Delhi pollution not a city-only problem: 72% of NCR PM2.5 linked to sources beyond local emissions, study finds

Delhi's pollution is not Delhi's alone; only about 28 per cent of NCR PM2.5 is estimated to come from local sources. A new Centre for Study of Science, Technology and Policy (CSTEP) report argues that roughly one-third of pollutants come from other Indo-Gangetic Plain states, and another third from neighbouring countries. It argues that coordinated action on household fuel use, industry, transport, waste and farm burning could cut PM2.5 levels more effectively than isolated city-level measures. It claims that pollution could not be solved by individual cities acting alone; states across the region must coordinate their policies.

The study, “Beyond State Boundaries: Quantifying Interstate Air Pollution Transport and Sectoral Solutions in the Indo-Gangetic Plain”, identifies residential emissions, including the use of solid fuels for cooking and heating, as the largest local contributor, followed by industry, natural and agricultural sources, transport and open burning.

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The report says that winter air pollution is driven by a combination of emissions and meteorological conditions such as low wind speeds, shallow boundary layers and temperature inversions, which trap pollutants closer to the ground. Crop-residue burning sharply worsens post-monsoon air quality, but a 50 per cent cut in Punjab and Haryana burning delivers about a 5 per cent PM2.5 reduction in Punjab during October-November.

CSTEP argues that isolated action by one city, state or sector will produce limited gains. In its combined modelling scenario- 50 per cent cuts in residential, transport, energy, industrial and agricultural-waste-burning emissions, plus a 90 per cent reduction in waste emissions-annual PM2.5 levels fell by about 23 per cent in the NCR, from 67.9 to 52.3 µg per cubic meter. In Punjab, they fell by about 20 per cent, from 77.8 to 62.2 µg per cubic meter.

The report recommends an airshed-based approach for the wider Indo-Gangetic Plain. This would involve establishing a Commission for Air Quality Management in the National Capital Region and Adjoining Areas (CAQM), shared regional pollution-reduction targets, aligned enforcement timelines, a common approved-fuel list, coordinated policies on vehicle scrappage and electric vehicles, stronger industrial monitoring, satellite-based tracking of fires, and a high-resolution national emissions inventory.