Seasonal variation of ambient air quality at selected sites in Agra city

127-133The seasonal variation in the ambient air concentration of SO2, NO2 and suspended particulate matter (SPM) in the urban atmosphere of Agra, India, during the year 1998-99, has been reported. The city was hypothetically divided into six monitoring zones. The maximum concentrations of SO2, NO2 and SPM were observed at Foundry Nagar and St. John's crossing. However, the minimum concentrations of SO2 and NO2 were observed at Dayalbagh, while the SPM concentration were minimum at Tajganj region. The value of SPM was always found higher than the prescribed limit of 100 μgm-3, while the values of SO2 and NO2 were found within the permissible limits, except sometimes in winter seasons, which may be due to thermal inversion. The value of monthly average pollutant standard index (PSI) has also been reported. The value varies from 127 to 497 in Agra