The Capital has its first breakdown of air pollution by source in nearly three years. But the Indian Institute of Tropical Meteorology ’s (IITM) new measurements cannot yet say where a large share of the pollution they measure comes from, and its air pollution prediction model still runs on a 2021 emissions estimate that its own website says needs updating, with a replacement expected only by June next year.
A senior government official said the lab’s data would add to the DSS, but the overall assessment would not become fully accurate until the inventory is updated, which officials expect to happen next year. A second problem was that the lab’s total PM2.5 reading was itself far below what Delhi ’s monitors recorded. For instance, it was 55.3 micrograms per cubic metre (µg/m³) on October 22. That number was 47% of a middle reading of 117.1 µg/m³ among 37 stations that day, a comparison with Central Pollution Control Board (CPCB) air quality data from that day showed. Delhi’s previous source studies, by IIT Kanpur in 2016 and The Energy and Resources Institute in 2018, are dated.
When this was pointed out by HT, officials said the site was still new and facing teething issues. “The PM 2.5 data will reflect accurately, shortly,” an official said. “This facility will help us understand the composition of pollution as well as the contribution of different sources,” said Union minister of state for science and technology Jitendra Singh, while inaugurating the lab, called the Advanced Atmospheric Chemistry and Aerosol Toxicity Analysis Laboratory (Aatal) at New Rajendra Nagar, on Saturday. He added that this was important for “ensuring that action is based on scientific evidence”. The model’s 2021 emissions inventory, its estimate of what each source releases, was “compiled using surveys done in 2016”, according to a 2024 paper by IITM scientists, and a replacement with a 2026 baseline is due only by June 2027. The new page calls the split “real-time” but gives one figure a day per category, with no hourly data or method. IITM’s older Analysis page shows the lab’s daily figures in a chart marked “Experimental Mode – Preliminary results” and labelled a source contribution of “NR-PM2.5”, a term the site does not explain, where the new page says “Total PM2.5 (sum of the listed sources)”. The Delhi government stopped a Washington University study in 2021 over “unsatisfactory” results and halted IIT Kanpur’s real-time study in November 2023, again dissatisfied with its methods and results.
