NEW DELHI: Winds dying down in Delhi again pushed air quality to the ‘severe’ zone on Tuesday, November 16, 2021. Also, the city saw its coldest morning of the season on Tuesday, with the minimum temperature falling to 10 degrees Celsius.
The air quality is likely to deteriorate till November 18, owing to calm wind conditions and drop in mercury even though stubble burning impact is lesser because of changed winds, said weather experts. As per the Central Pollution Control Board (CPCB), Delhi’s air quality index (AQI) was 403 in the ‘severe’ zone, as against 353 in the ‘very poor’ zone on Monday.
As per the India Meteorological Department (IMD), calm wind conditions in Delhi and surrounding areas is not letting enough ventilation for accumulated pollutants to disperse. “Wind speed during the day is 4-5 kmph for a few hours and it dies down by evening. While there is little or no dispersion, daily emissions are getting added to the already stuffy atmosphere and so the spike in pollution levels,” said a senior IMD scientist.
The Safdarjung Observatory, representative of Delhi’s weather, on Tuesday recorded the season’s lowest minimum temperature — 10 degrees — four notches below normal for this time of the year. “Minimum temperature can drop to 9 degrees C by Wednesday. Cold air is heavier which further traps pollutants and with no winds blowing, there is no dispersion,” the official added. As per the Union ministry’s System for Air Quality and Weather Forecasting and Research, winds are likely to be very calm with a low ventilation index pushing air quality to ‘severe’. The AQI will fluctuate between ‘severe’ and upper end of ‘very poor’ till November 18.
“Intrusion of stubble burning related pollutants into Delhi is not likely for next two days due to unfavourable (winds coming from east) transport level winds. The farm fire count has reduced to 1,820 and its contribution to Delhi’s PM 2.5 today is 8 per cent. The peak in fire count appears to have reached last week and it is now starting to decline, which got delayed by about a week due to late withdrawal of the monsoon,” it said.