Natural disasters such as strong wind, flood, landslide, and earthquake happen more frequently than ever and their damage is increasing Human-caused disasters such as fire, explosion, and collapse also happen on a large scale. Outside plant facilities including telecommunication buildings are exposed to these disasters and may be affected adversely, which implies that preventive measures are needed. Recommendation ITU-T L.391 deals with monitoring systems to mitigate damage and protect outside plant facilities against disasters.