I grew up in LA and the Valley, so yeah, I know the weird
fauna and flora. Most of those plants were imported, since not much grows there naturally, but it is odd it would cause you allergies. I'm voting on the dust, personally -- I had allergies all my life, but a lot had to do with smog and my parents' smoking. My brother had asthma. What I don't understand is you say it's humid -- now that's odd! I'm so jealous -- stuck here on the East Coast.