Efficacy of Face Mask in Reducing Respiratory Allergic Symptoms in Birch-allergic Subjects in ALYATEC Exposure Chamber

Main Inclusion Criteria: * Subjects who signed the written informed consent, * Subjects covered by health social identification number, * Subjects able to understand and complete study-related procedures, * Subjects reported history of symptomatic birch pollen allergen-triggered asthma (GINA1) with associated allergic rhinitis, * Positive skin prick test (SPT) with cat hair extract with mean wheal diameter ≥ 5 mm compared to negative control (NaCl reaction \< 2 mm), * Positive sIgE tests for birch tree pollen and Bet v 1 (≥0.7 kUa/L), * Subjects with FEV1 ≥ 70% predicted at screening and before allergen exposure, * Subjects with at least one drop in FEV1 ≥20% during the 1-hour baseline exposure * ACT≥ 20, * Women of childbearing potential with a negative pregnancy test throughout the study period and a highly effective contraception: oral contraceptives, condom with spermicide, intrauterine device, bilateral tubal ligation, vasectomized partner. Main Exclusion Criteria: * Allergen immunotherapy to birch pollen allergen for more than 1 month in the 3 years prior to the screening visit, * Ongoing allergen immunotherapy to another allergen, * History of anaphylactic reactions to birch allergen exposure or birch allergen immunotherapy, * History of anaphylactic reactions to another allergen in the last 6 weeks before inclusion, * Nasal polyposis, deviation of nasal septum or diagnosis of uncontrolled non-allergic rhinitis, * Subjects allergic to indoor environmental allergens (molds, house dust mite allergens) with obvious exposure to these allergens causing allergic symptoms,