New Delhi: Decision Support System, which estimates and forecasts the contribution of local sources of pollution and those in 19 NCR districts to Delhi’s PM2.5, resumed sharing data on Monday. However, Commission for Air Quality Management in NCR and Adjoining Areas (CAQM) said that since the emission inventory used by DSS to estimate the contribution of different sources was old, the commission was currently not using DSS’s data for pollution-related decision-making.
TOI reported on Dec 4 that DSS was not being updated from Nov 29 and the system was being reviewed by an expert committee. Launched in Oct 2021 and developed by Indian Institute of Tropical Meteorology (IITM), Pune, and funded by CAQM, DSS is the city’s lone source apportionment system and estimates the contribution of varied sources daily to the capital’s air pollution. 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).
A CAQM official said, “The regional and source-wise contributions are based on the emissions inventory formulated a few years back. For more accurate estimation of source contribution, the latest emission fields are required and refinements are still underway for DSS to be fully commissioned. IITM is working on updating the air pollution sources and data of emission patterns.”
Adding that CAQM was actively coordinating with IITM, the official said, “As and when IITM gets to a stage of final development, CAQM will start using the same for informed decision-making and further managerial actions.”
According to DSS’s website, the region and source-wise contributions are based on the emissions inventory formulated in 2021.
An IITM official said that the data was not updated for the past few days due to a technical glitch, which had been fixed. “We ran the model on Sunday. However, the system is currently being run on an experimental basis. An expert committee is evaluating DSS.” The official added that the suggestions made by the committee on completion of evaluation would be incorporated in the system.
Sunil Dahiya, founder and lead analyst at Envirocatalysts, said, “The static emission inventories have limitations and if not updated regularly, they result in an increasing share of unaccounted emission sources depicted in a high share of ‘others’ in the existing DSS forecasts, which necessitates the need for dynamic emission inventories.” Dahiya further added that the existing inventory was also based on stubble burning instances rather than accounting for burnt area, so the methodology also needed to be updated for directed actions.
“While we need dynamic inventories, the existing inventory can be used for limited directed actions on already existing sources of pollution, coupling it with continuous emission monitoring systems data (installed by industries for pollution emission monitoring) and meteorology parameters for efficient regulation by the regulator,” said Dahiya.
DSS estimated that on Monday, among the local sources, Delhi transport’s sector was the major source at nearly 12.4%, followed by Delhi and peripheral industries at 6.7%. However, the emissions from Ghaziabad and Baghpat contributed nearly 13.5% and 9.9%, respectively, to Delhi’s PM2.5.
