Delhi’s AQI better but still in very poor zone

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Published on Dec 25, 2019 09:09 PM IST
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New Delhi:

With the winds picking up pace and the sun shining bright, air quality in the national capital improved marginally though remaining in the ‘very poor’ zone. It is expected to improve further over the next two days, monitoring agencies said.

The overall air quality index (AQI) as recorded by the Central Pollution Control Board’s (CPCB) 4 pm bulletin was 350 in the ‘very poor’ zone, as against 383, the previous day.

Scientists at the India Meteorological Department (IMD) said the wind was consistent throughout the day at a speed of 10-12kmph. Besides, the fog was not heavy in the morning hours, which allowed sunlight to reach the earth’s surface. Both these factors helped improve the air quality.

“Wind speed will remain good on December 26-27 as well. Delhi will have moderate fog on Thursday as well, which is less in comparison to ‘dense’ fog, which was being recorded over the past few days,” said a senior IMD scientist.

However, he said, the slight relief will be short lived as air quality may deteriorate from December 28-29 due to an increase in fog cover and reduced wind speed.

Delhi’s Jahangirpuri monitoring station had already entered ‘severe’ zone at 8 pm with an AQI reading of 403. The air quality is considered ‘severe’ when the AQI touches 401.

CPCB officials said they received some complaints of waste burning on its Sameer app. Small fires lit by people to keep themselves warm in the winter are recorded every winter, which may add to the deteriorating air quality.

The System of Air Quality and Weather Forecasting and Research (SAFAR), ministry of earth science’s weather and air quality monitoring centre, forecast also said that on Friday, the AQI is likely to reach the higher end of the ‘very poor’ category and will enter the ‘severe’ category over the weekend.

“The unusual spell of good wind speed that was keeping AQI in check so far is going to end. An extended period of calm surface winds with high humidity leading to shallow boundary layer height, which allows accumulation of pollutants, is forecast from December 27. It will touch the ‘severe’ category by December 28,” said a senior SAFAR scientist.

He said calm surface winds, low mixing layer and dense fog with high humidity are conditions highly favourable for the formation of secondary particulate (more potent and harmful than particulate matter), which could push up pollution levels even higher by the year-end.

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Monday, October 18, 2021