I have lived in the desert of AZ most of my life, 25 out of 30 years. My parents were asked to move me out here as an infant with severe asthma, saying it would be better for me. It was better for me in the beginning, even though I still had very bad asthma, my attacks were fewer in number.
In the last 8-10 years however, I have had some of the worst asthma and allergy related illnesses of my life. Last fall I was sick for an entire month, on heavy doses of steroids for over two months. The air here is awful due to heavy construction and more pollution. The population and growth is out of control, so there is more smog, and lots more dust due to construction. There is typially a brown/gray cloud over the metro and even outskirts of the phoenix and outlying areas.
I am now moving back to the midwest suburbs to get into less dry air, and much less polluted air. Good luck if you come to the Phoenix area is all I have to say. — Kristen

I can only second Kristen’s comment. I live in central Phoenix and have had progressively worse allergies each year, now settled in bronchiae. It may be helpful to allergy sufferers thinking of coming to know that Phoenix is in a valley and is extremely dusty, also that whatever gets in the air (construction dust, et al.) in a valley does not leave of its own accord. It’s my feeling (unconfirmed) that a dry dusty climate provokes allergic symptoms over time — there is grit in the air and you’re breathing it in. My own thoughts: look for a moderate climate, while trying to avoid extreme humidity. Where is this place?
I just moved to Phoenix from Atlanta, GA and thought my allergies would be WAY more manageable here – I thought wrong! I’ve been trying to figure out what I’m so allergic to here since less trees/grass grow, and it has to be the dust – especially at with the overpopulation and the high construction rates – your posts confirm what I’ve suspected was true. Plus, this dry air after growing up in extreme humidity is CRAZY – I’m tired a lot and having to constantly consume water to keep my throat from feeling crazy dry. So far I’m really not a fan of Phoenix weather – of course I couldn’t have picked a worse time to move – right at the start of summer. Oh well, here goes nothing….