“Dampness” and “Dryness”: What is important for children's allergies? A cross-sectional study of 7366 children in northeast Chinese homes

This study investigates associations of building dampness indicators, and perceptions of moldy odor, humidity and dryness (Dampness and Dryness, D&D) with children's asthma and allergies. Data were obtained from a cross-sectional study in Tianjin and Cangzhou, China from 2013 to 2014. Completed surveys were returned by 7366 families with children 0-8 years old. We studied D&D factors both in the current residence and the residence where the children lived immediately after birth. A total of 4.4% of the children had doctor-diagnosed asthma; 9.5% had doctor-diagnosed rhinitis; and 39.1% had doctor-diagnosed eczema. Most of the dampness indicators, perceptions of odors, and perceived dryness, were significantly associated with children's asthma and allergies. A reporting bias in parents (or guardians) who themselves had allergies was not found to be the reason for the associations between D&D and health effects. Compared with either previous or current exposure to D&D, continuous exposure to D&D was a greater risk for children's asthma and allergies. Perceived dryness was the most important studied risk factor for children's allergies in either current or previous homes.