Table 2

Prevalence of outcome measures among never tobacco users, by SHA/SHS exposure status, National Youth Tobacco Survey, 2016–2017

Electronic cigaretteConventional cigarette
Overestimation of peer use*
% (95% CI)
Harm perception†
% (95% CI)
Curiosity‡
% (95% CI)
Susceptibility§
% (95% CI)
Overestimation of peer use*
% (95% CI)
Harm perception†
% (95% CI)
Curiosity‡
% (95% CI)
Susceptibility§
% (95% CI)
Overall49.8 (48.7 to 50.9)74.4 (73.7 to 75.1)11.9 (11.4 to 12.4)23.8 (23.1 to 24.5)66.7 (65.6 to 67.7)94.1 (93.8 to 94.5)13.3 (12.8 to 13.9)24.0 (23.3 to 24.6)
SHA exposure in a public place¶
Unexposed46.7 (45.4 to 47.9)75.1 (74.3 to 75.8)10.1 (9.6 to 10.7)21.2 (20.5 to 22.0)64.3 (63.1 to 65.5)94.0 (93.5 to 94.4)12.1 (11.5 to 12.7)22.4 (21.6 to 23.1)
Exposed64.2 (61.6 to 66.7)71.5 (69.8 to 73.2)20.0 (18.5 to 21.6)36.1 (34.3 to 37.9)77.6 (75.4 to 79.9)95.5 (94.7 to 96.3)19.0 (17.5 to 20.5)31.1 (29.3 to 32.9)
SHS exposure in a public place¶
Unexposed45.5 (43.9 to 47.0)75.2 (74.3 to 76.2)8.8 (8.1 to 9.4)19.6 (18.7 to 20.5)61.4 (59.9 to 62.9)93.2 (92.6 to 93.7)10.4 (9.8 to 11.1)21.5 (20.6 to 22.4)
Exposed54.6 (52.9 to 56.2)73.5 (72.4 to 74.6)15.6 (14.8 to 16.5)28.9 (27.8 to 30.0)72.5 (71.0 to 74.0)95.5 (95.0 to 96.0)16.8 (15.9 to 17.7)26.9 (25.8 to 27.9)
  • Analyses for overestimation of peer use for e-cigarettes were based on 2016 data only; all other outcomes were based on pooled 2016–2017 data. Differences statistically significant within all subgroups assessed (unexposed vs exposed) at P<0.05 using χ2 tests. SHA and SHS exposures not mutually exclusive of each other.

  • *Binary variable. Individuals reporting perceived prevalence greater than the actual prevalence in their grade within their county (absolute differences) were classified as overestimating peer use of the specified product.

  • †Perceived harm was defined as a response of ‘Some harm’, or ‘A lot of harm’ to the question, ‘How much do you think people harm themselves when they [smoke cigarettes/use e-cigarettes] some days but not every day?’.

  • ‡Curiosity was assessed with the question: ‘Have you ever been curious about [using an e-cigarette/smoking a cigarette]?’ Categorical response options were ‘definitely yes’; ‘probably yes’; ‘definitely not’; and ‘probably not’. Either of the former two responses was classified as a positive indication of being highly curious.

  • §Susceptibility was defined as lack of a firm resolve not to use the specified tobacco product soon, in the next year, or if offered by a close friend.

  • ¶Past 30-day exposure to SHS and SHA in a public place was assessed by asking, ‘During the past 30 days, on how many days did you breathe [the smoke from someone who was smoking tobacco products/the vapor from someone who was using an electronic cigarette or e-cigarette] in an indoor or outdoor public place?’ Exposure was dichotomised as ‘0’ for 0 days and ‘1’ for 1–30 days.

  • SHA, secondhand aerosol; SHS, secondhand smoke.