Delhi Government's Real-Time Source Apportionment Study Resumes, Unveiling PM2.5 Pollution Origins

The real-time source apportionment study initiated by the Delhi government is now operational, providing up-to-the-minute insights into the origins of PM2.5 pollution affecting the capital. This crucial data is now accessible on the R-asmaan portal (raasman.com), marking a significant development following a week since the Supreme Court mandated the resumption of the apportionment study, which had been inactive for about a month.

Data collected until 4 pm on Wednesday reveals that vehicles emerged as the primary contributor to PM2.5 in Delhi, accounting for 34% of pollutants. Secondary inorganic aerosols, generated from combustion sources, contributed 32%, while biomass burning contributed around 26%, according to the available data.

On November 14 and 13, vehicles remained the dominant contributor, constituting 45% and 44%, respectively. Biomass burning contributed 15% on November 14 and 14% on November 13, while secondary aerosols contributed 31% on November 14 and 14% on November 13. An intriguing observation was the high contribution of soil and road dust at 15% on November 13, dropping to just 2% on both November 14 and 15.

The apportionment study evaluates nine sources of PM2.5 particulates, including secondary inorganic aerosols, road dust, vehicles, industries, construction, biomass burning, coal and fly ash, waste burning, and residential pollution. Unidentified sources are categorized as "others."

This study offers real-time data based on the chemical composition of the air, collected using filters and assessed by a software model.

The Delhi cabinet sanctioned the real-time source apportionment project in July 2021, with an MoU signed in October 2021 between the Delhi Pollution Control Committee (DPCC) and IIT Kanpur, the project executor. Real-time data became available to the Delhi government in November 2022 and to the public from January 30, 2023.

The recent resumption of the project followed allegations by Delhi Environment Minister Gopal Rai that it had been arbitrarily halted. The Supreme Court intervened on November 7, summoning DPCC chairman Ashwani Kumar and urging the swift resumption of both the apportionment study and the anti-smog tower at Connaught Place.

A senior DPCC official confirmed the operationalization of the apportionment study site at Rouse Avenue, providing real-time data on the website from the last few days. The pending amount of ₹2 crore owed to IIT Kanpur has been cleared, ensuring the lab's full functionality.

While the website currently lacks a three-day forecast on the expected contribution of sources, the apportionment study differs from the Decision Support System (DSS), providing estimate-based models under the Union Ministry of Earth Sciences. The study employs a receptor-based model, examining the chemical breakdown of PM2.5, offering real-time insights into pollution sources for informed policy decisions.