Evaluation of Cognitive Performance of City Bus Drivers with Respect to Noise and Vibration Exposure

During daily work, bus drivers are exposed to various environmental factors, and their mental responses to these risk factors are still poorly understood. This study aimed to investigate the cognitive performance of bus drivers with respect to noise and vibration exposure. The study was conducted in 103 healthy city bus drivers. Based on their work schedule, the drivers' exposure to noise and vibration was measured using the Svantek SV 104 noise dosimeter and the SV 106 vibration meter, respectively. The simple Stroop test was used to measure drivers' selective attention capacity and skills as cognitive performance indicators. Drivers' job stress was determined using a standard questionnaire. The drivers' exposure levels to noise, whole-body vibration, and hand-arm vibration was 79.50 ± 3.51 dB, 0.620 ± 0.159 m/s², and 0.438 ± 0.064 m/s², respectively. Significant differences were observed in the interference score (IS) and interference time (IT) after driving (p < 0.05), which indicates a decrease in the number of true responses and an increase in response time. The multiple linear regression model showed that noise and vibration, as main environmental stressors in the presence of other individual's covariates such as age, work experience, and job stress, have significant effects on cognitive performance based on changes in IS and IT during driving (model accuracy; r = 0.61 and r = 0.57). The traffic load was also significantly associated with changes in IS and IT (p < 0.05). The possibility of mental function loss while driving indicates that appropriate occupational health surveillance must be implemented for bus driving occupations.