Aim and objective:
Injunctive norms about smoking, the perceived approval or acceptability of smoking from friends or wider peer group, have rarely been studied outside the Western world. We investigated injunctive norms and the associations with smoking susceptibility in adolescents in Hong Kong, where most adolescents are negative towards smoking.

Methods:
In 2017/18, 7031 Secondary 1-5 (US grade 7-11) students (48.9% boys; mean age 14.3, SD 1.7) were surveyed. Students reported the perceived approval of smoking from good friends (disapprove/neutral/approve) and the perception of whether most secondary school students accepted smoking (no/yes). Smoking susceptibility referred to the lack of a firm intention not to smoke in the next 12 months, when good friends smoked in front, or when a good friend offered a cigarette. Logistic regression yielded adjusted odds ratios (AORs) of smoking susceptibility for injunctive norms in never smokers, adjusting for socio-demographic characteristics and school clustering effect.

Results:
Overall, 1.3%, 21.1% and 77.5% of students perceived approval, neutral response and disapproval of smoking from good friends, respectively. Some (5.8%) perceived that most students accepted smoking. In never smokers (n=6472, 92.5%), compared with perceived disapproval from good friends, perceived neutral response (AOR 3.58, 95% CI 2.86-4.50) and approval (5.41, 2.93-9.97) were associated with smoking susceptibility. The perception that most students accepted smoking was also associated with smoking susceptibility (2.73, 2.02-3.71).

Conclusions:
Injunctive norms were associated with smoking susceptibility in Hong Kong never smoking adolescents. Addressing misperceptions of others’ approval or acceptability of smoking may help prevent adolescent smoking.

Funding:
General Research Fund (17629016), Research Grants Council of Hong Kong Special Administrative Region, China.