There is a great deal of interest in the use of ultraviolet light to mitigate germs and viruses. The technology of germicidal lighting is referred to as germicidal UV, or GUV. Technically, the GUV spectrum is defined as UV-C. While the UV-C part of the spectrum is an effective killer of COVID-19 and similar viruses, it must be used carefully to be both effective and safe. Information on this site is compiled to help promote the safe and effective use of GUV in residential settings.