Delhi’s air quality remained “poor” on Sunday and government agencies said it was likely to deteriorate further due to unfavorable weather conditions. The city’s 24-hour average AQI was 274 on Sunday, 251 on Saturday, 296 on Friday, 283 on Thursday, and 211 on Wednesday.
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”. The central government’s Air Quality Early Warning System for Delhi said Delhi-NCR’s air quality is likely to deteriorate to the “very poor” category on Monday due to unfavorable weather conditions.
The predominant surface wind direction was northwest and the maximum wind speed was 12 kmph on Sunday, he said, adding that the wind speed was likely to drop to 8 kmph on Monday. The central agency said the AQI is likely to deteriorate to the upper end of the “very poor” category between Tuesday and Friday.
Up to 649 counts of agricultural fires were observed in Punjab, Haryana and adjacent regions on Saturday, according to the air quality monitor of the Ministry of Earth Sciences, SAFAR. Stubble burning accounted for 12 percent of Delhi’s PM2.5 pollution on Sunday. It was 13 percent on Saturday, 15 percent on Friday, 20 percent on Thursday, and eight percent on Wednesday.
The minimum temperature was set at 6.9 degrees Celsius on Sunday, the lowest in November in 17 years, according to IMD. Calm winds and low temperatures trap pollutants close to the ground, while favorable wind speeds help disperse them.
Delhi’s ventilation index, a product of mixing depth and average wind speed, was around 6,500 m2 / s on Sunday and is likely to drop to 1,500 m2 / s on Monday and Tuesday. Mixing depth is the vertical height at which contaminants are suspended in the air. Reduce on cold days with calm wind speeds.
A ventilation rate of less than 6,000 m2 / second, with an average wind speed of less than 10 km / h, is unfavorable for the dispersion of pollutants. Hours earlier, Delhi Environment Minister Gopal Rai said the Department of Public Works has installed 23 anti-smog guns and deployed 150 tanker trucks to spray water at key intersections and construction sites to reduce dust pollution.
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