In the last three last decades air pollution level has been increased significantly especially in the northern parts of India with Delhi being the most polluted city. Population growth, energy demand, industrial growth, increased crop burning, increased traffic density and coal burning have affected the air quality of Delhi and surrounding areas upto a great extent. In the present paper, we have used MODIS Terra and Aqua data to study the annual and seasonal variations of Aerosol Optical Depth (AOD) and Angstrom Exponent (AE) and also tried to identify the sources of pollution based on AOD and AE. A wide variation in AOD, (range 0.07 to 3.49) and AE, (range 0-1.8) is observed during 2000-2019 over Delhi and surrounding regions. This shows very poor air quality and highly polluted atmospheric. Different aerosol types are found to be season dependent based on the detailed analysis of AOD and AE retrieved from satellite data during the period 2000-2019. The present analysis shows dominance of anthropogenic aerosols (AA) during winter whereas biomass burning (BB) during post monsoon seasons. During pre monsoon season pollutant continental (PC) and mostly dust (MD) were observed for many days as air mass travel from Thar Desert, Middle East and Arabia with the westerly winds. In the recent decade, clean days in Delhi are reduced significantly.