When wildfire smoke was blowing into the US from Canada, you could feel your eyes stinging in seconds at like 250 AQI, and at 400 you could see/smell/taste/feel the smog even inside of buildings. It was supposedly like smoking a pack of cigarettes a day.
999 means move. There’s no convenience that a city offers that is worth years and years of your life, and a lower quality of life during the many fewer years you do have. I’d opt for subsistence farming without electricity in the most remote village over living in pollution that bad.
The air quality in Delhi is usually around 150-250. (Quite horrible as it is)
This huge spike in AQI is caused by unregulated stubble burning in the neighbouring states. Farmers harvest rice and burn the leftovers so that they can hurry up and plant the next crop.
Makes sense, I’d never even heard of AQI hitting 999 before; it would be crazy if it were a more consistent thing there. Still crazy to think about ~200 being the norm when you’re not even supposed to walk outside at that level, according to WHO an CDC. It’s apparently as low as 100-150 that exercise becomes bad for you rather than improving fitness based just on how much more air you have to breathe.