 Allergic rhinitis is an inflammatory disorder of the upper airway that occurs following allergen exposure. The focus of this study, seasonal allergic rhinitis SAR, is one type of allergic rhinitis that is triggered by the pollen from trees, grasses, and weeds. Commonly referred to as hay fever, it is characterized by sneezing, nasal congestion and pruritus, rhinorrhea, and pruritic, watery, red eyes. The purpose of this study is to evaluate the onset of action of an investigational nasal spray, GW685698X aqueous nasal spray, versus vehicle placebo nasal spray in the treatment of seasonal allergic rhinitis caused by ragweed following a single dose of treatment in controlled pollen concentrations in an allergen challenge chamber. 