Associations between public e-cigarette use and tobacco-related social norms among youth.

IMPORTANCE: E-cigarette use in public places may renormalise tobacco use.
OBJECTIVE: To measure associations between e-cigarette use in public places and social norms among youth.
DESIGN: Cross-sectional survey.
SETTING: School-based. PARTICIPANTS: 24 353 never tobacco users in US 6th-12th grades who completed the 2016-2017 National Youth Tobacco Surveys. EXPOSURE: Individuals were classified as exposed in public places within the past 30 days to: (1) neither e-cigarette secondhand aerosol (SHA) nor combustible tobacco secondhand smoke (SHS); (2) SHA only; (3) SHS only; and (4) both SHA and SHS. OUTCOMES: Outcomes were overestimation of peer e-cigarette use (a measure of descriptive norms), harm perception and susceptibility. Data were analysed using descriptive statistics and logistic regression (p<0.05).
RESULTS: Overall prevalence of SHS and SHA exposure in public places was 46.6% and 18.3%, respectively. SHA exposure in public places was associated with increased odds of overestimating peer e-cigarette use (adjusted OR (AOR): 1.83; 95% CI 1.29 to 2.58) and decreased odds of perceiving e-cigarettes as harmful (AOR: 0.63; 95% CI 0.51 to 0.79), compared with those exposed to neither emission. SHA exposure in public places was also associated with increased susceptibility to using e-cigarettes (AOR: 2.26; 95% CI 1.82 to 2.81) and cigarettes (AOR: 1.51; 95% CI 1.20 to 1.90). E-cigarette harm perception was lower among students in jurisdictions with no comprehensive clean indoor air laws (AOR: 0.79; 95% CI 0.71 to 0.88) or cigarette-only laws (AOR: 0.88; 95% CI 0.78 to 0.99) than in those prohibiting both cigarette and e-cigarette use in public places.
CONCLUSIONS: Prohibiting both e-cigarette and cigarette use in public places could benefit public health. © Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.