Comparison of an effect of the secondgeneration antihistamines with deiffenrent configuration for Japanese cedar pollinosis (the randomized, placebo controled, double blind study using an environmental challrenge chamber)

INTERVENTION: The group which took desloratadine (5mg)on the day before of pollen exposition The group which took levocetirizine (5mg) on the day before of pollen exposition The group which took placebo on the day before of pollen exposition CONDITION: Japanese cedar pollinosis PRIMARY OUTCOME: Total nasal symptom score when Japanese cedar pollen exposition was performed for 3 hours in the environmental challrenge chamber INCLUSION CRITERIA: 1)Patients who have medical history of cedar pollinosis for more than 2 years. 2)Patients who do not have nasal symtoms induced by any allergen and requier any drug treatment out of Japanese cedar pollen scattering season. 3)Positive specific IgE to cedar pollen allergen(>=class2) 4)Patients who develop more tha derate symptoms by a pollen exposure for 3 hours.