IAQ in a school building with moisture problems

This case study investigates the effects of ventilation intervention on measured and 12 perceived indoor air quality (IAQ) in a repaired school where occupants reported IAQ problems. 13 Occupants ́ symptoms were suspected to be related to the impurities leaked indoors through the 14 building envelope. The study’s aim was to determine whether a positive pressure of 5-7 Pa prevents 15 the infiltration of harmful chemical and microbiological agents from structures, thus decreasing 16 symptoms and discomfort. Ventilation intervention was conducted in a building section comprising 17 12 classrooms and was completed with IAQ measurements and occupants ́ questionnaires. After 18 intervention, the concentration of total volatile organic compounds (TVOC) and fine particulate 19 matter (PM2.5) decreased, and occupants ́ negative perceptions became more moderate compared to 20 those for other parts of the building. The indoor mycobiota differed in species composition from the 21 outdoor mycobiota, and changed remarkably with the intervention, indicating that some species 22 may have emanated from an indoor source before the intervention. 23