A dense layer of smog blanketed the national capital on Monday morning, with the air quality remaining in the ‘very poor’ category, according to the Central Pollution Control Board (CPCB) while the mercury dipped further to a season low of 10.4°C, four degrees below normal.
Delhi’s 24-hour rolling average air quality index (AQI) stood at 344 at 9am. It was at a season-high of 391 (very poor) at 8am on Sunday. It remained 391 till 10am on Sunday, but began to improve soon after winds of up to 15 km/hr were recorded during the day.
Noting the air quality, the Commission for Air Quality Management (CAQM) had also called a review meeting to assess the situation at 4pm, but decided not to invoke Stage-3 measures of the Graded Response Action Plan (Grap) across NCR — citing a declining trend in the 24 hour average and no forecasts of ‘severe’ air ahead. It said stages 1 and 2 will continue to remain in place.
Sunday’s AQI also eclipsed this season’s peak of 388 at 10am on November 2, even as CAQM continued to not invoke Stage-3 measures at 350. Last December, the Supreme Court in its order of December had asked CAQM to invoke stage 3 measures at an AQI of 350 or higher for stricter pollution control rules to be invoked under Grap, with stage 4 to be invoked at 400, instead of its original threshold of 450.
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Experts attributed the improvement during the day to wind speeds picking up, with the share of stubble burning also reducing marginally as the wind direction fluctuated to westerly and southwesterly, as compared to northwesterly on Saturday.
The capital has not officially recorded a ‘severe’ air day so far this year. The last such reading was on December 23, 2024, when the AQI was recorded at 406.
In a statement, the CAQM sub-committee on Grap had noted that the AQI had dipped from 391 at 10am to 365 at 5pm.
“Given that Delhi’s daily average AQI has since shown a consistent declining trend….with the dynamic model and forecasts for weather and AQI by IMD and IITM also indicating the overall AQI of Delhi to stay in ‘Very Poor’ category in the coming days, the sub-committee on Grap opined that invocation of Stage-3 of Grap is not required at the moment and ongoing measures under Stages 1 & 2 of the extant schedule of GRAP to continue in the NCR..” it said, adding the sub-committee was “keeping a close watch on the situation” and will review the air quality scenario of Delhi-NCR accordingly.
Mahesh Palawat, vice president at Skymet said winds were becoming calm overnight, with temperatures dipping. However, strong winds are being seen during the day on Sunday — aiding dispersion. “In comparison to Saturday, where the wind direction was northwesterly, thus bringing more smoke from Punjab and Haryana, it was southwesterly to westerly on Sunday, meaning it was coming from Rajasthan and south Haryana. Thus, possibly the impact of farm fires was lower,” Palawat said, stating accumulation was seen till Sunday morning but winds of 14-15 km/hr were then recorded on Sunday post noon. “Saturday also had a slightly higher moisture content, which can again negatively impact pollution,” he added.
Prior to Monday, the lowest minimum was 11°C on November 8.
Data from the Decision Support System (DSS), which estimates the contribution of sources to Delhi’s PM 2.5 — said the contribution of stubble burning was 5.38% on Sunday, down from a contribution of 8.64% on Saturday. It has not forecast any stubble contribution for Monday.
Meanwhile, forecasts by the Centre’s Air Quality Early Warning System (EWS) for Delhi said ‘severe’ air is unlikely in recent days.
“Delhi’s air quality is very likely to be in the ‘very poor’ category from November 10 till November 12,” said the daily bulletin, adding the forecast for the subsequent six days also shows ‘very poor’ AQI.
An AQI of 51 to 100 is classified as “satisfactory”, and between 101 and 200 is classified as “moderate”, between 201 and 300 is “poor”, between 301 and 400 is “very poor”, and over 400 is “severe”, according to CPCB.