Tehran geographical zoning in respect to air pollution

The present study aims at investigating the zoning of Tehran according to the most severe polluted days. In this regard, 100 days with the highest pollution level recorded by the stations were selected from 2004 to 2008 in five selective stations around the city and the zoning progress was done based on them. In respect to co.PM10 and SO2 level, Azadi station was the most polluted and Sarkhehesar and also Ray town were the cleanest regions. Considering the NO2, Ray station was the most polluted and Sarkhehesar station was the cleanest one. Regarding O3, Ray station was the most polluted and Pardisan was the cleanest one. Despite the fact that the wind direction was from west to east, wind flow has no a considerable effect on air purification because of the high density of the buildings and low speed of wind. The findings revealed that pollution level in center and west is more than east. Likewise, pollution concentration level of O3 and NO2 increase and pollutant concentration levels of SO2, PM10and CO decrease from north to south of Tehran.