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Smoking and E-cigarette Use in Smoke-free Schools among Secondary School Students in Thailand: A Multicenter Prospective Cohort Study

Chakkraphan Phetphum, Orawan Keeratisiroj, Vasin Pipattanachat, W. Naravage, Jutatip Kongpun, B. Promphakping, Ninlawadee Promphakping, C. Sathirapanya et al.

Asian Journal of Social Health and Behavior, 2026

Abstract

Despite legal prohibitions, electronic cigarette (E-cigarette) use among Thai adolescents is increasing. While smoke-free school policies have shown promise in reducing youth tobacco use, longitudinal evidence of their effectiveness in Thailand remains limited. This study aimed to examine the impact of smoke-free school environments on cigarette and E-cigarette use among secondary school students in four regions of Thailand.

A multicenter prospective cohort study was conducted from May 2023 to November 2024 across four points. A total of 5555 students in Grades 7 and 8 from smoke-free and nonsmoke-free schools were recruited via multistage sampling, with 1952 students completing all four data collection rounds. Data were collected via a validated self-administered online questionnaire. Descriptive statistics summarized participant characteristics and outcomes. Generalized estimating equations (GEEs) were used to assess differences in smoking-related behaviors, adjusting for potential confounders.

Students in smoke-free schools consistently reported a lower prevalence of current smoking (4.2%–4.5% vs. 4.9%–6.5%), lower smoking intention, and lower E-cigarette use intention over time. Multivariable GEE analysis revealed significantly reduced odds of smoking (adjusted odds ratio [AOR] = 0.60; 95% confidence interval [CI]: 0.43–0.86), smoking intention (AOR = 0.74; 95% CI: 0.62–0.90), and E-cigarette use intention (AOR = 0.67; 95% CI: 0.55–0.82) among students in smoke-free…

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Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence.

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