Ultraviolet light has shorter wavelengths than visible light. The light from such electromagnetic radiation can be separated into various ranges:
1. UVC-UV of short range considered “germicidal UV”.
2. UVB-UV of longer wavelength considered harmful for human, such as sunburn or sun glare.
At certain wavelengths UV is mutagenic to bacteria, viruses and other micro organisms. At a wavelength of 2,537 Angstroms (254 nm) UV will break the molecular bonds within micro-organismal DNA, producing thymine dimers in their DNA thereby destroying them, rendering them harmless or prohibiting growth and reproduction.
Micro-organisms have less protection from UV and cannot survive prolonged exposure to it. Ultraviolet germicidal irradiation system is designed to expose environments such as water tanks, sealed rooms and forced air systems to germicidal UV.
Exposure comes from germicidal lamps that emit germicidal UV electromagnetic radiation at the correct wavelength, thus irradiating the environment. The forced flow of air or water through this environment ensures the exposure.