Ultraviolet germicidal irradiation (UVGI) is a sterilization method that uses ultraviolet (UV) light at sufficiently short wavelength to break down microorganisms. It is used in a variety of applications, such as food, air and water purification. UV has been a known mutagen at the cellular level for more than one-hundred years. The 1903 Nobel Prize for Medicine was awarded to Niels Finsen for his use of UV against tuberculosis.
UVGI utilises the short wavelength of UV that is harmful to microorganisms. It is effective in destroying the nucleic acids in these organisms so that their DNA is disrupted by the UV radiation. This removes their reproductive capabilities and kills them.
The wavelength of UV that causes this effect is rare on Earth as its atmosphere blocks it. Using a UVGI device in certain environments like circulating air or water systems creates a deadly effect on micro-organisms such as pathogens, viruses and molds that are in these environments. Coupled with a filtration system, UVGI can remove harmful micro-organisms from these environments.
The application of UVGI to sterilization has been an accepted practice since the mid-20th century. It has been used primarily in medical sanitation and sterile work facilities. Increasingly it was employed to sterilize drinking and wastewater, as the holding facilities were enclosed and could be circulated to ensure a higher exposure to the UV. In recent years UVGI has found renewed application in air sanitization.
I sistemi a raggi ultravioletti non possono essere considerati sterilizzanti, hanno principalmente una azione batteriostatica, mantenimento di sterilità (antisettico fisico). Sono utilizzate soprattutto per la batteriostaticità dei piani di lavoro o dell'aria sotto cappa. Non hanno grande capacità di penetrazione per questo sono efficaci solo su oggetti non troppo spessi o su liquidi fatti passare attraverso recipienti sottili. Devono essere utilizzate con cautela e a distanza dagli operatori, essendo agenti mutageni e estremamente dannosi per gli occhi. Sono prodotte da lampade a vapori di mercurio.