Chicago and Detroit have the worst air quality in the world due to Canadian wildfires

 https://www.usatoday.com/story/news/nation/2023/06/27/chicago-midwest-hit-by-canada-wildfire-smoke/70360124007/

Air quality so bad that it's dangerous.

https://www.fox2detroit.com/news/detroit-air-quality-ranks-2nd-worst-in-world-how-to-protect-yourself

https://thedigitallabyrinth.blogspot.com/search?q=Chicago