Sample size: 40 participants in the two groups. Intervention: Each subject will undergo evaluation including a respiratory questionnaire, pulmonary function tests, methacholine challenge test with determination of PC20, exhaled nitric oxide (eNO), and exhaled breath condensate (EBC). Venous blood will be analyzed for complete blood count + eosinophils, IGE levels, and Vitamin D levels. Prick skin test for inhaled allergens will be performed. All measurements will be evaluated in a single 3 hour visit, with no follow up study visits.