Slight let-up in Delhi's AQI as farm fires remain low

NEW DELHI:  Air quality in the national capital improved slightly to settle into the ‘very poor’ zone from ‘severe’ the previous day. Even though the pollutant cover settled about 1 km from the earth’s surface, resulting in poor ventilation, external emissions such as smoke from farm fires remained low that helped improve the air quality in the city, said weather experts.

Also, Delhi saw its coldest morning of the season on Wednesday, November 17, 2021, with the minimum temperature dropping to 9.6 degrees Celsius. As per the Central Pollution Control Board (CPCB), Delhi’s overall air quality index (AQI) was 375 in the ‘very poor’ zone, as against 403 in the severe zone, the previous day. As per the Union ministry’s System for Air Quality and Weather Forecasting and Research (SAFAR), air quality is likely to remain the same over the next two days.

“While transport level winds are coming from the east direction preventing intrusion of pollutants from the upwind region, local surface winds are low and mixing layer height is about 1 km resulting in poor ventilation of near surface pollutants,” it said. As per the India Meteorological Department (IMD), with a dip in mercury combined with low surface winds and a transition likely to take place in the wind direction on Thursday, which anyways slows down winds, any significant improvement in air quality was not likely at least till November 20.

A senior IMD scientist said, “The wind direction is likely to change to southeasterly from northwesterly at present. Whenever there is a transition in wind direction, winds become calm, which is not favourable for dispersion. Besides the drop in temperature only makes the air heavier, which further traps pollutants.”
Mahesh Palawat, VC of Skymet, a private weather forecaster, also said that while northwesterly winds are cold and dry, southeasterly winds are warmer and humid.

“The southeasterly winds are likely to begin blowing over Delhi from November 18 and stay till November 20. Since these winds are variable, the speed is not much and remains less than 10 kmph unless there is some strong weather system forming.

On November 20, there will be cloud cover as well, which combined with these winds will allow the night temperature to rise up to 12 degrees C. There might be some dispersion around this time. The northwesterly winds are likely to return to Delhi from November 21-22, with which the mercury will again see a gradual drop and the night temperature may fall to 8 degree C,” said Palawat.

Key decisions taken to combat pollution

1. All construction and demolition activities are banned till Nov 21
2. All schools, colleges and educational institutions closed till further orders
3. 1,000 private CNG buses will be hired to strengthen the public transport system
4. All industries using unapproved fuels to be closed with immediate effect
5. Only 5 of 11 thermal power plants within 300 km of Delhi will remain operational till Nov 30
6. Work from home for 50 per cent of govt employees in offices in NCR till Sunday 
7. Trucks carrying non-essential items banned from entering Delhi till Sunday
8. Machines of the fire brigade will sprinkle water at 13 pollution hotspots 
9. Diesel and petrol vehicles older than 10 years and 15 years, will be stopped from plying roads

UP gets its first pollution control tower in Noida
Uttar Pradesh’s first air pollution control tower opened in Noida on Wednesday, officials said. Located in the posh Sector 16A, the 20-metre-high tower with a diameter of nine metres can filter air in an area of one square kilometre around it, they said. The tower has come up with joint efforts of the BHEL and the Noida Authority, the officials added. It was inaugurated by Union Heavy Industries Minister Mahendra Nath Pandey in the presence of minister Krishna Pal, Gautam Buddh Nagar MP Mahesh Sharma, Noida MLA Pankaj Singh and Noida Authority CEO Ritu Maheshwari.