I have lots of respiratory problems including asthma. You'll get a nebulizer (special machine with a compressor pump you plug in the wall). My medicine goes in a hand held deliverer that you can put in your mouth-the masks can make your nose tickle. Treatments take about 15 minutes. I just pop my neb on and do whatever-computer, tv, etc. Albuterol is the main med. But if your son gets really shaky, hyper, fast heartrate Xopenex is just as effective. I take Xopenex (levelalbuterol) because I'm intolerant to albuterol. The severity will depend on how often you take treatments (usually at least 2x a day). Pulmicort (another nebulized med) may also be used depending on the severity. Rescue inhalers have a mouthpiece and a small chamber that you squeeze. These should be with you at all times. They relax and open the airway in the start of an attack. Some people with severe asthma may carry Epipens and may be on other meds.
My other respiratory problems (weak muscles from Muscular Dystrophy, low vital capacity, partially collapsed lung, sleep apnea) cause me to have a trach and use a vent part time.
My main triggers are dust, chemical smells/paint, lumber, certain perfume, getting too hot, and getting mad or scared.
Disney is very accomodating. First Aid centers are a great place to take a treatment and cool off-if heat is a trigger there may be other accomodations...
I would also post this on the disABILITIES board as they always have great info for touring the World with a health problem.
Christamae