Occupational exposure of vehicular emissions and cardiorespiratory risk among urban metropolitan bus drivers: A cross-sectional comparative study

Abstract

BACKGROUND: Vehicular emissions on long-term exposure predispose metropolitan bus drivers to cardiorespiratory ailments. OBJECTIVE: To evaluate the cardiorespiratory risk of urban metropolitan bus drivers related to vehicular emission exposure. METHODS: Bus drivers (with service >5 years, n = 254) and their administrative controls (primarily engaged in indoor white collared jobs, n = 73) were recruited. Demographic, occupational and clinical details were collected through pre-validated standardized format. Pulmonary Function Test (PFT) and lipid profile were carried out with standard protocol. Risk for cardiovascular events for preceding 10-years was estimated with WHO/ISH risk prediction chart and QRISK3 score. Exposure assessments for particulate matter (PM) were performed for both groups while duty hours. RESULTS: Exposure of drivers to PM2.5 six times and PM10 five times higher in comparison to administration staff (PM2.5- 970.9 v/s 145.0μg/m3 TWA and PM10- 1111.7 v/s 233.8μg/m3 TWA). Bus drivers exhibited significantly higher prevalence of respiratory symptoms (dyspnea-25% v/s 6.8% and cough-20.1% v/s 9.8%) and compromised PFT (obstructive–21% v/s 5.7% and restrictive–4.2% v/s 2.9%) in comparison to controls. Multivariate regression statistics reveal a significant decline for FEV1/FVC and FEV25–75 % among bus drivers compared to controls, controlling the influence of physiological and environmental factors. The difference between predicted cardiac age and their respective chronological age was twice higher (8.3 v/s 4.3 years) among drivers compared to their administration staff. CONCLUSION: Bus drivers were exposed to high levels of outdoor air pollutants. Further, the drivers exhibited higher risk for ischemic attack and obstructive airway diseases as compared to administration staff.