Ultraviolet light (UV) is a type of naturally present electromagnetic radiation that forms a part of sunlight and makes up approximately 10% of the total light generated by the sun. UV light has three wavelength categories: UV-A, UV-B and UV-C light. Nearly all the UV radiation that reaches Earth is UVA, because most of UV-B and all UV-C light is absorbed by the ozone layer. And it is exactly UV-C, which has the shortest wavelength and the highest energy, that can act as a disinfectant.
The disinfection properties of UV-C lighting have been known for over 140 years, since Downes and Blunt  discovered the antibacterial effects of the shorter wavelengths of sunlight. Scientist Niels Ryberg Finsen was awarded the Nobel Prize for Medicine in 1903 for inventing Finsen UV curative lamp .
After confirming UV light’s ability to kill microorganisms, the next step was to find a way to replicate the appropriate UV wavelengths that would result in the disinfection of surfaces, air, and water. The first UV QUARTZ lamp was invented in 1904 in Hanau near Frankfurt, Germany .
The application of Ultraviolet Germicidal Irradiation (UVGI)* to disinfection has been an accepted practice since the mid- 20th century. It has been used primarily in medical sanitation and sterile work facilities. UV-C light has been used extensively in disinfecting drinking water, wastewater, air, pharmaceutical products, and surfaces.
UV-C light technology has been proven to be capable of destroying viruses, bacteria, mould and fungi in many hundreds of laboratory studies worldwide. All bacteria and viruses tested up to date (many hundreds over the years, including the recent SARS-CoV-2 (“Covid 19”) virus, are destroyed by UV-C light. Some organisms are more susceptible to UV-C disinfection than others, but all that were tested so far were destroyed at the appropriate doses.
Although the science behind UV-C technology has been around for a very long time, it has not been widely used in the world for commercial use until recently. Latest technological advancements have now made this possible.
*UVGI – Ultraviolet Germicidal Irradiation is a method of disinfection
that uses short wavelength ultraviolet light (UV-C) to inactivate or kill
microorganisms and pathogens.
A quartz lens from a Finsen UV lamp (1903).
UVGI primarily used in medical sanitation