6 min readOct 8, 2026 05:59 PM IST First published on: Oct 8, 2026 at 05:59 PM ISTThe country has been witnessing rapidly evolving dynamics on multiple fronts in recent weeks. While much of the public discourse has been dominated by Election Commission-related developments, it was particularly gratifying to hear a minister in Delhi make a scientifically important observation: “PM₁₀ does not travel as far as PM₂.₅, so the construction contributes far less to pollution than vehicular emissions.” This is the kind of scientific understanding I have long wished to hear from policymakers and authorities. Nearly a decade ago, while presenting the SAFAR (System of Air Quality and Weather Forecasting and Research, India’s first air-quality forecasting framework) findings under the MoES, I reported that the transport sector was a major contributor to Delhi’s toxic pollution, accounting for around 40 per cent of PM₂.₅ emissions. At the time, the finding was uncomfortable. It provoked strong resistance, even a backlash. Although it was clear that PM2.5 was the most harmful to our health, we continued to devote disproportionate attention and resources to the second- or third-tier contributors, especially dust, because the National Clean Air Programme (NCAP)’s metric gauges funding, assessing performance and mitigation progress by percentage reduction in PM₁₀, where dust is a major contributor. This inevitably shaped pollution-control priorities. It is encouraging to see scientific understanding of Delhi’s pollution sources gradually finding greater acceptance in policy discourse, though the road ahead remains long.While Delhi begins work on its Winter Action Plan — narrow road-sweeping machines, doubling parking charges, work-from-home provisions under GRAP — nature may have a plan of its own. One of the biggest factors to shape Delhi’s winter air quality will be “Super El Niño,” an exceptionally strong event of the century. It has already influenced India’s monsoon, which ended with a 13 per cent rainfall deficit, the highest in a decade. Delhi defied the national trend, recording a 17 per cent surplus. This raises a question: If ENSO’s larger dynamics originate from the Pacific Ocean, why should it matter for Delhi’s winter air quality, a regional phenomenon? While a super El Niño does not generate an air pollution source, it can act as a villain by “weather trapping” in several ways. First, it can drastically reduce wind speed over North India, as a recent study by this author at the National Institute of Advanced Studies (NIAS) found. This prevents dispersion of fine particulates — PM2.5 emitted from stubble burning, vehicular transport, biofuel, and open waste burning — thereby compounding emissions for a prolonged period and leading to repeated extreme pollution episodes. Two, in all probability, westerly disturbances (WD) will be almost absent as El Niño becomes severe. The WDs bring rain in Delhi to wash away pollutants intermittently. The dry spell means prolonged accumulation of pollution without a break. Third, under the influence of this super event, winter is likely to be milder in northern India. A combination of milder daytime temperatures and nighttime cooling under stagnant conditions may lower the surface inversion layer. This can restrict vertical mixing and prevent pollutants from dispersing, causing them to accumulate in a shallow layer near the ground. As a result, pollutant concentrations can rise sharply.AdvertisementAlso Read | ‘What caused the suicide?’: A question that masks the truthPlaces in Punjab and Haryana experienced severe recent rainfall deficits, reaching as high as 23-40 per cent. Some early monsoon rains, however, enabled early paddy sowing — meaning harvesting could begin as early as the first week of October. Recent research, reinforced by conversations with farmers during a recent visit to Amritsar, suggests that stubble burning has indeed shifted from morning to evening. MODIS-based fire detection, which authorities rely on heavily, may miss a significant share of these fires. We should not repeat last year’s blind spot — when undercounting fires risked undermining the very purpose of mitigation. However, how the rainfall deficit affected the rice crop and, consequently, stubble burning, remains to be seen.The festive season when firecrackers are used arrives in the first week of November this year, when winter conditions are already firmly established, and stubble burning is expected to be at its peak. Without suitable alternatives, farmers may resort to the fastest matchbox methodology. Historically, November 5-10 has been Delhi’s most challenging pollution period in the last decade. The pattern is likely to return with greater intensity this year, as El Niño-driven weaker-than-usual winds may create a perfect atmospheric trap, allowing emissions from multiple sources to accumulate rapidly over the region. But there is an opportunity: Curbing additional emission sources at least during this critical window could spare Delhi the worst of the pollution.India’s air-quality challenge, particularly across the Indo-Gangetic Region and Delhi, is becoming increasingly complex as climate change amplifies natural drivers of pollution. It is a double whammy: Worsening emissions compounded by extreme weather events and a changing climate. This calls for science-based simultaneous action across the short, medium and long term, and not just the short term. The first and most difficult step is to move decisively from a city-centric to an airshed-based approach. The pathway is outlined in a monograph, NARFI (National Air Quality Resource Framework of India), a project developed by NIAS under the auspices of the Office of the Principal Scientific Adviser to the Government of India. Where the full airshed is too vast for practical implementation, a satellite airshed could provide an operational alternative. What is needed now is not another incremental measure, but a firm commitment to airshed-based, science-driven air-quality management.AdvertisementThe writer is chair professor, National Institute of Advanced Studies, IISc-campus, and founder project director, SAFAR