Delhi-NCR declared severe air pollution emergency, triggering strict measures as AQI hit 401.

Delhi-NCR activated Stage III of the Graded Response Action Plan on December 13, 2025, after air quality plunged into the "severe" category with the AQI reaching 401 due to high PM 2.5 levels. Stagnant winds and unfavorable weather trapped pollutants, prompting bans on construction, demolition, older vehicles, and diesel generators, along with school closures for classes up to five and hybrid work arrangements. The crisis, driven by winter conditions, vehicle emissions, and regional pollution sources, led to hazardous air quality across multiple cities, with some areas exceeding AQI 430.