Another thing to consider is reducing or eliminating dairy from your diet. This was suggested to me by a new doctor I started to see after moving.
I was diagnosed with asthma around 8 years old and have dealt with it my entire life. I was taking a twice daily medication to keep it under control (advair 250 diskus). It was my first summer bike commuting, and I live in the Dallas/Ft Worth area. After the entire summer of riding, I still couldn't "open my lungs" for a good hard ride. At the time I wanted to conduct a full allergy test with the doctor to determine if that were the cause. She said, "let's start with diet." I proceeded to tell her my typical diet to which she replied, "let's start cutting out the dairy products and see what happens."
About a week later I stopped eating dairy (after consuming what was in my fridge in my typical routine). 3 days later I had the best commute (up to that point anyway) ever. It was a "free and clear" lungs ride. I avoid dairy at every opportunity now and no longer take advair. I have had one 'attack' in the past year, but I always ride with an albuterol (sp?) inhaler so it was a non-issue.
I'm not suggesting this will work for everyone, but it worked for me. Dairy increases mucous production, which in turn affected my asthma significantly. It is life-changing to eliminate dairy as it is in everything, but bike commuting is pretty life-changing also.
Lastly, this is my first post on the board. I've been lurking for almost two years now (I typically don't have anything to add to posts). I felt my experience might benefit someone here.
~Raybies
p.s. I'm currently a 'driver' as I broke my foot in a freak bounce-house accident with my 20month old a couple weeks ago. This blows. I don't know how I drove for so long. heh