UVC is short-wave, ultraviolet radiation in the optical frequency range with shorter wavelengths than the light visible to humans. It is part of the non-visible segment of the ultraviolet spectral band between 100 and 280 nm.
The electromagnetic spectrum contains visible and invisible wavelength ranges. UVC is at the short-wave end of the spectrum and is invisible to the human eye. Although no visible light is emitted, it is nevertheless referred to as “ultraviolet light”.
One of the key properties of the UVC spectral wavelength range is that this radiation energy, when placed within range of a surface, deactivates viruses, bacteria and mould spores. UVC is therefore referred to as germicidal ultraviolet irradiation (GUVI).
No, in fact germicidal ultraviolet radiation has been studied since the late 19th century, and with a focus on UVC radiation from around 1930. In 1935, scientists proved through various tests the ability of UVC radiation to effectively deactivate microorganisms in the air. In the 1970s, UVC irradiation was shown to reduce tuberculosis infections. Since the early 1990s, much research and development has focused on improving the efficiency and safety of UVC products as a means of deactivating viruses and bacteria. UVC technology is a proven and useful tool for combating microorganisms.
Various scientific studies have demonstrated high efficacy in reducing hazardous microorganisms when the technology is applied according to manufacturer recommendations.
For example: “Implementing this no-touch technology has led to sustained reductions in microbiological contamination of surfaces, reduced contamination transmission and reduced the spread of drug-resistant bacteriological infections in several hospitals. In the study by Liscynesky et al , a total of 32 out of 238 (13%) “high-touch surfaces” in hospital rooms with proven contamination by C. difficileinfection (CDI) pathogens tested positive after cleaning with disinfectants. Only 1 of the 238 (0.4%) surfaces tested positive after application of UVC disinfection (the computer keyboard) after 3 compounded 254nm wavelength emitters were active for 45 min.” [Evaluation of a “high touch surface” disinfection with an ultraviolet C (UVC) LED emitter in critical areas of hospitals, Beatrice Casini et al, September 24, 2019]
Germicidal ultraviolet irradiation demonstrably destroys or deactivates microorganisms such as coronavirus SARS – CoV-2 / COVID-19, bacteria, mould spores, yeasts or viruses. With appropriate UV doses (mJ/cm²), a neutralisation efficiency of up to 99.9% can be achieved.
As soon as UVC rays come into contact with microorganisms, photochemical reactions are triggered while the radiation is absorbed. This is followed by a destruction of the microorganism’s DNA. In principle, the absorption of the photons prevents the replication (duplication) of the DNA.
Because Covid-19 is so new, there are still many test series currently being conducted around the world. However, recent research at Columbia University in the USA concludes that UVC irradiation is an efficient method to combat and eliminate the virus.
Tests carried out recently and after the outbreak of the Corona pandemic at the Institute of Medical Virology at the University Hospital in Frankfurt also showed that irradiation of Corona viruses with UVC discharge lamps as well as with UVC LEDs resulted in a virus killing rate of up to 99.4 per cent.
The structure of the SARS-CoV-2 coronavirus is very similar to that of other corona viruses, including MERS. There is no evidence that UVC radiation should not be an effective disinfection method to combat Covid-19. It has been proven that UVC irradiation is a very good method for the deactivation of viruses such as MERS or SARS, which are closely associated with Covid-19.
UV products use low pressure (Hg) mercury discharge tubes. These tubes produce UVC radiation at a wavelength of 253.7nm, which is currently the closest technically feasible to the most effective range for deactivating microorganisms (260 to 265nm). This makes direct and indirect disinfection lamps well suited for germicidal ultraviolet irradiation.
No, unlike other disinfection methods such as chlorination etc., UVC rays do not produce any by-products, substances or other residues. According to Philips (UVC tube manufacturer), for example, no residues of substances have been detected after UVC disinfection.
Position your UVC lamp so that it covers the area to be disinfected as well as possible. To do this, select the correct product with the appropriate power class and set the correct time on the device in relation to the area to be disinfected on the UVC radiator. Please make absolutely sure that the UVC radiator stands securely on a solid surface or is otherwise firmly installed. Please ensure that areas within the surface to be disinfected that are covered by “object shadows” cannot be disinfected. For the disinfection of a surface, we therefore always recommend the simultaneous use of several spotlights that act from different directions in order to largely exclude shadows.
UVC lamps are designed in such a way that, when optimally directed at a surface to be disinfected and when the appropriate disinfection time for irradiation is preselected, 99.9% of the microorganisms present can be killed or deactivated within the disinfection beam. However, it is recommended to combine the disinfection measure by UVC irradiation in problem areas with other disinfection methods. For example, one or more UVC lamps can never be set up or aligned in such a way that they disinfect a door handle on all sides. Here, subsequent manual disinfection of selected “heavily used” areas is necessary.
A surface to be disinfected by UVC radiation should be dust-free before treatment so that the UVC radiation can reach the surface of the object to be treated unhindered.
This depends on the UVC lamp model (which defines the energy emitted for germicidal ultraviolet irradiation) and the selected time for UVC irradiation of the surface to be disinfected.
Incorrect use and improper installation can cause UVC products to limit safety. Always follow the instructions in the user manual. UVC technology has been extensively researched and described scientifically. Compared to UV-A and UV-B radiation, both of which are part of the sunlight hitting the earth, UVC radiation does not penetrate very deeply into the skin due to the scattering that increases with shorter wavelength. UVC radiation is absorbed in the upper, mostly dead layers of human skin. The daily maximum of 253.7nm wavelength radiation to which a human should be exposed is 6 mJ / cm2 over an 8-hour period [American Conference of Governmental Industrial Hygienists. 2020 Threshold Limit Values and Biological Exposure Indices]. This UV radiation exposure is comparable to a 10-minute bath in direct sunlight with a UV index of 10.
Regardless, UVC radiation can cause temporary skin and eye irritation as well as redness. Prolonged exposure to UVC radiation can cause burns.
Therefore, when operating ultraviolet disinfection lamps, NO people, animals or plants should be in the rooms to be disinfected.
Material properties of objects exposed to direct UVC radiation may undergo a faster ageing process. This is comparable to the change in material properties when these objects are exposed to direct sunlight.
After using UVC lamps for disinfection in closed rooms, the respective room must be ventilated for approx. 10 minutes. Several safety precautions are integrated in the UVC disinfection lamps to largely exclude improper use and to minimise the risk of injury.
NO. People and animals should not be in the same room when a UVC direct emitter is activated. When handling UVC radiation producing luminaires, suitable safety goggles and nitrile gloves must be worn and opaque, close-fitting clothing must cover all skin surfaces.
When replacing UVC lamps, the luminaire should always be disconnected from the power supply and the same safety precautions as above apply.
Almost 100% of UVC radiation is blocked by window glass. Window glass is made of various components. One of these components is cerium oxide: a compound that blocks UVC radiation. The material used for the production of UVC light tubes is quartz glass, which contains only one component of silicone dioxide. This allows UVC rays to pass through. For this reason, the radiation generated in the UVC bulb can pass through the glass envelope, but not through a window. Further information can be found at https://www.iuva.org/UV-FAQs.
This depends on the nature and composition of the material. Some transparent plastics will allow UVC radiation to pass through, others will not. It should be mentioned, however, that effective penetration of materials is only possible if the corresponding material surfaces are as pure as possible (reason why quartz glass with only one component silicone dioxide is used for the production of lamp covers). From this it can be deduced that most transparent materials do not allow UVC radiation to pass through.
Opaque / frosted materials and tightly woven fabrics also have a blocking effect of UVC rays.
UV light generally has an ageing effect on certain materials such as paints, colours in fabrics or some plastics. Polypropylene (PP) and soft polyethylene are plastics that react particularly to UVC (as well as UV-A and UV-B) radiation. Polyester, on the other hand, is much more resistant to UV light.
The effects of UVC radiation on material properties are similar to the influence of natural and direct sunlight over a longer period of time.
The short wavelengths of UVC radiation can cause plants to die.
We suggest that sensitive objects and plants are removed from rooms before UVC disinfection is carried out.
Most UVC tubes have an effective life expectancy of 9,000 hours.
Over the entire period of use of the UVC lamps, the amount of energy emitted drops slowly but steadily. After approx. 9,000 hours (the maximum effective service life), the radiation emitted reaches approx. 80% to 90% of the amount of energy of a new tube.
Yes, you can measure the UVC intensity either with a UVC paper indicator or a radiation meter.
UVC lamps contain toxic mercury. If a UVC tube breaks, switch off the corresponding unit immediately and pull out the mains plug. Open windows to ventilate the room for at least 30 minutes and wear nitrile gloves when handling the broken tube. Place the shards in a sealable plastic bag and follow local regulations when disposing of used bulbs. Do not use a hoover.
You should only use the types of tubes suggested in the relevant operating manual for the various products.
Broken or worn-out UVC tubes are hazardous waste and must be separated from normal waste and disposed of at designated hazardous waste collection points.
There is a lot of online literature and here are some links to it: