With a sharp drop in temperatures, daily wage workers and commuters in Delhi and the National Capital Region are seeking warmth by burning wood along roadsides.
But by doing so, they are adding to Delhi’s winter smog. Biomass burning is a major contributor to Delhi’s severe winter air pollution, releasing significant PM2.5 and black carbon.
The popular notion is that farm fires in neighbouring states like Punjab and Haryana are a major cause of Delhi’s winter smog. However, a recent analysis by Delhi-based think tank Centre for Science and Environment (CSE) disproves this.
The study compared the “early winter” months of October and November—a period heavily influenced by farm fires (though these were less this year)—with the “post-farm fire” period of December, when the impact of stubble burning becomes negligible.
Despite the farm-fire contribution to PM2.5 levels dropping sharply in December the average PM2.5 levels have actually increased, CSE found. 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, according to the think tank.