24-day streak of ‘very poor’ air in Delhi ends

The brief improvement snapped the 24-day stretch between November 6 and 29, when air quality stayed above 300 everyday.

Strong northwesterly winds brought small respite the Capital on Sunday, ending the 24-day streak of ‘very poor’ air — albeit just for the time being.

A clear sky seen over Kartavya Path on Sunday evening. (Arvind Yadav/HT Photo)

On Sunday, the city recorded an air quality index (AQI) of 279 (poor), improving from the 305 (very poor) a day earlier.

Experts attributed clearer skies in parts of the city and better AQI to strong winds. “We had strong northwesterly winds blowing from the mountains towards the plains, which helped in dispersion of pollutants not just across Delhi but Punjab and Haryana too. AQI began to improve from Sunday night onwards,” said Ashwary Tiwari, who runs the IndiaMetSky portal on X.

Data by the Central Pollution Control Board (CPCB) shows that winds picked up from Saturday afternoon, clocking speed of 10–15 km/hr through the day and preventing night-time stagnation. Experts said this consistent wind flow helped disperse pollutants that had accumulated over the past three weeks.

The brief improvement snapped the 24-day stretch between November 6 and 29, when air quality stayed above 300 everyday. The same period also recorded three ‘severe’ days — from November 11 to 13.

The marginal recovery, however, may be short-lived. Forecasts indicate that pollution levels are likely to inch back to the “very poor” category over the coming days. The Air Quality Early Warning System for Delhi (EWS) has projected a slide back into the “very poor” range from Monday, with AQI expected to stay above 300 for the next few days.

To be sure, till November this year, Delhi recorded its second-lowest average AQI in the last eight years, with only the Covid-affected year 2020 performing better.

“The average AQI of Delhi for the period January – November this year has been recorded as 187 as against 201 in 2024, 190 in 2023, 199 in 2022, 197 in 2021, 172 in 2020, 203 in 2019 and 213 in 2018 respectively, during the corresponding period,” said the Commission for Air Quality Management.

The spell of cold northwesterly winds has also impacted night-time temperature, which dropped from 10.4 degrees Celsius (°C) on Saturday to 8.3°C on Sunday, making it the season’s third lowest so far. It is forecast to dip further and may touch 7°C by December 4, data shows.

The maximum temperature fell from 26.5°C on Saturday to 24.3°C — two notches below normal.

“The minimum and maximum temperatures are likely to fall from December 4 to 5 by two to three degrees Celsius,” said an India Meteorological Department (IMD) official.