What is UVC light ?
Ultraviolet rays (UV) are a form of electromagnetic radiation, shorter than that of visible light but longer than X-rays. As can be seen from the electromagnetic spectrum, the UV radiation is divided into several regions based on their wavelength, which is measured in nanometers (nm= 0.000000001 meters). Of primary interest are the first three bands designated as UV-A, UV-B, and UV-C which have different biological effect as shown in the table.
UV radiation is classified into three different wavebands that have somewhat different biological effects:
|100 to 280 nm – Called ‘germicidal’ radiation because of its ability to kill bacteria and inactivate viruses. UVC can cause injury to the skin (e.g. erythema, also known as sunburn) and eye (i.e. inflammation of the cornea or photokeratitis). Solar UVC is blocked by the ozone layer in the atmosphere, so does not reach the earth’s surface.|
|280 to 315 nm – Waveband most associated with sunburn, skin cancer and cataracts.|
|315 and 400 nm – Waveband most associated with skin aging; can cause other effects depending on the dose received and the presence of any photosensitizer.|
The main source of UV radiation is the sun. However, when reaching the Earth’s atmosphere, all UV-C and approximately 90% of UV-B radiation is absorbed by ozone, water vapour, oxygen and carbon dioxide. Differently, UV-A is less affected and most of it travels through the atmosphere and reaches the Earth’s surface, with a small UV-B component. While UV-B exposition has some benefits for people, including the creation of Vitamin D, it also can cause health risks. Overexposure to UV radiation can lead to serious health issues, including skin cancer and potentially blinding eye diseases if adequate protections are not used.
The germicidal effect of UV-C
For several decades, UV-C has been used as a germicide for disinfecting water, which means that it is able to inactivate several microorganisms, such as bacteria, viruses and protozoa. Recently, UV-C have been intensively studied and recognized as an alternative to conventional disinfection procedures in hospitals. Most UV disinfection devices primarily use UV-C radiation with wavelengths between 200 and 270 nm. At particular wavelengths such as 254nm, UV-C light is able to destroy molecular bonds and disrupt DNA or RNA via the dimerization of pyrimidine, causing the death of various environmental microorganisms.
The UV-C disinfection method offers several advantages over conventional disinfection methods, including germicidal activity on broad-spectrum organisms, shorter lead time for vegetative bacteria, and safe and environmentally friendly use without harmful chemical residues. In addition, this method reduces human error and saves on labor costs due to a relatively simple installation and operation mode in healthcare facilities. However, if used directly on humans, UV-C can be harmful to the skin and eyes. Therefore, to ensure safety, it is recommended that only trained operators perform the disinfection procedure.
UV-C radiation can be produced artificially from low pressure mercury, xenon lamp, Excimer lamps and UV-C LEDs. A variety of systems are commercially available today. However, the performance of different UV-C devices varies and may require different exposure times to inactivate microorganisms. A selection of reliable products has been made by our team and is presented in our catalog.
The FAR-UVC 222 nm Technology
Recently, interest has emerged for the FAR UV-C light technology (207–222nm) because it potentially has the same germicidal and highly effective properties as 254nm light, but without the associated risks to human health. This is because due to the shorter wavelength, the ability of 222nm light to penetrate biological materials is very limited. It is reported that FAR UV-C light cannot penetrate the human stratum corneum (the outer layer of the skin of dead cells), the tear ocular layer, or even the cytoplasm of individual human cells. Therefore, FAR UVC light cannot reach or damage living cells in human skin or human eye, unlike conventional germicidal UV light. However, this limited penetration remains larger than the size of viruses and bacteria, making FAR UVC light just as effective at inactivating these pathogens as conventional germicidal UV light.
Numerous studies are currently underway on the germicidal efficacy and dangerous health effects of 222 nm technology. At the moment, this technology is not yet widely available in Europe. In addition, care must be taken as there is evidence that some models may have minor emissions at a longer wavelength, which is dangerous and would represent a risk of use in the presence of humans.
Our team is following with interest the progress of the 222 nm technology and the evolution of certifications between different countries. Particular attention is paid to discussions on this subject in the scientific community, in order to always guarantee the safety of the products advertised in our catalog.
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FAR UV-C REFERENCES
M. Buonanno, D. Welch, I. Shuryak, and D. J. Brenner, “Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses,” Sci. Rep., vol. 10, no. 1, Jun. 2020.
K. Narita et al., “Ultraviolet C light with wavelength of 222 nm inactivates a wide spectrum of microbial pathogens,” J. Hosp. Infect., vol. 105, no. 3, pp. 459–467, Jul. 2020.
M. Buonanno et al., “Germicidal efficacy and mammalian skin safety of 222-nm UV light,” Radiat. Res., vol. 187, no. 4, pp. 483–491, Apr. 2017.
D. Welch et al., “Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases,” Sci. Rep., vol. 8, no. 1, Dec. 2018.