I just came back from the Grand Canyon, and it's awesome.
However, my friend and I did notice something - it seems that there's some kind of haze in the far horizon that seems worse as the sun rises to noon.
One interesting bit is that a polarizer can clean it up when we take photos, so that suggests it's reflected light.
Regardless, I'm curious, is that just pollution blown into the area? or some other atmospheric feature that I didn't know about