Indoor environment and adverse health symptoms among children under home damp conditions

Building dampness and mouldy indoor environments are associated with the increase of approximately 30-50% in variety of respiratory and asthma-related health outcomes through a meta-analysis. The indoor environment related to indoor dampness is not be revealed yet, however it is important to provide the architectural techniques and optimal occupant behavior for prevention of dampness in buildings. The authors previously proposed an estimation method for home dampness using occupants self-reported answers to questions about visible vapor condensation, visible mould growth during winter. This dampness index ranges from 0 to 24, and its values were classified into four ranks (Rank 1 to Rank 4) based on quartiles from the results of a national questionnaire survey of about 5,000 houses in Japan. In order to clarify the association between home dampness and indoor environmental quality, questionnaire survey was conducted and several physical environmental items such as indoor temperature, humidity and microbial flora from the floor dust were measured in 120 detached houses located in East Japan.  This paper firstly describes the quantitative estimation of indoor dampness through the dampness index and the surveyed results from measured houses. The questionnaires also included items regarding the following health-related symptoms onset within 3 months among children. The dampness index is not following to normal distribution like a previous large scale questionnaire survey. And the prevalence of nasal symptoms (chi-square test: p < 0.01) and ocular symptoms increased as rank of dampness index was rising.  
Secondary, the characteristics of indoor temperature, humidity and microbial flora due to home dampness were clarified by comparing dampness index and measured results of these physical items. The microorganisms were genetically analysed to evaluate the population diversity of microbial species through the DNA analysed technologies. The median relative humidity in each dampness rank was higher at higher rank of indoor dampness. This tendency was statistically significant for both a living room and a bed room, and humidity ratio at rank 1 was significantly lower than that at rank 3 and rank 4. The fungal species of which the detection rate was increasing with ranks 1 to 4 of indoor dampness index were considered to be associated with indoor environmental problems of dampness. This paper indicates the association between indoor dampness and fungal species of Wallemia sebi and Rhodotorula glutinis.  
Finally, the association between adverse health effect and influencing factors related to indoor dampness was estimated using a multivariable logistic regression model. As results, it was revealed that children who were living in dampness are at significant risk for health-related symptoms such as nasal symptoms and dermal symptoms.