The air quality in Delhi was “very poor” on Saturday, with the air quality index at 395 at 9 am, according to data from the Central Pollution Control Board. The Centre-run System of Air Quality and Weather Forecasting And Research recorded the overall AQI as 453, which falls under the “severe” category.

The air quality in some locations in Delhi were “hazardous”, according to aqicn.org. Siri Fort, Srinivasapuri near PGDAV college, Major Dhyan Chand National Stadium and Parparganj showed high levels of pollution.

Central Pollution Control Board data showed that the air quality index value for Friday was 423, which falls under the “severe” category.

According to SAFAR, PM 2.5 (particles with a diameter of less than 2.5 micrometres) was recorded at 303, while PM 10 was at 440 – both in “severe” categories. The research centre’s bulletin for Friday said the air quality in Delhi has improved significantly compared to Thursday, when it reached the “severe plus” emergency category because of smog caused by firecrackers burst during Diwali.

The recovery is slow due to surface wind speed and it continued to be in the severe category, it said. “There is a possibility that wind may pick up at upper level, late in the night and push the level of pollution and keep it in severe zone tomorrow [Saturday] with intensified fog which will further help in trapping the pollutants,” the bulletin said.

“The concentration of PM 2.5 is likely to shoot up over the weekend,” an unidentified scientist working with Delhi’s early warning system told Hindustan Times. “Its levels could breach the severe or emergency category. Such conditions are likely to linger till Sunday.”

Lodhi Road area recorded an increased PM 2.5 concentration, reported The Indian Express. The air quality is expected to remain in the ‘severe’ category. According to The Indian Institute of Tropical Meteorology (IITM), stubble burning was the “largest-ever recorded” for this year with 2,100 fire counts, which might lead to a further deterioration of the already “severe” air quality of the national Capital.

Meanwhile, over 400 heavy and medium goods vehicles were refused entry into Delhi after a ban was enforced on Thursday on their entry to check pollution.