Title: Health risks of atmospheric BTEX at an urban roadside of a north Indian terai region

Abstract

Volatile organic compounds (VOCs) in the ambient air are of great concern because of their potential health impacts, formation of organic aerosols, photochemical smog production, and so on. Benzene, toluene, ethylbenzene and m-, p-, o-xylene (BTEX) are the most typical components of VOC pollution in air. Over the last few decades, there has been a dramatic increase in the number of publications on traffic-related volatile organic compounds (VOCs), which indicates that automobiles in urban regions are the dominant source of BTEX. A monitoring program was designed and implemented to characterize roadside levels of BTEX during November, 2017 – February, 2018 at Gorakhpur – a terai belt of north India, on both weekdays and weekends. Samples of the air were collected at two sites namely, Nausad Traffic Junction (NTJ) and Golghar Traffic Junction (GTJ). Besides this, air samples were also collected at different distances (3m, 10m, 20m, 30m respectively) from the road. BTEX were sampled by SKC activated charcoal tubes and analyzed by GC– FID (Gas Chromatography- Flame Ionization Detector). Few of the samples were also monitored in semi-continuous mode by using ion science phocheck+ (Tiger) photo ionization detector (PID). Total BTEX concentration ranged from 8.9 - 63.1 µg m-3 at roadside sites, Gorakhpur. The total mean BTEX at Golghar Traffic Junction (GTJ) and Nausad Traffic Junction (NTJ) were 33.2 µg m-3 and 16.1 µg m-3 respectively. The concentrations of BTEX were plotted against distance from the road. The estimated integrated lifetime cancer risk (ILTCR) for benzene and ethylbenzene exceeded the threshold value of 1E-06, whereas the individual hazard quotients (HQ) did not exceed unity. The higher traffic volume and traffic congestion on weekdays lead to remarkably higher BTEX levels than those observed on Sunday at both the sites. Toluene was found to be dominant followed by benzene, xylene and ethylbenzene. Appropriate traffic management and vehicle emission control should be applied to reduce the VOC pollution in the city.