The second half of November this year witnessed one of the cleanest period for Delhi NCR in term of air pollution. Air pollution level drops down to a satisfactory level first time during this winter. Between November 26 and 27 most of the localities of Delhi NCR witnessed AQI less than 100.
The credit for this improvement in the air quality index in November can be attributed mainly to the rainfall after Diwali in all areas of North India including Delhi. Due to these rain, the pollution of the atmosphere for most of the cities of North India including the national capital Delhi was cleared and the air quality improved. Usually after Diwali, because of the fireworks smoke dissolving in the air, the highest pollution of the year is recorded in the next day after Diwali. But this time due to the rain and the controlled fireworks, Delhi did not turn into a gas chamber. After this, the next round of rain was seen on 25 November when the increased wind controlled the increasing pollution and the people of Delhi got a chance to breathe clean air again.
But after November and the beginning of December, the wind speed over Delhi NCR reduced, due to which pollution started increasing again. By this time, the incidents of stubble burning in the neighbouring states of Delhi, including Punjab and Haryana, are stopped, due to which the smoke starts decreasing. But when the wind speed is low Delhi NCR's own pollution starts to make the air quality worse.
Meanwhile, a new western disturbance has moved closer to the hilly states of North India and due to this a cyclonic circulation has developed over the plains over western Rajasthan and adjoining Pakistan. Due to these systems, the wind direction has also changed and now eastern and southeastern winds have started moving instead of northwest. The speed of these winds is low and the humidity in these winds is high, due to which again the local pollution of Delhi and NCR has started coming to its true colour and the air quality has started deteriorating.
We forecast that air pollution in Delhi NCR will continue to be very high till 6 and 7 December, after which the western disturbance will overtake from 8 December and the northwest dry and cold winds will start moving over the plains of North India including Delhi and the air pollution will decline and the air quality will improve.
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