Author(s): AK. Singh, Neetu Tomer, CL. Jain
ABSTRACT Volatile Organic Compounds (VOCs) present in ambient air are potentially toxic among the air pollutants. They are present in the urban atmosphere in both exhaust and evaporative emission from vehicles and the fuel delivery outlets. The present study aims the measurement of VOCs (Benzene, Toluene and Xylene) concentration and to investigate their existing profiles in the urban environment of Delhi, India. The samples were collected by active sampling on to activated charcoal tube using a portable constant low flow volume sampler. Sampling flow rate ranged 20-25 ml/min and sampling duration 150-180 minutes. The samples were analysed by capillary Gas Chromatograph (GC) followed by desorption of adsorbed VOCs in conventional solvent carbon disulphide (CS2). The external calibration was performed by using five concentration level of standard solution in CS2. The Benzene, Toluene and Xylene concentration ranged between 4.90-25.28µg/m3, 14.93-87.33µg/m3 and 6.92- 24.75µg/m3, respectively in different land used areas (residential, commercial, industrial, traffic-intersection and near gasoline filling station etc.). The present study indicates that the mean concentration of VOCs (BTX) at all sites were found higher than the limiting value prescribed by central pollution control board (i.e. 5µg/m3, annual average for benzene). This indicates that in the urban atmosphere BTX do not dissipate easily in the environment and therefore needs serious thought for reduction.