Wildfires can affect air hundreds of miles away

Wildfires can cause temporary large increases in outdoor airborne particles, and substantial increases in gaseous air pollutants such as carbon monoxide, nitrogen dioxide, formaldehyde, and acetaldehyde.  Large wildfires can increase air pollution over thousands of square kilometers [or thousands of square miles].

https://iaqscience.lbl.gov/cc-wildfires#:~:text=Wildfires%20can%20cause%20temporary%20large,acetaldehyde%20%5B40%2D43%5D.