New Delhi, Dec. 15 -- The air quality index (AQI) readings at three of the Capital's monitoring stations maxed out at the 500-mark at various times on Sunday even as 38 of the 39 active stations hovered either in the "severe" or the "severe-plus" categories. The Centre for Pollution Control Board's 24-hour average AQI at the Wazirpur, Rohini, and Ashok Vihar stations reached 500. These apart, at least 13 recorded AQI levels above 490 for several hours on Sunday, with a few locations nearly maxing out. Among the worst affected areas were Jahangirpuri and Mundka - both recording an AQI of 499, Bawana (498), Delhi Technical University (497), Vivek Vihar (497), Narela (493), Anand Vihar (492), IHBAS in Dilshad Garden (491) and Okhla Phase-2 (49...