What's happened to the air?

This morning, as I was going in to Mesa Verde NP, the Mancos Valley was filled with haze and the Montezuma Valley, looking west toward the Sleeping Ute, wasn't much better. It's been hazy for months! Rarely is there a fairly clear day, and it's never like it used to be. I've noticed in the last year or so, taking pictures of the Four Corners area, that the vistas and long views are NEVER clear, not like they were only a few years ago. We saw haze all the way down to Tucson and back, too.

Have we reached some sort of tipping point at which the air will just never get clearer again? tv