[Protracted (lasting) presence of Japanese cedar pollen allergen (Cry j I) in house dust].

We investigated the relationship between the amounts of Cry j I in house dust and airborne Cryptomeria japonica pollen in the same location. Cry j I was still detected in house dust collected two weeks after airborne C. japonica pollen had disappeared. Disappearance of Cry j I in house dust coincided with the disappearance of symptoms in the C. japonica pollinosis patients who lived in the same area. Airborne Cupressaceae pollen appeared during the latter half of the C. japonica pollen season. Disappearance of Cupressaceae pollen did not coincided with the disappearance of the symptoms in C. japonica pollinosis patients. Therefore, some symptoms of C. japonica pollinosis patients after C. japonica pollen disappeared from the air may be caused by pollen which had attached to clothes and been brought indoors.