Extremely dangerous. Official Indian AQI caps at 500 (Severe). Readings of 2500 are from the US scale during Diwali fireworks spikes, driven by PM2.5 levels often exceeding 500–1000+ µg/m³.
At that intensity, even brief outdoor exposure risks acute respiratory distress, eye/throat irritation, and cardiovascular strain for everyone. Sensitive groups (kids, elderly, asthmatics) face higher immediate harm.
Stay indoors with windows closed, run air purifiers if available, and use an N95 only if you must go out. Current official city averages are lower (around 360–440) but still very poor to severe.