In 1800, a German astronomer, Fredrich William Herschel, was experimenting with passing sunlight through a glass prism. He observed that temperatures increased the more he went towards the red end of the spectrum. As a scientist he measured beyond the red end of the spectrum, naming it “ultra-red.”
A year later, Johann Wilhelm Ritter, Polish-born physicist, hearing of Herschel’s ultra-red discovery, wanted to know if light existed beyond it. At the University of Jena, Ritter did experiments using silver chloride. This light-sensitive material was used in passing different colors through a glass prism. He found an intense reaction with the silver chloride, and beyond the red end of the spectrum he found the violet light that he termed “chemical rays.” Later this light was referred to as “ultraviolet” light.
In 1877 two English scientists, W. B. Hugo Downes and Thomas Porter Blunt, discovered that sunlight kills bacteria. While doing an experiment with sugar water the part in the sun remained clear while the shaded side grew cloudy with bacteria.
Much later Marshall Ward discovered it was the ultraviolet portion that had the bacteria-killing properties.
Niels Finsen was awarded the Nobel Prize for Medicine in 1903, for his work using UV light to fight tuberculosis.
The UV-C light sterilization has the ability to kill viruses, germs, and bacteria. The lights are now at a stage that we have sizes that we can use anywhere.
Further, Public Health Reports describes how we are using UV light for germicidal purposes:
Public health concerns such as multi- and extensive drug-resistant tuberculosis, bioterrorism, pandemic influenza, and severe acute respiratory syndrome have intensified efforts to prevent transmission of infections that are completely or partially airborne using environmental controls. One such control, ultraviolet germicidal irradiation (UVGI), has received renewed interest after decades of underutilization and neglect. With renewed interest, however, come renewed questions, especially regarding efficacy and safety. There is a long history of investigations concluding that, if used properly, UVGI can be safe and highly effective in disinfecting the air, thereby preventing transmission of a variety of airborne infections. Despite this long history, many infection control professionals are not familiar with the history of UVGI and how it has, and has not, been used safely and effectively. This article reviews that history of UVGI for air disinfection, starting with its biological basis, moving to its application in the real world, and ending with its current status.