Phthalates are plasticizers or softeners, used in PVC and other plastics and a range of consumer products. Since phthalates are not chemically bound to the plastic they leak out from these products, causing routine human exposure through air, dust and food. Exposure to phthalates has been linked to worsening or development of airway diseases in epidemiological studies, but the effects of phthalates on our airways and immune responses are largely unknown. In this study we would like to investigate how one particular phthalate, dibutyl phthalate (DBP), can affect the human respiratory and immune systems. The investigators are not expecting that the responses will be noticeable to the subjects; they are expecting that any responses that may occur will only be detectable through careful examination of cells and tissues (e.g. nasal lavage and brushes (fluid from the nose), bronchial samples, blood, urine). Nasal samples will be used for measurement of nasal inflammatory responses in terms of cell recruitment and levels of inflammatory mediators. Bronchial samples will allow for a refined examination of an inflammatory responses in the lung and thus provide a much more detailed information concerning the phthalate-induced responses due to allergen challenge. Understanding these subtle changes will help us prevent health problems associated with phthalate exposure in the future.