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Delhi Smog: Stubble Burning Not Sole Culprit
1 Aug
Summary
- Secondary particulate matter is a major contributor to Delhi's winter pollution.
- Transport emissions and biomass burning also significantly impact air quality.
- Farm fire incidents in Punjab and Haryana have declined significantly.
A recent study challenges the widespread view that stubble burning is the primary cause of Delhi-NCR's annual smog. The findings indicate that secondary particulate matter formed through atmospheric chemical reactions and transport emissions are larger contributors to winter pollution.
These secondary particulates account for 24-28% of PM2.5, followed by transport emissions at 19-24%. Biomass burning, encompassing crop residue, municipal waste, and domestic use, contributes 17-23%. Road dust and industrial sources also add to the pollution load.
While stubble burning exacerbates pollution during post-monsoon, winter smog is a result of multiple simultaneous sources. The biomass burning category is broader than just stubble burning alone.
Summer pollution profiles differ, with dust becoming dominant. Farm fire incidents in Punjab and Haryana have seen significant declines over the past two years, with Punjab reporting a 53.1% decrease in 2025 and Haryana a 52.9% decrease.
However, Haryana saw an 85.5% increase in farm fires during the recent rabi season. The Commission for Air Quality Management (CAQM) is promoting in-situ residue management and ex-situ utilization, mandating co-firing of biomass pellets in thermal power plants and brick kilns.
Financial support for pelletisation plants aims to utilize paddy straw, providing farmers alternatives to burning. Improving Delhi-NCR's air quality requires addressing transport emissions, industrial pollution, road dust, and construction activities alongside stubble management.
