India, Nov. 7 -- Delhi's air quality remained in the 'very poor' category on Saturday morning, a day before Diwali, as a thick haze of pollutants enveloped the city.

The Air Quality Index (AQI) at 9.05 am stood at 364, according to data from the CPCB. At 53 of 59 air quality monitoring stations, PM 2.5 was the leading pollutant. Eighteen of the stations recorded air quality in the severe category.

The average AQI on Friday was on the brink of the severe category, at 382, prompting the CAQM to invoke GRAP III restrictions as a precautionary measure. The Air Quality Early Warning System has forecast that the air quality could slip into the severe category on Saturday and Sunday.

The CPCB classifies an AQI between 0 and 50 as "good", 51 a...