Air quality index in Delhi on Friday continued to deteriorate to reach the worst 'Severe' category, according to the Central Pollution Control Board (CPCB). It said that Air Quality Index is at 422 in Anand Vihar, 407 in RK Puram, 421 in Sector 8 of Dwarka, and 430 in Bawana. At ITO, the board said that AQI was 448. All are in the 'Severe category'. According to the Meteorological Department, the AQI level is going to remain the same for a week.