The Air Quality Index (AQI) in Delhi was recorded in the 'very poor' category at most of the stations, at few places like Dwarka Sector-8 and Patparganj, Alipur, Shadipur, DTU and Panjabi Bagh, it had crossed the 400-mark, going into the 'severe' category, according to data shown in SAMEER app. For three consecutive days, the air quality of Delhi has remained in the 'very poor' mark.