Concentrations; Winds; Frequency; Winter and monsoon
A study of concentrations of sulfur dioxide (SO2) and suspended particulate matter (SPM) has been performed in Delhi. The monthly and seasonal variations of concentrations and winds are analyzed. The monthly mean SO2 concentrations were in the range of 16.15–34.44 μg m−3 and showed regular seasonal variations with the highest concentrations in winter and lowest in monsoon season. On the other hand, the monthly mean SPM concentrations reached the highest (465.68 μg m−3) in November and the lowest (150.07 μg m−3) in August. It was observed that high SO2 concentrations were generally associated with the wind blowing from WNW–NW directions, and the high SPM concentrations were usually related to the wind blowing from W–NW directions.