The association between e-cigarette use among Chinese college students and lung function and physical activity: A cross-sectional study

INTRODUCTION: Electronic cigarettes have gained widespread popularity among young adults, yet their respiratory health impacts remain incompletely understood. This cross-sectional investigation aimed to examine associations between e-cigarette use and respiratory symptoms, pulmonary function, and physical activity among Chinese university students. METHODS: This cross-sectional study was conducted at a university in China from January to August 2024. The study recruited 122 participants aged 18-30 years from a university setting, comprising 60 regular e-cigarette users with ≥1-month consistent usage and 62 tobacco-naive controls. Comprehensive assessments included respiratory symptom evaluation using the Dyspnoea-12 questionnaire, pulmonary function testing via spirometry and impulse oscillometry, fractional exhaled nitric oxide measurement, and physical activity assessment through standardized questionnaires and objective monitoring. Statistical analyses employed independent samples t-tests, Mann-Whitney U tests, and multivariable linear regression models with significance set at p<0.05. RESULTS: The investigation revealed significantly elevated respiratory symptom burden among e-cigarette users compared to controls, with Dyspnoea-12 scores reaching 2.0 versus 0 points (mean difference=2.0; 95% CI: 0.5-3.5, p=0.008, Cohen's d=0.52). Analysis suggested a potential dose-response pattern with symptom escalation from 1.0 points in short-term users (1-3 months) to 3.5 points in long-term users (7-12 months, p=0.018). Impulse oscillometry detected subtle but significant increases in peripheral airway resistance (0.31 ± 0.07 vs 0.29 ± 0.06 kPa/L.s, p=0.045) and frequency-dependent resistance changes (p=0.028), among e-cigarette users compared to controls, indicating small airway dysfunction despite preserved conventional spirometric parameters. Physical activity levels remained comparable between groups across multiple assessment domains. Multivariable regression confirmed that e-cigarette use was independently associated with elevated respiratory symptoms (β=3.12; 95% CI: 1.01-5.23, p=0.004). CONCLUSIONS: These findings demonstrate that e-cigarette use among university students is associated with clinically meaningful respiratory symptom burden and early airway dysfunction, supporting the need for further longitudinal studies and the development of symptom-based surveillance systems in academic settings.