Two routes for pollen entering indoors: ventilation and clothes.

BACKGROUND The route by which pollen enters dwellings has not been clarified. OBJECTIVE To evaluate the amount of pollen entering dwellings by ventilation and adhesion to textile products. METHODS The amount of pollen clinging to fabrics (clothes, laundry, and futon bedding) out of doors was measured by quantification of Japanese cedar pollen antigen Cry j 1. The effect of air ventilation on the amount of pollen indoors was also investigated using several neighboring unoccupied apartments with an identical layout while controlling the ventilation conditions. RESULTS The amount of pollen adhering to futons was especially high. More than half of the pollen on futons or laundry remained on the surface, even after being brushed off by hand or shaken off. Vacuuming laundry and futons after airing out would be an effective way to decrease the amount of indoor pollen. A large amount of pollen entered dwellings through air ducts when the windows were closed and the ventilation fans working. Since most pollen that entered by ventilation remained near the windows, cleaning carefully and frequently near windows could reduce the amount of pollen indoors. CONCLUSIONS To decrease the amount of pollen indoors, special attention must be paid to textile products and ventilation systems during the pollen season.