Delhi: Share of stubble fires in city’s air pollution still low, for now

Delhi: Even as Delhi continues to choke under a “very poor” air quality index for the third straight day, experts said that the city has so far been spared the usual haze of farm smoke that typically engulfs it at this time of year. The contribution of stubble burning in neighbouring Punjab and Haryana has remained negligible this season – below 1% on most days, and peaking at just 2.6% so far, according to data from the Centre’s Decision Support System (DSS).

The peak share so far, at 2.6%, was recorded on October 17, according to DSS data, meaning Delhi’s spike in pollution right now is largely down to both local and cross-boundary emissions – particularly industries and vehicles.

Typically, the impact of farm fires begins to rise sharply in the last week of October and peaks in early November. This year, however, forecasts suggest that the seasonal surge will be delayed until at least October 28, as winds continue to blow largely from the east rather than the northwest, which normally carries smoke from Punjab and Haryana into Delhi.

Experts also said that a combination of factors – particularly the devastating floods in Punjab earlier this year – has disrupted the paddy harvest cycle and slowed the onset of stubble burning. “The floods in Punjab may have impacted the harvesting pattern, which could lead to a delayed spike in farm fire counts. Normally, the peak is seen in the start of November, but so far the impact has been negligible,” said Sunil Dahiya, founder and lead analyst at the think-tank Envirocatalysts.

DSS data this week showed stubble smoke contributing just 1.62% to Delhi’s PM2.5 concentration on Wednesday, 1% on Tuesday, and 0.83% on Monday. The contrast with last year is striking: by October 22, 2024, the share of stubble smoke had already reached 8% and climbed to 27% by the end of the month.

Mukesh Khare, an air pollution expert from IIT Delhi, said that harvesting this year In Punjab has particularly been delayed. “The floods have meant the soil is still wet for a lot of farmers, who are waiting to harvest in the coming weeks. The harvest and sowing will be slightly delayed this year, so Delhi is not seeing any significant impact yet,” he said.

Farm fires are a crucial seasonal contributor to Delhi’s pollution, particularly between October and November. When northwesterly winds prevail, smoke from burning crop residue in Punjab and Haryana travels toward the capital, where calm local conditions trap pollutants near the ground. Over the years, a combination of Supreme Court directives and interventions by the Commission for Air Quality Management (CAQM) has helped reduce the overall intensity of such fires, with increased promotion of in-situ and ex-situ residue management techniques.

To be sure, fire counts are beginning to rise gradually as the harvesting window opens. Data from the Indian Agricultural Research Institute (IARI) shows that Punjab recorded 69 farm fires on Wednesday – the highest single-day count of the season so far – and 62 on Tuesday. Between September 15 and October 22, the state reported 484 farm fires, compared to 1,581 in the same period last year. Haryana recorded three farm fires on Wednesday and four on Tuesday, bringing its total since September 15 to 58, far lower than the 665 recorded during the corresponding period last year.

The Indian Meteorological Department (IMD) forecasts that winds will remain variable until October 26, oscillating between westerly and easterly, before turning predominantly easterly through October 28. DSS projections indicate that the share of stubble smoke will hover around 1.5% on Thursday and Friday, before dipping back to 1% on Saturday.

In contrast, during the same window last year, stubble burning contributed more than 15% to Delhi’s PM2.5 levels on 26 days between October 23 and November 23. On 14 of those days, the share crossed 20%, peaking at 35.18% on November 1 – day after Diwali.
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