What's polluting Delhi the most? Stubble burning isn’t the sole cause, data reveals more offenders

Delhi has emerged as the most polluted state and Union territory in India, as toxic air has turned the national capital into a gas chamber. The national capital registered an annual population-weighted PM2.5 level of 101 micrograms per cubic meter (µg/m 3 ), nearly 2.5 times higher than the national ambient air quality standard of the nation and 20 times higher than the recommended level of the World Health Organisation (WHO), based on a new satellite-based assessment data released by the Centre for Research on Energy and Clean Air (CREA).

Based on the Central Pollution Control Board (CPCB) data, the AQI of Delhi jumped from 130 on October 1 to a staggering 428 by November 11, before falling to 327 on November 26 in the 'Very Poor' category.

Who is polluting Delhi most?

Stubble burning in Punjab and Haryana is frequently blamed for the air pollution in Delhi, but data from the Decision Support System (DSS) under the Ministry of Earth Sciences indicates more. Stubble burning contributed very little to Delhi's air pollution in early October. But its contribution rose to 2.62 per cent, coinciding with AQI crossing 250 by October 17, and later the situation worsened in November.

On 12 November, farm fires accounted for 22.47 per cent of the air pollution of Delhi, pushing the AQI to 418 (Severe). Between 18 and 20 November, their share dipped to 5.4 per cent–2.8 per cent, yet the AQI remained above 325. This shows stubble burning spikes pollution on smog-heavy days, but it is not the only driver.

Meanwhile, DSS data also indicates several other major sources are polluting the air quality of Delhi. Neighbouring cities such as Gautam Buddha Nagar, Gurugram, Meerut, Karnal, and others collectively add 29.5 per cent to Delhi’s foul air, followed by transport at 19.7 per cent.

Residential pollution (4.8 per cent), nearby industries (3.7 per cent) and construction dust (2.9 per cent) further worsen air quality. Most concerning, however, is the 34.8 per cent share from unidentified sources, making effective pollution control nearly impossible without clear attribution.