Smoking determinants and exhaled CO as an indicator of smoking intensity among Indonesian students: evidence from a school-based prevention program

Smoking among Indonesian youth remains a major public health concern. While behavioral predictors of smoking are well documented, empirical evidence on the effectiveness of biomarkers, such as exhaled carbon monoxide (eCO) levels in predicting smoking intensity is limited. This study examined factors correlated with smoking behavior and investigated the relationship between eCO levels, smoking intensity, and quit intentions. This study used secondary data from the Indonesian Ministry of Health’s School-Based Smoking Prevention Program, involving 9,856 students aged 8–21 years across four provinces (2023–2024). Variables included smoking status, demographics, knowledge, and social exposure, with eCO levels measured using a smoker analyzer. Multinomial logistic regression identified predictors of smoking, while group comparisons and correlation analyses examined differences in eCO levels across smoking status groups and their correlations with smoking intensity. Logistic regression further assessed the correlation between eCO levels and quit intentions. Of the 9,856 students, 63.6% were non-smokers, 18.1% were ever smokers, and 18.3% were current smokers. Smoking prevalence was substantially higher among boys (34.2%) than girls (1.5%, p < 0.001). Multinomial logistic regression showed that being male, older age, and having close friends who smoke were significant predictors of current smoking. eCO levels were significantly higher in current smokers compared to ever smokers and non-smokers (p < 0.001) and were moderately correlated with daily cigarette consumption (ρ = 0.494, p < 0.001). Logistic regression further indicated that higher eCO levels were correlated with lower intentions to quit smoking (OR = 1.108, 95% CI: 1.072–1.145, p < 0.001). Smoking among Indonesian students is strongly influenced by age, sex, and peer smoking. Higher eCO levels reflect smoking intensity, and are linked to lower quit intentions, indicate the level of smoking intensity and dependence-smoking behaviors. The study underscores the need for targeted prevention and cessation strategies in schools.