Delhi’s air quality took a turn for the worse Wednesday with the city’s air quality slipping into the severe zone, with its AQI recording 401 at 6am.

On Tuesday, the city’s air quality index (AQI) had settled at 379, in very poor zone, according to the 24-hour rolling average of Central Pollution Control Board (CPCB) recordings at 4pm. On Monday, the AQI was in the same range but with a lower reading of 302. Government agencies forecast that the air quality could enter severe zone on Wednesday.

On Wednesday, the minimum temperature recorded at the Safdarjung observatory was 6.7 degrees Celsius, nearly four degrees below the season’s normal.

Government data on farm fires and experts indicated that the current deterioration in Delhi’s air was largely due to weather conditions adverse to the dispersal of pollutants and local pollution sources (such as road and construction dust, vehicular emissions and garbage burning), reaffirming the argument that the root of the city’s annual ordeal goes beyond firecracker bursting on Diwali and burning of crop stubble in neighbouring states — two of the factors widely cited for the grim AQI readings in October-November.