New delhi: While Delhi had managed to enjoy relatively clean air two days after Diwali, the city's air remained "poor" on Thursday as farm fires in the neighbouring states went up, contributing to 20 per cent of the city's pollution.
Government agencies said the air quality may dip to the "very poor" category on Friday and improve slightly on Saturday due to favourable surface wind speed. Delhi's 24-hour average air quality index was recorded at 283. It was 211 on Wednesday and 171 on Tuesday.
According to the Ministry of Earth Sciences' air quality monitor, SAFAR, stubble burning accounted for 20 per cent of Delhi's PM2.5 pollution on Thursday. It was 8 per cent on Wednesday and 3 per cent on Tuesday. A total of 967 fire fires were observed in Punjab, Haryana and western Pakistan on Thursday, it said.
The central government's Air Quality Early Warning System for Delhi also said Delhi-NCR's air quality is likely to remain in the "poor" to the lower end of the "very poor" category on Friday. SAFAR also said the conductive meteorological environment created after rainfall is slowly retreating and a deterioration in the air quality is likely.
The minimum temperature settled at 9.4 degrees Celsius on Thursday — the lowest this season so far —and the maximum wind speed was predicted to be 10 kmph, according to the India Meteorological Department. Calm winds and low temperatures trap pollutants close to the ground, while favourable wind speed helps in their dispersion.
The IMD had earlier said the minimum temperature in Delhi will drop to 9 degrees Celsius by Saturday, as cold winds have started blowing from hilly regions, which have witnessed a fresh bout of snowfall.
The minimum temperature this month, barring on November 16, has remained 2-3 degree Celsius below normal in the absence of a cloud cover, according to IMD officials.
Normally, the Safdarjung Observatory, which provides representative data for the city, records a minimum of 12.3 degrees Celsius from November 19 to November 21. The average minimum temperature from November 22 to November 26 is 11.3 degrees Celsius, according to the India Meteorological
Department.