Factors Associated with Cigarette, E-Cigarette, and Dual Use among South Korean Adolescents.

Dual use of e-cigarettes and cigarettes has become common among Korean adolescents but has decreased among adults. Dual use refers to using two tobacco products; however, in this study, it is defined as using both e-cigarettes and cigarettes. We assessed the prevalence of dual use among Korean adolescents and its relationship with socio-demographic, smoking-related characteristics, and other risk behaviors. The 2019 Korea Youth Risk Behavior Survey's data on 57,303 adolescents were analyzed using logistic regression. Overall, 13.8% had recently (in the past 30 days), used some type of cigarette, 3.3% were dual users, 3.4% exclusively smoked conventional cigarettes, and 0.6% exclusively vaped e-cigarettes. After adjusting for socio-demographic and psychological factors, substance use, smoking initiation by 13 years, secondhand smoke in school and public, and amount of cigarette consumption proved significant for all cigarette user types. Dual use was strongly associated with younger age (≤15 years), cigarette smoking initiation before 13 years, secondhand smoke exposure at school, and heavy cigarette smoking. Limited smoking cessation attempts, secondhand smoke exposure in public, and ease of cigarette purchases decrease the odds of adolescents becoming dual users. Thus, surveillance and enforcement of the juvenile protection measures need updating to prevent a shift into dual use.