Farm fires drive Delhi’s ‘severe’ smog as stubble share touches season high of 22%

Punjab reported 155 farm fires on Wednesday, compared to 312 on Tuesday. Haryana recorded 29 on Wednesday and 72 on Tuesday

As Delhi choked on ‘severe’ air for the second consecutive day, smoke from stubble fires in Punjab and Haryana made up nearly a quarter of the city’s PM2.5 load — the highest share this season. Data from the Centre’s Decision Support System (DSS) showed that stubble burning contributed 22.47% to Delhi’s PM2.5 on Wednesday, up from 15.45% on Tuesday and 13.68% on Monday.

A farmer burns stubble in a crop field in Punjab. (REUTERS)

Tuesday marked the Capital’s first “severe” air day this season, with northwesterly winds, which are ideal for carrying stubble smoke from Punjab and Haryana, prevailing through the day. The 24-hour average AQI stood at 428 on Tuesday and 418 on Wednesday. Forecasts by the DSS indicate a decline in the coming days, possibly due to a shift in wind direction, which turned westerly to southwesterly on Wednesday. The DSS has projected that stubble burning’s contribution will fall to 10.16% on Thursday and 8.59% on Friday.

HT had earlier reported on November 11 that the DSS — currently the only active source apportionment model identifying contributors to Delhi’s PM2.5 levels — has been inconsistent in forecasting the impact of stubble burning this season.

While the system routinely issues forecasts and later updates the “actual” daily contribution based on real fire counts, discrepancies have been frequent. On several occasions, DSS predicted over 30% contribution from farm fires, but the actual share turned out to be less than 10%.

“Winds were northwesterly till Tuesday but switched to westerly and even southwesterly on Wednesday,” said Mahesh Palawat, vice-president (meteorology and climate change) at Skymet. “Predominantly, wind direction is expected to hover between westerly and northwesterly, with speeds likely to pick up marginally on Thursday and Friday.”

Although farm fire numbers remain lower than in previous years, they have shown a sharp uptick in recent days. Punjab reported 155 farm fires on Wednesday, compared to 312 on Tuesday. Haryana recorded 29 on Wednesday and 72 on Tuesday.

According to data from the Indian Agricultural Research Institute (IARI) till November 12, Punjab has recorded 4,662 farm fires so far this year, compared to 7,112 in the same period last year. Haryana has reported 464 cases this year, down from 1,020 last year.

The peak single-day contribution from stubble burning last year was 35.1% on November 1. It was 35% on November 3 in both 2022 and 2023, while in 2021 it peaked at 48% on November 6.

The DSS estimates the contribution of multiple pollution sources — including transport, industry, biomass burning, and emissions from 19 NCR towns — to Delhi’s PM2.5 levels.

V.K. Sehgal, principal scientist at IARI’s Consortium for Research on Agroecosystem Monitoring and Modelling from Space (CREAMS), said that while isolated spikes in fire counts may still occur, the overall numbers are expected to remain below previous years. “Harvesting was delayed this season, but a significant portion of the crop has already been cleared,” he said.

Tuesday was the capital’s first ‘severe’ air day, with wind direction northwesterly – which is ideal for transporting stubble smoke from Punjab and Haryana to Delhi. The 24-hour average AQI stood at 428 on Tuesday, while it was 418 on Wednesday. Forecasts by DSS show a dip ahead, possibly due to a change in wind direction, which was westerly to southwesterly on Wednesday.

DSS has forecast a contribution of 10.16% on Thursday and 8.59% on Friday.

HT had on November 11 reported how the DSS – the only source apportionment study presently available to identify sources contributing to Delhi’s PM 2.5, was failing to accurately forecast the impact of stubble burning in Delhi this season. DSS issues both a forecast for the upcoming days, later releasing the ‘actual’ contribution of farm fires on that day.

It said on multiple days, while the forecast showed a contribution of over 30% was likely in Delhi, however, the actual contribution, based on the day’s actual fire count, turned out to be much lower -- less than 10% on all days.

“Winds were northwesterly till Tuesday, but switched to westerly and even southwesterly on Wednesday,” said Mahesh Palawat, vice president at Skymet. Predominantly, the wind direction is expected to hover between westerly and northwesterly. “We may see wind speeds pick up marginally on Thursday and Friday,” he added.

Though much lower in comparison to previous years, farm fires are on the rise in the past few days. Punjab recorded 155 fires on Wednesday, while it was 312 on Tuesday. In Haryana, the count was 29 on Wednesday and 72 on Tuesday.

Data from the Indian Agricultural Research Institute (IARI) till November 12 shows Punjab has recorded 4,662 fires this year, in comparison to 7,112 fires in the same period last year. In Haryana, the count stands at 464 fires so far, in comparison to 1,020 in the same period last year.

he 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.

DSS calculates the estimated contribution of sources of pollution to Delhi’s PM 2.5 levels, including emissions from 19 NCR towns.

VK Sehgal, principal scientist at IARI’s Consortium for Research on Agroecosystem Monitoring and Modelling from Space (Creams), said while a few spikes may still be recorded in the daily farm counts in recent days, the numbers should be lower than previous years. “Though harvesting has happened late, but we have also seen a significant chunk harvested so far,” he added.