After 10 days, Delhi's air quality deteriorated to the "severe" category on Wednesday due to slow winds, government agencies said.
Stubble burning accounted for two per cent of Delhi's PM2.5 pollution on Wednesday.
According to the Central Pollution Control Board (CPCB) mobile app, SAMEER, the city's air quality index (AQI) was recorded at 401 on Wednesday morning and deteriorated to 415 in the evening. It was 388 on Tuesday.
It was 302 on Monday, 274 on Sunday, 251 on Saturday, 296 on Friday and 283 on Thursday.
The capital's AQI was in the "severe" category on November 15, a day after Diwali, but later improved and remained in either "poor" or "moderate" category until November 22.
An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".
According to Ministry of Earth Sciences' monitoring system SAFAR, stubble fire counts were quite low at 63 on Tuesday with its share in PM2.5 in Delhi's air at two per cent on Wednesday.
"Effective stubble fire counts with sufficient potential as estimated from SAFAR-multi-satellite products are low (around 63). Hence, the stubble burning share in PM2.5 in Delhi's air is estimated as two per cent for today,” it said.
“The AQI is forecasted to improve towards 'very poor' category by tomorrow and likely stay in the lower end of Very Poor on November 27 and 28,” SAFAR said.
Stubble burning accounted for five per cent of Delhi's PM2.5 pollution on Tuesday, six per cent on Monday and 12 per cent on Sunday. It was 13 per cent on Saturday, 15 per cent on Friday and 20 per cent on Thursday.
The maximum and minimum temperatures in the city on Wednesday settled at 24.4 degrees Celsius and 10.4 degrees Celsius with cloudy sky.