The air quality in Delhi was close to 'severe' mark on Sunday with Air Quality Index (AQI) reaching 391, according to the Central Pollution Control Board (CPCB). A layer of smog blanketed the national capital. Bawana, Burari, Ashok Vihar, Alipur and Anand Vihar saw 'severe' air with AQI at 436, 430, 416, 414, and 416 respectively.