Relationship between natural ventilation modes and indoor/outdoor ratio of Japanese cedar pollen and Cry j 1 allergen

Japanese cedar pollen and its Cry j 1 allergen are major drivers of hay fever in Japan. This study conducted field measurements in an apartment room in Tokyo (Japan) to investigate the effect of indoor air changes per hour (ACH) on the indoor/outdoor (I/O) ratio of Japanese cedar pollen and Cry j 1 at different locations, as well as the variation in Cry j 1 particle size under four opening modes of the balcony door and window. A total of 220 pollen and 484 allergen samples were analyzed. Japanese cedar pollen and Cry j 1 allergens were present even when all doors and windows were closed. The I/O ratio of the Cry j 1 allergen tended to decrease with increasing ACH, and Cry j 1 particles <7 mu m in diameter were commonly recorded. This study elaborates on the indoor-outdoor transportation dynamics of Japanese cedar pollen and Cry j 1 allergen in a conventional domestic setting and identifies potential areas for improvement in indoor allergen detection and filtering methods.