Stubble smoke, cold winds keep Delhi covered in haze
Delhi’s 24-hour average AQI deteriorated to 322 (very poor) at 4 pm on Friday, up from a reading of 311 (very poor) at the same time on Thursday.
The impact of cold northwesterly winds continued across the capital on Friday — bringing stubble smoke from Punjab and Haryana, while also keeping mercury low. The Capital witnessed yet another morning with a thick thick haze of pollutants and shallow fog shrouding the skyline in the early hours, before sunlight improved visibility. Even then, air quality remained in the ‘very poor’ category.
Delhi’s 24-hour average AQI deteriorated to 322 (very poor) at 4 pm on Friday, up from a reading of 311 (very poor) at the same time on Thursday. The share of stubble burning in Delhi’s total PM 2.5 concentration stood at 8.68% — marginally lower than the 9.48% contribution recorded on Thursday, a season-high so far, data from the Decision Support System (DSS), under the Ministry of Earth Sciences (MoES), showed. On the ground, a faint smell of smoke lingered in the air, particularly in the early morning and late evening hours.
DSS estimates the contribution of different sources of pollution in Delhi’s air, including emissions from 19 NCR towns. It had initially forecast that the contribution of stubble burning could be as high as 38% on Friday. An actual contribution was released in the evening — based on the day’s daily fire count and meteorological conditions. DSS’s forecast shows a contribution of 30.9% is likely on Saturday.
Prior to Thursday, the highest contribution of stubble burning to Delhi’s air was 5.87% on October 28.
Past data shows stubble fires have become a serious contributor to the yearly choke in Delhi, typically peaking in the first week of November. The peak single-day contribution last year was 35.1% on November 1. It was at a peak of 35% on November 3, 2023, same as 2022 (35% on November 3). Meanwhile, it was 48% on November 6 in 2021.
Data from the Indian Agricultural Research Institute (IARI) showed Punjab recorded 100 farm fires on Friday, while the count was 18 in Haryana. This was down from 351 fires in Punjab on Thursday and 35 in Haryana.
The wind direction — predominantly northwesterly — also resulted in a chilly morning. Safdarjung, the base station for Delhi’s weather, recorded a minimum of 12.7°C on Friday for a second day— two degrees below normal and lowest so far this season. The India Meteorological Department (IMD) has forecast the minimum will remain between 10-12°C at Safdarjung, possibly dipping below 10°C on Monday.
Across all stations, the lowest minimum was 11.2°C at Lodhi Road, followed by 11.4°C at Ayanagar. The maximum meanwhile stood at 28.6°C, one degree below normal. It is likely to remain in this range.
“The dip happens usually after fresh snowfall and when northwesterly winds blow. Clear skies also add to the effect as the surface heating that occurs during the day is lost into the atmosphere at night-time,” said an IMD official, adding a gradual dip in night-time temperature will continue into the weekend.
Of the 39 active air quality stations, 29 had an AQI over 300. The remaining 13 had an AQI over 200, data showed. HT’s analysis of air quality data from the city’s 39 active ambient air quality stations on November 5 had revealed missing data, suspicious measurement patterns, and algorithmic loopholes in how the city’s average AQI is calculated. It flagged how these factors combine to produce readings which may not accurately reflect ground conditions — meaning the actual AQI could even be worse.
The AQI shot up by over 100 points on Thursday, following the intrusion of stubble smoke, firecracker emissions from Gurpurab and local emissions, leading a smoke-filled sky until wind speed picked up from 10 am onwards. Delhi recorded similar conditions, with calm winds leading to poor visibility as smog impacted the city skyline.
Experts said despite floods in Punjab this year, which saw late harvesting and subsequent stubble burning, red dots are quickly beginning to accumulate on satellite imagery. “Winds remain northwesterly and will continue to do so for the next few days. Stubble smoke will thus be an important factor,” said Mahesh Palawat, vice president at Skymet meteorology.
