Delhi's Air Quality Index (AQI) was recorded in the "moderate" category with a reading of 166, according to the Central Pollution Control Board (CPCB) at 9 am. An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".