The Air Quality Index in my town is currently 260 (very unhealthy) due to a surge in wildfires in western Canada and the northwest US. There are additional smaller fires not shown on this map at this zoom level.
From the interactive map it looks like the worst air in the world right now.
I’ve experienced 450 in Chiang Mai, Thailand and you could taste the air. It was not pleasant at all.
Saw 600 in Shanghai a few years ago. It was horrific. Fortunately the Chinese government has made quite a bit of progress in improving air quality in the last decade so such terrible pollution isn’t nearly as common today as it used to be.
In the 2019 mega-fires, Sydney hit a max of over 2,500.
It can get a lot worse yet…
Yeah I was pretty impressed by how awful the air was in Beijing some years ago. Glad to hear it’s getting better.