Farm fires subside but Delhi still choked, says CSE report

The study underlined that Delhi’s pollution is sustained by a combination of local emissions, regional inflows, and secondary aerosol formation. It cited data from the IITM’s Decision Support System that revealed that local sources within Delhi accounted for about 35 per cent of total PM2.5 in early December, with vehicles alone contributing nearly half. Industry, household fuels, construction dust, and waste burning added smaller, but persistent loads. The remaining 65 per cent was transported from NCR towns and beyond, underscoring the regional nature of the crisis.

Another key highlight is with respect to the secondary particles formation through chemical reactions of precursor gases such as NOx, SO₂, and VOCs, which made up nearly two-thirds of PM2.5, with aged aerosols carried into Delhi from the wider airshed. These invisible pollutants are finer, more toxic, and more persistent, penetrating deeper into the lungs and worsening public health risks.

The regional escalation was evident across NCR cities, where PM2.5 levels rose sharply in December despite the decline in farm fires, the study noted, as it said Noida recorded a 38 per cent increase, Ballabhgarh 32 per cent, Baghpat 31 per cent, and Delhi 29 per cent. It noted that local sources as well as transboundary pollution from vehicles, industries, power plants, waste burning, and household fuels have been the hidden drivers, sustaining pollution long after the farm fires stopped.

The think tank has called for a comprehensive clean air strategy that goes beyond episodic farm fire management. Its recommendations include ambitious electrification of all vehicle segments, scrappage of older vehicles, expansion of public transport with last-mile connectivity, and measures to restrain personal vehicle use through parking caps, pricing, and congestion taxes. Industries must switch to cleaner fuels and electrify processes, while power plants must meet stringent emission standards.

Waste burning must be eliminated through segregation, recycling, and remediation of legacy waste, and construction dust controlled through recycling and smart monitoring. Households need access to clean fuels for cooking and heating, while farmers must be supported to eliminate stubble burning through straw decomposition and bio-methanation. Only coordinated, year-round, airshed-level action targeting both primary emissions and precursor gases can deliver sustained improvements in Delhi’s air quality, it noted.