Civil air defense projects, underground fortifications, underground bunkers, and headquarters, due to environmental constraints, electrical lighting must be used inside the project, coupled with factors such as moisture on the walls of the enclosure structure and radon-containing radioactive materials, which will have a long-term life in civil air defense projects. The personnel have a physical and psychological impact. Because radon is an invisible and intangible serious carcinogen, it is difficult for people to feel its existence and easy to ignore its harm. Therefore, radon pollution is an "invisible killer" and the "culprit" of air pollution in underground facilities of civil air defense projects ".