Smoking experience among Korean teens increases with age, rising from 3.93% in ninth grade to 9.59% among 16- to 17-year-old 11th graders. Photo credit: TBD Tuyên, Pexels.
A government cohort study shows that the share of Korean adolescents who have tried smoking increases sharply as students advance through school, with the steepest rise occurring between middle school and high school.
The long-term study follows 5,051 students who were in sixth grade, the final year of elementary school, when researchers launched the survey in 2019. The latest data collection took place between March and October 2025.
According to the agency’s findings released at the end of January, 9.59% of the cohort—now aged 16 to 17 and enrolled in the 11th grade—reported having smoked at least once. That figure climbed significantly from 3.93% when the same group was in ninth grade, the final year of middle school.
Smoking experimentation accelerated during the high school years, rising by nearly 3 percentage points annually. That increase nearly matched the total growth recorded across all 3 years of middle school. At the beginning of the study, when participants were still in elementary school, just 0.35% said they had tried smoking.
The survey also found that 6.13% of boys and 2.17% of girls qualified as current smokers, defined as having smoked within the previous 30 days.
Researchers identified the spread of e-cigarettes as a key factor behind the rising numbers, particularly among female students. Among girls, 1.54% reported current use of liquid-based e-cigarettes, exceeding the 1.33% who said they smoked conventional cigarettes. Overall, liquid-based e-cigarette use stood at 3.47%, while conventional cigarette use reached 2.58%, reflecting higher rates of traditional smoking among boys.
The study highlighted the influence of social surroundings on smoking behavior. Students whose friends or family members smoked, or who expressed tolerant attitudes toward smoking, showed significantly higher initiation rates and tended to start at younger ages.
In addition to smoking, the survey released interim data on alcohol use, breakfast skipping, nutrition, physical activity, and smartphone use. All indicators worsened as students grew older.
The Korea Disease Control and Prevention Agency said it will continue monitoring the cohort over the remaining 3 years of the study. About 80% of the original participants remain in the project, a retention rate the agency described as relatively high for long-term research.
“The results serve as fundamental data for building policies and improving institutions that help adolescents grow into healthy adults,” a KDCA official said. “Because adolescent habits can shape health across the entire life course, coordinated efforts by schools, families and local communities are essential.”