Air quality index of Delhi and NCR started increasing since November 2nd. The reason was the low temperatures associated with light and calm winds. Low temperature leads to the formation of mist and haze during morning hours and the pollutants of smoke particles, dust particles and harmful gases get deposited on the water vapor of mist and haze. In the absence of moderate winds, the pollutants remain suspended near the earth's surface leading to the formation of a layer of smog.
A western disturbance-induced cyclonic circulation formed over northwest Rajasthan and adjoining Pakistan on November 9. Widespread rain over the Northern Plains including Delhi and NCR leads to washing away of the pollutants. The air quality index of Delhi and NCR and adjoining parts of Northern Plains improved to the moderate category. AQI remained in moderate category until November 12th as the wind speed also picked up pace from Northwest direction.
The burning of firecrackers led to the deterioration of the air quality index of North India including Delhi from the night of November 12. There may be a marginal improvement in the AQI during the next 24 to 48 hours as wind speed may pick up the pace once again.
