I am doing PhD on Analysis of Impact of Urbanization on Climate and Air Pollution of Delhi and Mumbai Cities. I need station-wise daily and monthly average air pollutants data ( Co, Co2, So2, No, PM2.5, PM10, etc.) of Delhi and Mumbai for this. I tried various websites but I got data of after 2013. Data of years before are not available anywhere. Do anyone know have or know any website or source of the air pollutants data?