Abstract
In this paper, indoor air environment is focused as one factor in causing environmental hypersensitivity, and the countermeasures against sick house syndrome, the state of poor ventilation in buildings and the influence of poor ventilation in buildings on COVID-19 infection are reported. Japanese traditional wooden buildings are suitable for the hot and humid weather. However, the improvement of the buildings for better living environment and energy saving has been made and buildings have become more and more airtight and new building materials using chemical compounds are used. This has changed indoor air environment little by little and sick house syndrome occurred in such an environment. These changes brought disparity in ventilation characteristics and indoor air environment in houses in Japan. In many types of airtight buildings, indoor air quality has been deteriorated by the inadequate operation of ventilation and air conditioning systems for energy saving and cost saving. Investigations on indoor air environment in buildings where COVID-19 outbreaks occurred, have revealed that the buildings were not ventilated enough because of the poor construction work and the lack of maintenance of the ventilation and air conditioning systems. The consideration of this state of poor ventilation in buildings will suggest effective countermeasures against environmental hypersensitivity.
