The air quality in Delhi continues to be in the 'Severe' category as per the Central Pollution Control Board (CPCB) on Thursday. The city's 24-hour average Air Quality Index (AQI), recorded at 4 pm every day, stood at 426, worsening from 395 on Tuesday. To curb the deteriorating air quality, schools across the city will be closed for their winter break from today, November 9 until November 18.