Stubble burning contributes only 14% PM2.5 in Delhi-NCR: study

• A study published in January 2025 found no linear correlation between stubble-burning events in Punjab and Haryana and PM2.5 concentration in Delhi-NCR.

• Crop residue burning in Punjab and Haryana contributes only about 14% of PM2.5, making it not a primary source of particulate matter concentration in Delhi-NCR.

• The study was published in the journal Climate and Atmospheric Science.

• The study found that PM2.5 concentration in Delhi-NCR remained stable despite the decline in stubble-burning events in Punjab and Haryana by over 50% from 2015 to 2023.

• The air quality index in Delhi-NCR has remained in the “very poor” to “severe” category since 2016 due to stagnant winds, lower mixing heights, and inversion conditions.

• The amount of biomass burned in Punjab and Haryana does not always determine the air quality of heavily urbanised Delhi-NCR.

• The study found a link between stubble burning and PM2.5 concentration in Delhi-NCR when there is strong wind.

• The day-night differences in PM2.5 are about 20% in Delhi-NCR, while the average CO concentration is about 67% greater in the night compared to the day in 2023, and about 48% in 2022.

• The higher CO emission at night in the Delhi-NCR region points to sources other than stubble burning.

• The study also found that the contributions of local industrial and other anthropogenic sources to PM2.5 in the Delhi-NCR are much greater than crop residue burning in Punjab and Haryana.