It is our hypothesis that pretreatment with albuterol will provide superior protection against breakthrough EIB in children with mild asthma compared to montelukast as maintenance therapy added to the current asthma regimen. Secondary aims of this study are to measure the effect of montelukast on leukotriene B4 (LTB4) concentrations as measured in EBC, and on inflammation measured by FeNO level. We hypothesize that since montelukast is a cysteinyl leukotriene receptor antagonist, patients with elevated concentration of LTB4 may have a greater response to this medication. Lastly, patients with elevated FeNO, a measure of airway inflammation respond differently to albuterol than montelukast his study is a randomized, double-blind, double-dummy, crossover clinical trial which will consist of 4 study visits and last up to 3 weeks.