I will give you my "how Arizona was ruined shpiel." Let's see, a whole bunch of people, mostly from the midwest, some from the east, moved there and wanted to re-create their landscaping back home. Lots of lawns and non-indigenous plants. Fake lakes. Houses built so close together, the population skyrocketed, and those people brought lots of cars. No real public transportation until recently. Put them in a valley, with air inversions and lots of dust and mold spores. I bet you get the picture!
Then, there's the whole gene pool of asthmatics who moved there in the 40s and 50s who married each other and had kids with asthma! Huge population of asthmatics.
I think the constant wind and changing temperatures are good for me. The air here is clear, with the exception of very hot and humid days a few times in the summer.
I've only been to Boulder once. Other than not being able to breathe because of the altitude, I was fine...