Air pollutant concentrations in Varanasi, India

This study reports the diurnal patterns in the concentrations of ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and total suspended particulate matter (TSP) in the urban atmosphere of Varanasi city in India during 1989. The city was divided into five zones and three monitoring stations were selected in each zone.
Ambient concentrations of NO2 and SO2 were maximum during winter but ozone and TSP concentrations were highest during summer. The measured maximum concentrations (2-h average) were 150 and 231 [mu]g m-3 (0.078 and 0.086 ppm) for NO2 and SO2, respectively, for the winter season. Ozone and TSP concentrations reached a maximum of 160 (0.08 ppm) and 733 [mu]g m-3, respectively, in the summer. NO2 and SO2 concentrations peaked in the morning and evening. Peak concentrations of O3 occurred in the afternoon, generally between noon and 4 p.m. Maximum concentrations of O3, NO2, SO2 and TSP were measured in zones I and II, and minimum in zone V.