Dampness and mould in Chinese homes and sick building syndrome (SBS) symptoms - Associations with climate, family size, cleaning and ventilation

We investigated associations between dampness in Chinese homes and sick building syndrome (SBS) symptoms and studied the role of climate, family size, cleaning and ventilation for dampness, mould and SBS. A questionnaire survey was done in 2019-2020 among adults in five cities (32349 participants) and data on outdoor climate was collected. Multilevel logistic regression was used to calculate adjusted odds ratios (ORs). In total, 2.2% had rhinitis, 1.8% eye, 1.6% throat and 2.9% skin symptoms, 2.1% headache and 8.7% fatigue (weekly symptoms). Overall, 12.1% reported indoor mould, 5.7% damp bedding, 5.3% mould odour and 33.8% humid air in current home. Mould was associated with all symptoms (ORs 1.86-2.15 for minor mold growth and 1.65-3.45 for major mould growth). Damp bedding was associated with all symptoms (ORs 2.18-2.80 for minor dampness and 2.51-8.03 for major dampness). Mould odour was associated with all symptoms (ORs 1.84-2.77 for sometimes odour and ORs 3.78-7.80 for weekly odour). Perception of humid air was associated with all symptoms. ORs increased by number of dampness signs. Precipitation, outdoor relative air humidity and temperature increased dampness, mould and SBS symptoms. Large family size increased dermal symptoms. Daily floor cleaning, airing in winter, putting bedding to sunshine and mechanical ventilation in the bathroom reduced dampness, mould and SBS symptoms. In conclusion, mould and dampness in Chinese homes can increase rhinitis and SBS-symptoms in a dose-response manner. A warmer and more humid climate can increase, and cleaning and ventilation in the home can decrease dampness, mould and SBS symptoms.