India, Dec. 8 -- The air quality in the city remained in the "very poor" category on Sunday and is expected to remain in the zone throughout the week. The 24-hour average air quality index (AQI) was recorded at 308 on Sunday, as per the Central Pollution Control Board's 4pm data. It was 330 (very poor) on Saturday.

Delhi's air quality has largely stayed in "very poor" range this winter, with three consecutive "severe" air days between November 11 and 13. Forecasts by the Centre's Air Quality Early Warning System (EWS) for Delhi shows the AQI should firmly stay "very poor" in the days ahead.

According to categorisation by the CPCB, an AQI reading between 0-50 is "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "...