A thick layer of smog covered Delhi on Sunday as the national capital recorded ‘very poor’ air quality, with an overall AQI of 390 at 7 am, according to Central Pollution Control Board (CPCB). Several areas reported ‘severe’ air quality levels, including Akshardham (438), Ghazipur (438), and ITO (405). Notably, GRAP-4 anti-pollution measures are already imposed in the national capital.