Determination of Grass Pollen Allergen Concentration Inducing Rhinoconjunctivitis Symptoms in Subjects Allergic to Grass Pollen in ALYATEC Allergen Exposure Chamber

"After the screening visit, subjects are randomized into 3 groups presenting a sequence of allergen concentrations with randomly defined concentrations of Ph l p 5 (0, 30, 60 and 90 ng/m3).~Each participant undergo four different 3-hour exposure sessions to grass pollen allergen corresponding to the four different allergen concentrations."