If you have any doubts purchase an extra
albuterol sulfate inhaler and have him keep him with it if he
is at kindergarten or school. A single use of the inhaler (if used inappropriately) is not going to cause any life-threatening problems, and if he does develop an asthmatic attack, it will keep him alive. Get youself a good stethascope and learn how to auscultate his lung fields anterior and posterior, four quadrants. Listen for wheezes, rales and ronchi.