Overview
- Central Pollution Control Board data show December’s PM2.5 averaged about 211 µg/m³, with citywide daily levels topping 250 µg/m³ on roughly a third of days and a peak of 392 µg/m³ on December 14.
- Delhi began 2026 with AQI readings around 372–382 under dense fog, with the IMD forecasting light rain and airlines cautioning of possible flight disruptions due to low visibility.
- The 2025 annual PM2.5 average fell slightly to roughly 95–96 µg/m³, a low since 2020 that experts attribute mainly to an unusually wet monsoon rather than sustained emission cuts.
- CSE and IITM’s Decision Support System estimate only about 35% of early‑December PM2.5 came from within Delhi, with vehicles the largest local source and the majority transported from the wider NCR airshed.
- Analyses report that nearly two‑thirds of winter PM2.5 was formed secondarily from precursor gases, while CREA ranks Delhi the most polluted megacity of 2025 and flags NCR‑wide breaches of standards alongside patchy monitoring coverage.