was: tobacco-free households, 6.5%; households with combustible-only users, 42.9%; households with smokeless tobacco/e-cigarette-only users, 15.3%; and households with combined tobacco products usage, 60.1%. Among never tobacco product users, odds of LATE were higher among those exposed to SHS in car/home non-daily (AOR=1.62; 95%CI=1.13-2.31) and daily (AOR=1.95; 95%CI=1.22-3.13) than unexposed. Conclusions Academic performance was associated with SHS exposure. Smoke-free environments, including homes/cars, are critical to protect youth from SHS exposure