Overview
- Central Pollution Control Board data show December’s citywide PM2.5 averaged about 211 µg/m³, with daily averages above 250 µg/m³ on roughly a third of days and above 150 µg/m³ for more than 80%.
- The worst day was December 14, when the daily average hit about 392.6 µg/m³ and stations such as Mundka peaked near 597.7 µg/m³, with multiple sites exceeding nine times the national 24‑hour standard.
- CSE and IITM/DSS assessments report negligible stubble-burning influence during the peak; local sources made up roughly 35% in early December, with vehicles nearly half of the local share and secondary particles dominating.
- CREA ranks Delhi the most polluted Indian megacity in 2025 at roughly 96 µg/m³ annually, notes most NCR cities with adequate data breached PM2.5 limits, and flags monitoring gaps with only 14 of 29 cities meeting data coverage thresholds.
- Stage 3 GRAP restrictions remain in place as air quality stayed in the very poor range around 377–382 on New Year’s Day, with dense fog, the coldest day since 2019, and a light rain forecast prompting visibility warnings and airline advisories.