UV-C 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. UV-C is located at the short-wave end of the spectrum and is invisible to the human eye. Although no visible light is emitted, it is still called "ultraviolet light".

One of the key properties of the UV-C spectral wavelength range is that this radiation energy, when placed within range of a surface, deactivates viruses, bacteria and mould spores. UVC is therefore called germicidal ultraviolet radiation (GUVI - "germicidal ultraviolet irradiation").

No, in fact, germicidal ultraviolet irradiation has been studied since the late 19th century, and with a focus on UV-C irradiation from around 1930. In 1935, scientists proved through various tests the ability of UV-C radiation to effectively deactivate microorganisms in the air. In the 1970s it was proven that UV-C radiation reduces tuberculosis infections. Since the early 1990s, a major focus of research and development has been on improving the efficiency and safety of UV-C products as a means of deactivating viruses and bacteria. The UV-C technology is a proven and useful tool for combating microorganisms.

Various scientific studies have proven a high effectiveness in reducing the number of dangerous microorganisms when the technology is applied according to manufacturer recommendations, e.g.: "The implementation of this "No-Touch" technology has led to a sustainable reduction of microbiological contamination of surfaces, reduced contamination transmission and the reduced spread of drug-resistant bacteriological infections in various hospitals. In the study by Liscynesky et al. [15], a total of 32 of 238 (13%) "high touch surfaces" in hospital rooms with proven contamination by C. difficile infection (CDI) pathogens tested positive after cleaning with disinfectants. Only 1 of the 238 (0.4%) surfaces tested positive after application of UV-C disinfection (the computer keyboard), after 3 compound emitters with 254nm wavelength were active for 45 min". Evaluation of a "High Touch Surface Disinfection" with an Ultraviolet C (UV-C) LED lamp in critical areas of hospitals, Beatrice Casini et al, September 24, 2019].

Germicidal ultraviolet irradiation has been shown to destroy or deactivate 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 UV-C radiation comes into contact with microorganisms, photochemical reactions are triggered while the radiation is absorbed. The DNA of the microorganism is then destroyed. In principle, the absorption of the photons prevents the DNA from replicating (multiplying).

Because Covid-19 is so new, there are still many test series that are currently being conducted worldwide. However, recent research at Columbia University in the USA has concluded that UV-C irradiation is an efficient method of fighting and eliminating the virus. Recent tests carried out at the Institute of Medical Virology at Frankfurt University Hospital after the outbreak of the corona pandemic also showed that irradiation of corona viruses with UV-C discharge lamps as well as UV-C LEDs resulted in a killing rate of up to 99.4 percent.The structure of the corona virus SARS-CoV-2 is very similar to the structure of other corona viruses, including MERS. There is no evidence that UV-C radiation should not be an effective disinfection method to combat Covid-19. It is proven that UV-C radiation is a very good method for deactivating viruses such as MERS or SARS, which are closely related to Covid-19.

UV products use low pressure (Hg) mercury discharge tubes. These tubes generate UV-C radiation at a wavelength of 253.7nm, which is currently the closest technically feasible range to the most effective range for deactivating microorganisms (260 to 265nm). Therefore, direct and indirect disinfection lamps are well suited for germicidal ultraviolet irradiation.

No, unlike other disinfection methods, such as chlorination etc., UV-C radiation does not produce any by-products, substances or other residues. According to a statement by Philips (UV-C tube manufacturer), for example, no residues of substances have been detected after UV-C disinfection.

Position your UV-C lamp in a way that it covers an area to be disinfected as well as possible. To do this, select the appropriate product with the appropriate performance class and set the appropriate time on the unit in relation to the surface to be disinfected on the UV-C lamp. Please make absolutely sure that the UV-C lamp stands securely on a firm base or is otherwise permanently installed. It must be ensured that areas within the surface to be disinfected that are covered by "object shadow" cannot be disinfected. We therefore always recommend the simultaneous use of several emitters, which act from different directions, for the disinfection of a surface in order to largely exclude shadows.

UV-C lamps are designed in such a way that, if they are optimally aligned to a surface to be disinfected and the corresponding disinfection time for the irradiation is preselected, 99.9% of the microorganisms present within the disinfection beam path can be killed or deactivated. However, it is recommended to combine the disinfection measure by UV-C irradiation with other disinfection methods in problem areas. For example, one or more UV-C 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.
Eine durch UV-C Strahlung zu desinfizierende Oberfläche sollte vor der Behandlung staubfrei sein, damit die UV-C Strahlung ungehindert auf die Oberfläche des zu behandelnden Objektes treffen kann.

There are very few examples of areas where all surface areas can be reached freely by rays from a single UV-C lamp. We therefore always recommend the use of several UV-C luminaires for a given room to be disinfected, which is then irradiated from different directions and angles to guarantee maximum and complete irradiation of all surfaces. Please note that we always recommend the combination of UV-C irradiation with other disinfection methods to achieve the best possible disinfection of a room.

This depends on the UV-C lamp model (which defines the emitted energy for the germicidal ultraviolet irradiation) and the selected time for the UV-C irradiation of the surface to be disinfected.

Incorrect use and improper installation can lead to UV-C products restricting safety. Always follow the instructions in the operating manual. UV-C technology has been scientifically researched and described extensively. In comparison to UV-A and UV-B radiation, both of which are components of the sunlight hitting the earth, UV-C radiation does not penetrate very deeply into the skin due to the scattering that increases with shorter wavelengths. UV-C radiation is absorbed in the upper, mostly dead layers of the human skin. The maximum daily radiation of 253.7 nm wavelength to which a person should be exposed is 6 mJ / cm² over a period of 8 hours [American Conference of Governmental Industrial Hygienists. 2020 Threshold Limit Values and Biological Exposure Indices]. This UV exposure is comparable to a 10-minute bath in direct sunlight with a UV index of 10. Nevertheless, UV-C radiation can cause temporary skin and eye irritation as well as redness. Long-term exposure to UV-C radiation can cause burns, so when operating ultraviolet disinfection lamps, there should NOT be people, animals or plants in the rooms to be disinfected. This is comparable to the change in material properties when these objects are exposed to direct sunlight. After the application of UV-C lamps for disinfection in closed rooms, the corresponding room must be ventilated for approx. 10 minutes. Several safety precautions are integrated in the UV-C disinfection lamps to largely exclude improper use and minimise the risk of injury.

NO. Humans and animals should not be in the same room when a UV-C direct radiator is activated. When handling UV-C radiation generating lamps, suitable safety glasses and nitrile gloves must be worn and opaque, close-meshed clothing must cover all areas of the skin. When replacing UV-C lamps, the lamp should always be disconnected from the power supply and the same safety precautions as above apply.

Almost 100% of the UV-C radiation is blocked by window glass. Window glass is made of different components. One of these components is cerium oxide: a compound that blocks UV-C radiation. The material used for the manufacture of UV-C tubes is quartz glass, which contains only one component of silicon dioxide. This allows UV-C radiation to pass through. For this reason, the radiation generated in the UV-C lamp can pass through the glass envelope, but not through a window. You can find further information here: https://www.iuva.org/UV-FAQs.

This depends on the nature and composition of the material. Some transparent plastics will allow UV-C radiation to pass through, while others will not. However, it should be mentioned 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 silicon dioxide is used for the production of lamp housings). From this it can be deduced that most transparent materials do not allow UV-C radiation to pass through, while opaque / frosted materials and tightly woven fabrics also have a blocking effect of UV-C radiation.

UV light has a fundamental ageing effect on certain materials such as paints, colours in fabrics or some plastics. Polypropylene (PP) and soft polyethylene are plastics that react especially to UV-C (as well as UV-A and UV-B) radiation. Polyester, for example, is much more resistant to UV light. The effects of UV-C radiation on material properties are similar to the effects of natural and direct sunlight over a longer period. The short wavelengths of UV-C radiation can cause plants to die. We suggest that sensitive objects and plants be removed from rooms before UV-C disinfection is carried out.

Most UV-C tubes have an effective lifetime of 9,000 hours.

Over the entire period of use of the UV-C lamps, the amount of energy emitted decreases slowly but steadily. After approx. 9,000 hours (the maximum effective service life) the emitted radiation reaches approx. 80% to 90% of the energy quantity of a new tube.

Yes, you can measure the UV-C intensity either with a UV-C paper indicator or a radiation meter.

To ensure maximum efficiency, we recommend periodically wiping the UV-C tubes with a slightly moistened, soft and clean cotton cloth to remove deposited dust.

UV-C lamps contain toxic mercury. If a UV-C tube should break, switch off the corresponding device 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 splitters in a sealable plastic bag and follow local regulations when disposing of used lamps. Do not use a vacuum cleaner.

You should only use the tube types that are suggested in the corresponding operating manual of the corresponding products.

Broken or worn-out UV-C 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:

https://media.ies.org/docs/standards/IES-CR-2-20-V1-6d.pdf

www.ncbi.nlm.nih.gov/pmc/articles/PMC3292282/

www.ncbi.nlm.nih.gov/pmc/articles/PMC6801766/

www.ncbi.nlm.nih.gov/pmc/articles/PMC2789813/

www.ies.org/standards/committee-reports/ies-committee-report- cr-2-20-faqs/

www.ies.org/standards/committee-reports/