Issues on humidity environment and health problem

Japan is characterized by high humidity in summer and low humidity in winter. Therefore, summer is in a climatic condition where mold is easy to grow, and in fact, mold damage is occurring. Due to improvement of the thermal insulation and airtightness of houses, the temperature in the room is maintained high even in winter, and mold damage occurs. We will introduce the research we have conducted regarding humidity environment and health problems, and discuss future subjects. The outline is as follows. 

1. The results of long-term measurements on the temperature and humidity environment of houses in regions with different climatic conditions are shown, and it is stated that the humidity environment is significantly different in each region and house. In addition, the mold index was used to investigate the possibility of mold generation. 
2. A survey was conducted on approximately 5,000 homes nationwide regarding the relationship between dampness and children's health. Condensation and mold often occur on the surfaces of the outer walls, window glass, and windows frames. It was found that the higher the dampness index based on condensation and mold occurrence, the more the prevalence of allergic diseases such as allergic rhinitis and atopic rhinitis. 
3. A survey on relationship of low humidity with dryness and health effects in winter was conducted on approximately 4,000 houses nationwide. As a result, the rate of feeling dryness was about 60%, and the rate of responding that health was affected was 23% of the whole. However, there are occupants that feel dryness even in houses with high relative humidity, and it is found that the feeling of dryness is not always due to low humidity. It is also found that the effect of air pollution cannot be ignored. 
4.  From the above, it is necessary to improve the thermal insulation performance to solve the problem of dampness, and controls of humidity and air quality are important to prevent a sense of dryness. Also it is noted that the factors affecting the feeling dry need to be further studied.