What is UVC radiation and how does it work?
Ultraviolet (UV) light is a type of electromagnetic radiation that comes from the sun and transmitted at different wavelengths and frequencies. UV light falls in the range of the electromagnetic (EM) spectrum between visible light and X-rays, making them invisible to the human eye.
There are three types of UV radiation according to their wavelength. The shorter the wavelength, the higher the energy of the UV radiation. Short-wavelength UVC is the most damaging type of UV radiation. However, it is completely filtered by the atmosphere and does not reach the earth's surface. UVC radiation is used as air disinfectant because it has no toxic byproducts, does not produce unwanted odor, and does not require storage of hazardous chemicals.
Medium-wavelength UVB is very biologically active but cannot penetrate beyond the superficial skin layers while the relatively long-wavelength UVA accounts for approximately 95 percent of the UV radiation reaching the Earth's surface.
UVC Inactivates Coronavirus
UV radiation breaks the chemical bonds of microorganisms (virus, bacteria, moulds, etc.) using radiation energy. Ultraviolet radiation (UVC) produces molecular photo-chemical reactions. The absorption of UV photons between 250 and 270 nm causes the DNA molecular dissociation that damages the cell membrane and nucleus of the microorganisms.
It causes local mutations and prevents the reproduction of microorganisms until they are inactivated and killed. Therefore, UV radiation is used in the process of decontamination to destroy germs especially those considered as pathogenic.
UVC radiation at 253.7 nm is germicidal. Germicidal means the destruction of microorganisms like viruses, bacteria, yeasts, worms, and molds. The germicidal effectiveness of UV radiation is in the 180-320 nm region with an optimum at 265 nm.
The graph showed that low-pressure, mercury-arc germicidal lamps radiated approximately 95% of the energy at the 253.7 nm line which is the most effective one for germicidal applications. The graph showed this radiation output is remarkably close to the peak of the germicidal effectiveness curve of 265 nm, the most lethal wavelength for microorganisms.
UVC radiation using germicidal lamps is being used extensively in air purification such as in professional air purifier systems, food and beverage, medical applications, and pharmaceutical applications.
In addition, photocatalysis with the use of UVC lamps is highly effective in the air treatment of contaminated laboratories, hospitals, and medical facilities.