When you noticed that a child feels irritate without reason for it, and seen to have some trouble breathing. open the refrigerator and stand bu it for some minutes. The cold refreshing air will help the child to calm down a little bit. Then sit down alone with hime for a moment with enough space between both. after he is stable call the parents, and let them know.
I don’t have any child under my care with asthma, but I personal suffer from it. I do that when I feel that way because my mother use to do it.