Capital city's air quality index stood at 366 at 1 p.m., in the very poor category. Anand Vihar area is the worst affected, while Lodhi Road the least.
According to the System of Air Quality and Weather Forecasting And Research (SAFAR), stubble fire counts have significantly jumped and stood at 3,471, the highest so far this season, as on Friday.
"Yesterday, we observed the highest fire count of this season over Punjab area. This impacted the air quality over Delhi-NCR," Vijay Soni, a scientist at the air pollution division of India Meteorological Department (IMD) told IANS.
"Now the wind, as well as ventilation co-efficient, is favourable for improvement of air quality. We are expecting that tomorrow and day after that, the air quality will improve," Soni added.
Besides, SAFAR officials said that the boundary layer wind direction continues to remain favourable for pollutant transport towards Delhi. Due to this, stubble burning share in PM2.5 has increased and is estimated at 32 per cent.
The maximum share of stubble burning to Delhi's air was recorded on Thursday at 36 per cent.
"Improvement has not happened in spite of much better ventilation, mainly because of highly favourable North-North-Westerly boundary level wind direction and perfect wind speed for intrusion in Delhi combined with season's highest fire count," the agency stated.
"Increased local surface wind speed with faster dispersion conditions are counteracting with increased fire-related emission and associated instruction.
"However, AQI is likely to improve for the next two days as dispersion will eventually play a lead role," it also said.
According to the Central Pollution Control Board (CPCB), four of the 36 pollution monitoring station in Delhi showed 'severe' air quality index reading. Delhi's Anand Vihar area recorded the worst air quality index at 448, which falls in the 'severe' category.
Besides these, 31 pollution monitoring station showed 'very poor' reading and one, Lodhi Road station, logged a moderate air quality index.
Delhi's neighbouring regions -- Gurugram, Ghaziabad, Faridabad, Noida and Greater Noida -- also recorded 'very poor' quality of air. Ghaziabad and Gurugram air quality remained the worst among all.
To tackle the air pollution, President Ram Nath Kovind on Wednesday signed an ordinance brought in by the Centre for a Commission to manage air quality in the National Capital Region.