Delhi and the National Capital Region (Delhi-NCR) have experienced intense, widespread smog in December than the peak stubble burning months of October and November, according to a new analysis by Delhi-based think tank Centre for Science and Environment (CSE).
“The study compares the “early winter” months of October and November—a period heavily influenced by farm fires—with the “post-farm fire” period of December, when the impact of stubble burning becomes negligible,” a statement by CSE noted.
“The persistence of pollution beyond farm fires is strongly evident in this analysis,” it added.
Anumita Roychowdhury, executive director-research and advocacy at CSE, said the findings revealed a concerning reality: Delhi’s winter pollution does not dissipate once stubble burning ends; instead, it intensifies.
“Despite the farm-fire contribution to PM2.5 levels dropping sharply in December the average PM2.5 levels have actually increased. The stark contrast between declining fire influence and rising pollution levels indicates dominance of local and regional sources—vehicles, industry, waste burning, solid fuels for domestic cooking and heating,” said Roychowdhury.
She added that while managing farm fires is important, air quality goals cannot be met without aggressive, year-round action against urban and regional emission sources for zero emissions transition.
“The smog is sustained by a combination of local emissions, regional inflows, and secondary aerosol formation, requiring coordinated airshed-level action alongside aggressive control of local sources,” Roychowdhury noted.
According to Sharanjeet Kaur, deputy programme manager, Urban Lab, CSE, the build-up of pollution was felt across various urban centres in the NCR.
“While some towns saw marginal declines, most cities recorded a sharp rise in PM2.5 levels: Noida: 38 per cent increase; Ballabhgarh: 32 per cent increase; Baghpat: 31 per cent increase and Delhi: 29 per cent increase. This regional spike is driven by local emission sources and exacerbated by stagnant winter meteorology, which prevents the dispersion of pollutants,” she said.
“Moreover, data from the Decision Support System (DSS) for December 1-15 highlights the complexity of the problem. During this period, local sources within Delhi accounted for only about 35 per cent of total PM2.5. The remaining 65 per cent originated from neighboring NCR districts and regions further away. Within Delhi’s local contribution, vehicles are the dominant primary source, accounting for nearly half of all local emissions,” said Shambhavi Shukla, programme manager, Clean Air programme at CSE.
The analysis is based on the real time data available from the current working air quality monitoring stations in Delhi-NCR. Estimate of contribution of farm stubble fire smoke to Delhi’s air quality is sourced from the Union Ministry of Earth Science’s System of Air Quality and Weather Forecasting and Research (SAFAR). Real-time source contribution and chemical composition data are taken from the Decision Support System (DSS) developed by Indian Institute of Tropical Meteorology Pune.
CSE has proposed the following key action points:
Meet ambitious electrification targets for all segments of vehicles in a time-bound manner for zero tailpipe emissions; scrap and replace older vehicles
Upscale integrated public transport with last-mile connectivity and walking and cycling infrastructure to increase ridership and active commuting
Restrain the use of personal vehicles with parking caps and pricing and congestion tax
Encourage industry to switch over to affordable cleaner fuels and stringent emissions control; lower the taxes on natural gas; electrify industrial processes
Close the waste loop to stop burning: segregate waste, remediate legacy waste and promote recycling
Force power plants to meet emission standards
Recycle construction waste, enforce dust-control; put into place smart monitoring systems for enforcement throughout the year
Ensure access to clean fuels for households for cooking and heating
Eliminate farm fires — decompose or plough straw back into the soil to increase soil carbon. Encourage bio-methanation of straw for fuel and natural gas to increase the income of farmers