No respite for Delhi, AQI ‘severe’ for third day in a row | Delhi News

Data shows that this ‘severe’ air spell in the first week of November has persisted at least from 2019 onwards.

The 24-hour average AQI at 7 pm on Saturday was 433, having deteriorated from a figure of 407 at 9 am. This was only slightly lower than the peak of 475 recorded on Friday, the highest so far this season.

Meteorological factors that have been preventing the dispersion of pollutants and keeping visibility poor from Thursday onwards, remained unchanged on Saturday.

According to a scientist at the India Meteorological Department (IMD), calm conditions prevailed at the Safdarjung weather station, where the visibility was only 500 m at 7 am and improved only marginally to 600 m around 4 pm. Low wind speed of 4 kmph from the Northwest direction prevailed at Palam, where the visibility was 400 m at 7 am and 1,000 m at around 4 pm.

‘Severe’ AQI is likely to continue since low wind speed, along with winds from the northwest or north of Delhi that could bring stubble-burning smoke into the national capital, is set to prevail at least till November 7, the forecast indicates. The wind direction is likely to be from the northwest or north directions of Delhi with a low speed of 6 to 8 kmph on Sunday. The wind speed could remain the same on Monday, with wind direction from the northwest or northeast.

Meanwhile, instances of stubble burning in Punjab remained above 1,000 for the seventh consecutive day on Saturday, with a fire count of 1,360, according to data from the Indian Agricultural Research Institute (IARI). The count in Haryana is down to 33, having peaked at 127 on October 15.

Last year, in the first week of November, the AQI remained ‘severe’ on November 1, 3 and 4, going by Central Pollution Control Board (CPCB) bulletins.

In 2021, there was a three-day spell of ‘severe’ air days in the first week of November, from the 5th to 7th. In 2020, there was a similar three-day spell from November 5 to 7 in the first week, and this extended into the second week, till November 10. In 2019, there were three ‘severe’ air days in the first week of the month – November 1, 3 and 4. In 2018, there was just one such day on November 5.

The average AQI in November 2022 (320) was lower than it was in 2020 (328) and 2021 (377).

While pollution levels spike in winter, the sharpest rise is usually seen in November. Data from the Centre for Science and Environment (CSE) on the daily average PM 10 and PM 2.5 levels for the winter (October to January) from 2018-19 onwards shows that the daily average particulate matter level hits the highest daily figure in November, except for 2018 when December recorded a higher PM10 level.

From 2019 onwards, Diwali — when firecracker emissions also contribute to rise in pollution levels — has fallen in the first week of November only in 2021, while it was on November 7 in 2018.

“Broadly, around this time, the levels begin to increase. This kind of sudden spiral and trapping of pollutants happens because of the meteorological conditions and then you have crop residue burning,” said Anumita Roychowdhury, executive director, research and advocacy, CSE.