Maybe I was just used to the smog as a kid, but I dont remember ever noticing poor air quality in the 70s and 80s - other than winter inversions. When Geneva was till operating.
I moved out in the early 90s and visit maybe once a year now.
Just visited last week. It was the first time I remember visible smog obstructing the mountains in summer time.
Maybe it was due to fires.
It'd be neat if BYU or UVU explored thorium molten salt nuclear reactors. The church should for that matter. Could be a game changer to help the 3rd world where the church is growing.