I got a gas mask! So I could run in AQI 200+.
https://www.amazon.com/gp/product/B07HNWRGLG/ref=p...It is a probably patriotic gas mask. It has "USA Seller". Hopefully USA is not too cheap.
When running with gas mask, turns out it is harder to get back breath if you run out of it - the volume of lungs is decreased due to the breathing space: you first get in a bit of old air, then the new good one.