Evaluation of In-Vehicle Pollutants Exposure and Respiratory Symptoms among Bus Drivers in Kota Bahru, Malaysia

Abstract

Abstract Exposure to in-vehicle air pollutants has been recognized as a risk factor for respiratory diseases. The present study, therefore, investigates the factors, including duration of employment and in-vehicle concentrations of fine particulate matter (PM2.5), carbon dioxide (CO2) and nitrogen dioxide (NO2) that can influence the prevalence of respiratory symptoms in commercial bus drivers. A total of 34 bus drivers and 51 administrative staff (comparative group) from the bus operator in Kota Bahru, Malaysia were randomly enrolled in this cross-sectional study. The personal characteristics and respiratory symptoms were reported using a validated questionnaire from the American Thoracic Society (ATS-DLD-78-A). In-vehicle concentrations of PM2.5, CO2 and NO2 were continuously measured over eight hours on each bus driver. The prevalence of self-reported cough, phlegm and chronic phlegm among bus drivers were 55.9%, 73.5% and 35.3%, respectively, significantly higher compared to the comparative group (p < 0.001). Moreover, the duration of employment with bus operators for more than four years was significantly related to the manifestation of phlegm (OR = 8.27, 95% CI = 3.12-21.89) and cough (OR = 4.57, 95% CI = 1.66-12.59). Among the pollutants measured, concentrations of PM2.5 (92.1 µg/m3) and CO2 (286.9 ppm) inside the buses were significantly higher in the morning compared to afternoon hours (p < 0.001). These findings provide important evidence for further surveillance programs that could reduce occupational exposure for bus drivers.