Delhi's Winter Smog Worsens After Farm Fires End, Reveals CSE Study

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.

This post-stubble phase has experienced intense, widespread smog across NCR -- more severe than the stubble burning period. The persistence of pollution beyond farm fires is strongly evident in the analysis.

"These findings reveal 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 Anumita Roychowdhury, Executive Director-Research and Advocacy at CSE.

"While managing farm fires is important, air quality goals cannot be met without aggressive, year-round action against urban and regional emission sources for a 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."

"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," said Sharanjeet Kaur, deputy programme manager, Urban Lab, CSE.

"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 the total PM2.5. The remaining 65 per cent originated from neighbouring 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.

This analysis is based on the real-time data available from the current working air quality monitoring stations in Delhi-NCR.

The estimate of the contribution of farm stubble fire smoke to Delhi's air quality is sourced from the 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 IITM.

- IANS