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Pollution Source Mystery: Delhi Lab Faces Gaps
25 Oct
Summary
- New pollution lab struggles to identify 'secondary sources'.
- Pollution prediction model uses outdated 2021 emissions data.
- Lab's PM2.5 readings are significantly lower than official monitors.
Delhi's new Advanced Atmospheric Chemistry and Aerosol Toxicity Analysis Laboratory (Aatal) is experiencing initial difficulties in providing complete air pollution source data. The lab's measurements from October 20-24, 2026, show that particles formed through in-air chemical reactions, termed 'secondary sources,' constituted a substantial 29.3% to 42.2% of daily PM2.5 estimates, exceeding direct vehicle emissions in some instances. Officials currently lack a system to trace the origins of these secondary aerosols.
A secondary issue is the discrepancy between the lab's PM2.5 readings and those from Delhi's established monitoring stations. For example, on October 22, 2026, the lab recorded 55.3 micrograms per cubic meter (µg/m³), which was only 47% of the average reading from city monitors that day. The lab is undergoing updates to address these 'teething issues' and improve accuracy.
Adding to the complexity, the lab's air pollution prediction model, the Decision Support System (DSS), continues to use an emissions inventory from 2021, based on 2016 surveys. A replacement inventory, with a 2026 baseline, is anticipated by June 2027. This lag means the model's forecasts may not fully account for current pollution dynamics, particularly regarding secondary organic aerosols and nitrates, which were not simulated in older versions and formed a significant portion of the lab's measurements.
