New Delhi: The Decision Support System (DSS), which provides data on the sources of local and regional PM2.5 pollutants, hasn't been updated since Nov 29. It is the city's lone source apportionment system and estimates the contribution of varied sources to the capital's air pollution.
DSS is being reviewed by an expert committee, revealed sources in the Commission for Air Quality Management, and it is expected to start operating soon after some changes are effected. However, experts said data should be updated for transparency and public awareness.
Launched in Oct 2021, and developed by the Indian Institute of Tropical Meteorology, Pune, and funded by CAQM, DSS estimates and forecasts the contribution of local sources of pollution and those in 19 NCR districts to Delhi's PM2.5. It also calculates the percentage contribution of stubble burning to the city's air pollution. The system is available only for the winter season (Oct to Feb). The last data available on the DSS website is for Nov 26-29. Last winter, DSS had briefly stopped sharing data on pollution sources in Delhi.
Sources in CAQM said DSS was still in the developmental state and hadn't been fully commissioned. "A project evaluation committee is reviewing DSS periodically because its data and accuracy were not in line with the terms of reference decided for the model. Some data used by the system or emission inventory was quite old. DSS has also been asked to update its weather forecasting techniques or methodologies," said a CAQM official.
The official added that air pollution sources and emission patterns over the years in the entire NCR, as well as the weather forecasting techniques, needed to be updated in DSS. The system is being evaluated and will be resumed after changes are introduced to improve its accuracy, said the sources.
According to DSS's website, the region and source-wise contributions are based on the emissions inventory formulated in 2021. "For a more accurate estimation of source contribution, the latest emission fields are required," says DSS's website.
An IITM official confirmed that the system was being reviewed by an expert committee. "DSS was commissioned along with the early warning system in 2018, and it was then capable of calculating the share of biomass burning in Delhi's air quality. However, after CAQM was formed, the commission in 2021 funded the project for calculating other sources impacting Delhi's air quality," said the official, who, however, offered no clarity on when this system will become operational again.
Experts emphasised that source apportionment data was needed to prepare strategies and reduce air pollution at the source level. Anumita Roychowdhury, executive director, research and advocacy, Centre for Science and Environment, said, "Dynamic forecasting of the relative contribution of pollution sources and real-time assessment of the contribution of pollution sources to the city's air quality are critical for responsive and transparent decision-making, science-based air quality management, and tracking progress. Public investments in these systems need to be upscaled and not become wasteful."
Sunil Dahiya, founder and lead analyst, Envirocatalysts, added that by withholding data, DSS risked further erosion of the already minimal transparency in identifying pollution sources. "This lack of openness undermines accountability and hampers effective action against pollution. Decision-makers must leverage available data and tools like DSS, real-time source apportionment studies, and other systems to address pollution. Failing to do so wastes public resources, scientific efforts, and critical time needed to combat pollution effectively," remarked Dahiya.