Sat Feb 15 16:30:00 UTC 2025: ## Study: Stubble Burning Not Primary Cause of Delhi-NCR Air Pollution

**New Delhi, February 15, 2025** – A new study published in *Climate and Atmospheric Science* challenges the widely held belief that stubble burning in Punjab and Haryana is the primary driver of Delhi-NCR’s severe air pollution. The research, involving multiple Indian institutions and the Research Institute for Humanity and Nature (RIHN) in Japan, reveals that stubble burning contributes only about 14% of the PM2.5 concentration in the Delhi-NCR region.

The study, based on field measurements, airmass trajectories, and model simulations, found no linear correlation between the number of stubble-burning events and PM2.5 levels in Delhi-NCR. Despite a significant decrease in stubble burning events in Punjab and Haryana – a decline of over 50% between 2015 and 2023 – PM2.5 concentrations in Delhi-NCR remained relatively stable. Data from a network of 30 sensors deployed across Punjab, Haryana, and Delhi corroborates these findings. Furthermore, the study notes that while stubble burning almost ceases after November, poor air quality persists through December to February due to factors like stagnant winds and temperature inversions.

The researchers emphasize the importance of local sources of pollution. Analysis of day-night variations in PM2.5 and carbon monoxide (CO) levels indicates a higher concentration of CO at night in Delhi-NCR, suggesting significant contributions from local sources like fossil fuel combustion and localized biomass burning. The study highlights that the day-night difference in PM2.5 is significantly smaller than that of CO in Delhi-NCR, contrasting with the pattern observed in Punjab and Haryana during peak stubble burning periods.

Dr. Poonam Mangaraj of RIHN, lead author of the study, stated that while wind patterns influence pollutant transport, other meteorological factors and local emissions significantly impact PM2.5 levels. Dr. Prabir K. Patra of RIHN further noted that PM2.5 levels remain high well beyond the stubble burning season, until the arrival of western disturbances.

Independent expert Dr. Sachchida N. Tripathi from IIT Kanpur (not involved in the study) estimated that the transport sector contributes about 30% to PM2.5 in Delhi-NCR, with local biomass burning accounting for 23%. Stubble burning, he notes, contributes only around 13%, and primarily during October and November. The study concludes that local sources, including industrial emissions, road transport, and construction activities, are far more significant contributors to Delhi’s air pollution problem than previously believed. The effectiveness of the Graded Response Action Plan (GRAP) in reducing PM2.5 levels during periods of stringent enforcement further supports this conclusion.

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