Case-Control study for the Association Between Indoor Environmental Factors and Children’s Health Problems in Japan – Part 2 Results of Measurements during Rainy Season and Winter

In order to clarify the association between indoor environmental factors and children’s health problems, indoor air quality was investigated during the winter and rainy seasons in Japan. The total of 209 houses was classified into case and control groups whether the child have allergy symptom or not. The number of the houses in case and control groups is 133 and 76, respectively. This survey included measurement of indoor temperature, humidity, the pollution of chemical compound and mite allergen (Der 1). These measurements were conducted in the living room and children’s room. It was found that the excess rate of relative humidity 70% in the case group was higher than that of the control group. During rainy season, in most houses (87.5%) Der 1 concentrations exceeded the proposed thresholds of allergic sensitization. The Der 1 concentration of the case group was higher than the control group. It was concluded that the chemical concentration including HCHO was less than the recommended value in many houses. On the other hand, Der 1 exceeded the proposed thresholds of allergic sensitization in the winter and rainy seasons.