Vehicles and combustion sources, not episodic farm fires, behind Delhi’s toxic cocktail: CSE experts

Local pollution sources, and not the smoke from stubble burning, are the leading contributors to the national capital’s foul air quality this winter season, according to a report published by Centre for Science and Environment (CSE), a Delhi-based Climate think tank, on Monday.

The study examined pollution trends in Delhi and its neighbouring areas during the early winter months spanning from October 1 to November 15.

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“Delhi-NCR cannot hide behind the smokescreen of farm fires any more. While farm fires have contributed much less to local air quality this winter, the state of the air we breathe has been ranging from ‘very poor’ to ‘severe’ – this exposes the huge impact that local sources are having,” the report stated.

The study highlighted that while all eyes in Delhi-NCR are fixed on the daily peaks of PM2.5 during early winter, the

parallel trends in toxic and extremely harmful gases, namely, nitrogen dioxide (NO2) and carbon monoxide (CO), both emitted predominantly from the tailpipe of vehicles, often go unnoticed.

Drawing attention to the tandem surges and falls in PM 2.5 and NO2 levels in the city during the morning (7-10 am) and evening (6-9 pm) hours, experts pointed out clear patterns that daily particulate pollution spikes are closely reinforced by traffic-related emissions of both NO2 and CO, especially under low-dispersion winter conditions. “Yet, every winter, pollution control efforts are dominated by dust control measures with feeble action on vehicles, industry, waste and solid fuel burning,” said Anumita Roychowdhury, executive director-research and advocacy, CSE.

According to the government data, in 2025, for most of the early winter, the contribution of farm fires to daily pollution levels has remained below 5 per cent, reaching a peak of nearly 22 per cent only for two days on November 12 and 13. The dip in fires has prevented extreme spikes, but it did nothing to clean the daily average air quality, the study noted.

Experts say while both average and peak PM2.5 levels this early winter are lower than in the past three years, the long-term trend offers little comfort. Delhi’s air-quality gains, which began around 2018 and improved through the Covid years, have now stalled, they noted.

This season’s reduced peaks are largely the result of fewer farm fires, but overall pollution remains firmly in the “dangerous” range. The October–November PM2.5 average is around 9% lower than last year, and even the worst spikes have softened slightly.

However, when compared against a three-year early-winter baseline, the average PM2.5 concentration shows no improvement at all. “It has plateaued at the same unhealthy level. Winter looks better only when compared to last year’s extreme; in real terms, pollution remains consistently high,” said Sharanjeet Kaur, deputy programme manager, Urban Lab, Clean Air unit, CSE.

Highlighting these worrying trends, experts at CSE urged the city to adopt a “leapfrog” strategy across key pollution-related sectors. Their recommendations included setting ambitious, time-bound electrification targets for all vehicle segments to achieve zero tailpipe emissions; phasing out and replacing older vehicles; and expanding integrated public transport with reliable last-mile connectivity.

They also called for stronger measures to curb dependence on private vehicles, such as parking caps, rationalised parking prices, and congestion taxes. On waste, the experts stressed the need to close the loop by ensuring segregation at source, remediating legacy dumps, stopping open burning, and promoting recycling. Ensuring universal access to clean household fuels for cooking and heating remains critical, they added.