Delhi’s air quality remained ‘very poor’ on Thursday, with seven areas recording ‘severe’ air quality. The Central Pollution Control Board listed an overall air quality index (AQI) of 355. An AQI between 201 and 300 is considered ‘poor’, 301 and 400 ‘very poor’ and 401 and 500 is ‘severe’. A CPCB task force has identified 21 high pollution hotspots in Delhi-NCR and directed the respective municipal corporations to take “focussed action”.
Source : https://www.thehindu.com/todays-paper/tp-national/air-quality-very-poor-in-delhi/article25684231.ece