India, Dec. 14 -- A thick layer of toxic smog blanketed Delhi on Saturday, with the air quality index slipping into the 'severe' category at 431, the worst recorded so far this year.

The 24-hour average air quality index (AQI) stood at 431, according to the Central Pollution Control Board (CPCB), while the Air Quality Early Warning System predicted the AQI to remain 'severe' on Sunday as well.

Saturday recorded the worst air quality of the year so far, surpassing the earlier high of 428 recorded on November 11, official data showed.

Among the Delhi-NCR cities, Delhi's AQI was the third worst after Noida at 455 and Greater Noida at 442, reflecting severe air pollution across the region.

The Air Quality Early Warning System said conditi...