Background: Work-related stress and addictive behaviors have been characterized as potential impairers for the health, welfare and safety of workers. The aim of this study was to describe the relationship between work-related stress and the consumption of tobacco among city bus drivers, and the association of these two factors with the drivers’ rates of traffic incidents. Methods and Findings: For this study, 222 bus drivers responded to a questionnaire on individual work-related stress, self-rated lifestyle and health issues. Results showed that 21% of them were smokers, and 41% presented job strain. Significant associations were found between job strain and smoking, and between smoking and traffic incidents. Two patterns were identified in work-related stress and tobacco consumption, finding significant differences between them in traffic incident records. Conclusions: Considering the adverse results for these factors, interventions on work-related stress and lifestyle issues may strengthen the promotion of health and the prevention of traffic incidents among public transport workers.