Idaho Among Least Polluted States
I'm pretty surprised to find that Idaho is on the list of least polluted states in America. Clearly these people have never driven through and smelled Jerome. Not that I think the state is gross or filthy - but when we moved here you could determine what part of town you were in based on the smells.
The website Health Grove based their information on something called PM2.5 particles. These are pollutants from vehicles, industrial facilities, and wood burning (so I guess the cow smell doesn't count). You can really see the difference on the map above or even if you have ever just driven south into Utah until Salt Lake and you can see the smog and polluted air.
That's great news for all of Idaho since the whole state is on the low side of air pollutants...assuming there isn't a wildfire nearby. The map above is interactive so you can just hover over areas to see their air quality.