Moving slowly is the only thing that works for me. Ventolin and such don’t seem to improve my breathing out there. If possible, avoid areas where the air quality is poor for obvious reasons. I hiked the JMT this past summer, and we were about 75 miles away from some big fires toward the end. I was wheezing a bit, so slowed down even more, and that helped get me thought it.
Hope this helps - good luck.
Lisa