(บทความวจย) คาตดทเหมาะสมของคารบอนมอนอกไซดในลมหายใจออกเพอจำแนกสถานะการสบบหรในนกศกษาระดบปรญญาตร มหาวทยาลยวลยลกษณ ประเทศไทย: การศกษาแบบภาคตดขวาง

Smoking and secondhand smoke remain major public health concerns, contributing to chronic diseases and long-term health effects, particularly among university students at risk of initiating smoking. Measurement of exhaled carbon monoxide (eCO) is a simple, rapid, and non-invasive method that reflects recent tobacco smoke exposure. This study aimed to assess smoking behaviours among 1st-4th year students at Walailak University—classified as active smokers, passive smokers, and non-smokers using a self-reported questionnaire—and to compare these findings with eCO levels measured by a portable breath analyzer (Smokerlyzer). A total of 346 consenting students participated in this cross-sectional study. End-expiratory carbon monoxide concentrations were measured, and questionnaire data were collected to assess smoking behaviours and common sources of carbon monoxide exposure. Smokers were classified as the carbon monoxide–exposed group and compared with passive smokers and non-smokers. All participants completed the questionnaire. Active smokers (n = 26) demonstrated significantly higher eCO levels than passive smokers (n = 62) and non-smokers (n = 258), with median levels of 4.00, 1.00, and 1.00 ppm, respectively. Receiver operating characteristic (ROC) analysis identified an optimal eCO cut-off value of ≥ 2.50 ppm for distinguishing smokers from non-smokers and passive smokers, with an AUC of 0.719 (95% CI: 0.605-0.833, p < 0.001), sensitivity of 87.50%, and specificity of 77.80%. Most smokers expressed an intention to quit, and many students supported implementing a tobacco-free campaign within the university. In conclusion, eCO measurement provides rapid and objective results that may reflect recent tobacco smoke exposure. Integrating eCO screening with education on smoking-related diseases and types of tobacco smoke may strengthen smoking prevention strategies and support the development of a tobacco-free university environment.