The 24-hour average air quality index (AQI) in Delhi was in 'severe' category as the national capital recorded an average AQI of 426 at 9.10 am on Tuesday, according to Central Pollution Control Board's data. Meanwhile, the AQI in Gurugram was 399, while it was 397 in Noida. Some relief is expected from November 2, a senior SAFAR official said.