Restructuring areas, reshaping norms: Denormalizing (e-)cigarette use in Swiss vocational and high schools

INTRODUCTION Adolescents often overestimate peer smoking and vaping, increasing the likelihood of initiation.School environments play a central role in shaping these perceptions.This study therefore aimed to examine whether a schoolbased environmental intervention modifying the school environment can shift adolescents' perceived norms and reduce (e-)cigarette use.METHODS A quasi-experimental pre-post study was conducted in three Swiss secondary schools (March-June 2024; baseline n=664; follow-up n=884).The intervention comprised a multi-component environmental approach, including the relocation of designated smoking areas to less visible locations, accompanying signage, improvements to non-smoking areas, and informational posters.Perceived peer (e-)cigarette use, and self-reported (e-)cigarette use were reported through online surveys at baseline and at one month post-intervention.RESULTS Effects varied across schools.In School 1, perceived prevalence of (e-) cigarette use decreased (cigarettes: β= -0.44; 95% CI: -0.68 --0.21; e-cigarettes: β= -0.53; 95% CI: -0.80 --0.25).In School 2, reductions differed by (e-)cigarette use: never and former users reported lower perceived cigarette prevalence at follow-up, whereas occasional and regular users showed no change.Perceived e-cigarette prevalence decreased (β= -0.42; 95% CI: -0.69 --0.15).In School 3, changes varied by (e-)cigarette use, with regular users reporting lower perceived cigarette prevalence (interaction: β= -1.60; 95% CI: -2.75 --0.45).Perceived e-cigarette prevalence did not change.Across schools, the intervention did not affect (e-)cigarette use.CONCLUSIONS A school-based environmental intervention modifying the school environment may influence adolescents' descriptive norms, although effects appear to depend on baseline policies and implementation context.