Stubble burning in neighbouring states of Delhi on Thursday was the "largest-ever recorded" this year which might lead to a further deterioration in the already "severe" air quality of the national capital, a government-run agency said Friday.
According to the Indian Institute of Tropical Meteorology, 2,100 fire counts were observed on Thursday over north western region of India.
"It was the largest-ever recorded for this year. It was around four times higher than Wednesday," IITM said.
"The PM2.5 concentration is likely to increase again from Friday afternoon and may remain severe or severe-plus in Delhi-NCR till Sunday," it said.
The increase in PM2.5 (particles in the air with a diameter of less than 2.5 micrometres) concentration would be due to "stable" meteorological conditions, trapping the polluted air-mass in Delhi and significant increase in contribution from biomass burning, IITM said in a report.
The Centre-run System of Air Quality and Weather Forecasting And Research (SAFAR) too warned that Delhi's air quality would remain in the severe category till Saturday as the toxic smoke smoke from fireworks is likely to aggravate due to intensified stubble burning in neighbouring states.
Stubble burning in neighbouring states combined with localised factors in Delhi such as vehicular emissions, industrial pollution and smoke from firecrackers around Diwali every year plague the national capital's air quality every year.
This year too, the pollution level spiked to severe-plus emergency levels due to rampant burning of firecrackers leading to the formation of a smoky layer across Delhi.
Delhi's air quality on Thursday went off the charts as smog caused due to smoke from firecrackers engulfed the national capital.
The overall AQI Thursday was recorded in the "severe plus emergency" category at 642. On Friday, the AQI was recorded at 421, which falls in the 'severe' category, according to the the Central Pollution Control Board.