Delhi's air quality index (AQI) dropped to the 'very poor' category as a thick layer of smog covered the city on Sunday morning. According to Central Pollution Control Board (CPCB) data, Delhi recorded an overall AQI of 377 at 7 am. Wazirpur and RK Puram recorded AQI levels of 432 and 425, respectively, both falling in the 'severe' category.