<sec> <title>Objectives</title> <p>To examine the factors affecting passive exposure to secondhand smoke (SHS) in non-smoking student nurses.</p></sec> <sec> <title>Methods</title> <p>A cross-sectional study was performed in 196 college students who had not smoked cigarettes in the past 12 months. Urinary cotinine levels were examined to identify exposure to SHS, and social factors were identified that influenced exposure to SHS, including requests that smokers extinguish cigarettes. Logistic regression analysis was used to predict the factors influencing SHS.</p></sec> <sec> <title>Results</title> <p>Urinary cotinine measurements showed that 32 students (16.3%) were exposed to SHS. Risk factors that increased exposure to SHS affected 80 students (40.8%) in the previous 7 days. Students who were exposed to SHS were 4.45-times more likely to have increased urinary cotinine levels than those who were not exposed. Students who asked others to extinguish their cigarettes were 0.34 times less likely to test positive than those who did not.</p></sec> <sec> <title>Conclusion</title> <p>Urinary cotinine was a useful biomarker for identifying exposure to SHS, with respect to the influence of demographic, health-related, and smoking-related factors. In non-smoking nursing students, avoiding exposure to SHS was attributed to self-assertive behavior by requesting smokers to extinguish cigarettes.</p></sec>