“…1,2 Regarding airtightness, apartment buildings are more airtight than detached houses, resulting in increased condensation, mold, and dampness. 20 The Swedish BETSI (Building, Energy use, Technical Status, and Indoor environment) study [3][4][5][6][7] surveyed 5775 adults aged 18 years and older living in apartments (4369 households) and found that these factors (dampness, mold, and condensation), especially in rental apartments, increase the risk of rhinitis, asthma, and respiratory infections 3 as well as the risk of eye, nose, throat, and skin symptoms, headaches, and fatigue. 6 In addition, because the residential environment of apartments varies depending on the location of units and number of floors in a building, there are several issues that do not exist in detached houses.…”