The study will entail two to three visits. On visit 1 (V1) all individuals will sign informed consent to participate in the study under an NYU IRB approved protocol. A questionnaire will be completed with standardized questions that include information on WTC exposures, demographics, presence and severity of respiratory symptoms, tobacco history and past medical history. Individuals will undergo spirometry with inhaled bronchodilator. Individuals will undergo methacholine challenge test (visit 1a) if they have normal spirometry or no bronchial hyperresponsiveness. On visit 2, individuals will return to undergo ENO, EBC and spirometry with pre and post bronchodilator maneuvers and induced sputum. Blood will be obtained for CBC with differential cell count, and assessment of total IgE and allergen-specific IgE. Blood will also be stored for future analysis of inflammatory markers. Based on experience, there have been individuals unable to produce enough sputum and thus yield too small a number of cells. These individuals are excluded from data analysis. In addition, there will also be subjects who are able to produce sputum and return for repeat sputum testing.