Microorganisms are exposed to radiation from special and highly efficient low-pressure lamps that have a strong radiation peak at 254 nm (nanometres). This is not to be confused with the turquoise-blue light component often shown, which is also emitted by these emitters! The wavelength of 254 nm is very close to the absorption maximum of biological cells, which is around 260 nm. This radiation is absorbed in the cell nucleus of the organisms - more precisely in the DNA or RNA - resulting in a lasting photochemical change, so that the genetic material of the exposed cells is damaged. After sufficient exposure, the microbes are no longer able to repair the photochemical changes - this is referred to as dimerisation or dimer formation - cell division stops and they ultimately die.

In air disinfection, the air is passed past one or more UVC tubes in a central air duct or decentralised air recirculation system and thus disinfected. Wall and ceiling fittings with a single UVC tube are also commonly used, in which the air transport of germs is ensured via natural or technically induced convection. All forms of airborne microorganisms - i.e. bacteria, viruses, spores, mould and yeasts - are brought into the direct radiation range of the UV sources in one way or another and thus effectively and sustainably inactivated and killed. With a sufficient UVC dose, this happens within fractions of a second or, with a low UV radiation load, over time.

This means that the efficiency of an air disinfection process depends on the strength of the UVC radiation, the duration of exposure, the air speed, the humidity and ultimately also the type of microorganism. Because not every microorganism is the same. There are those that can only tolerate very little UVC radiation and those that are much more resistant. However, optimally designed UV systems can reliably and safely decimate all forms of airborne microbes.

Compared to alternative methods, UVC air sterilisation offers a whole range of advantages: It is very effective in killing or inactivating microorganisms such as bacteria, viruses, yeasts or other spore carriers, as the UVC radiation acts directly on their DNA or RNA and thus destroys them. In addition, mutations of microorganisms, e.g. the dreaded hospital germs such as MRSA (methicillin-resistant Staphylococcus aureus) or other antibiotic-resistant pathogens, play no role at all. The technique works solely by preventing cell division. And if this does not occur, no original or modified DNA information can be passed on. This distinguishes UVC air disinfection significantly from chemical disinfection methods.

In addition, UVC emitters do not add anything to the air or enrich it with anything that could cause allergic reactions or other health problems, for example. Because nothing is added to or taken away from the air, the technology can also be used in very sensitive areas such as the food industry. In principle, the possibilities for air disinfection are very limited here, as strict safety regulations apply and no biocides, gases or acids may be nebulised to improve air hygiene. However, a high level of air hygiene is essential to improve shelf life and product safety if the goods are to be protected from microbial spoilage.

UVC air sterilisation is an active method of air improvement that effectively decimates all forms of unwanted microbes 24/7 without any further supervision or requirements. It is extremely low-maintenance and reliable, provided there is no exceptional air pollution from grease, oil or cleaning agents. UVC air disinfection is highly effective, especially against small and microorganisms, i.e. bacteria and viruses. This means that UVC sterilisation is inversely proportional to the effectiveness of a filter system. This is because the finer the pore size of a filter system, the higher the pressure and energy loss. However, UVC low-pressure lamps in a ventilation system cause virtually no pressure loss at all. The UV lamps cannot become clogged either, which only increases the dynamic pressure. UVC systems are therefore often used in combination with high-quality filter systems, because there is one thing that UVC lamps cannot do: retain particles.

Finally, it should be mentioned that UVC air sterilisation is particularly energy-efficient and low-maintenance. Apart from the initial installation costs and the occasional replacement of the lamps, the running costs are very low.

Yes, UVC air sterilisation is absolutely safe for humans, provided the devices are installed and operated correctly. It's like using a kitchen knife: it's great for cutting vegetables, but you can also injure yourself if you handle it incorrectly. It is very similar with UVC systems: UV rays are absorbed by exposed cells and damage them. This is the defined goal, just as a knife must be as sharp as possible in order to cut tomatoes.

People should therefore never look into a luminous UVC source without protection, as UVC radiation can be harmful to the skin and eyes if it is powerful enough. Air sterilisation systems are therefore designed in such a way that the radiation remains in closed housings or air ducts so that no direct contact is possible. Open wall and ceiling units are usually connected downstream or have louvre blades in front of them. It is important that installation and maintenance are carried out by specialists. When used correctly, UVC air sterilisation poses absolutely no danger to humans or animals.

As a general rule, UVC radiation is very high-energy and short-wave, so it does not penetrate solid materials, solid clothing or normal panes of glass or acrylic glass. Even a large pair of safety goggles reliably protects the eyes.

In principle, a UVC air sterilisation system can be used wherever increased air hygiene is required. Whether in laboratories, storage or production, the areas of application are diverse. Today, the primary area of application is the food industry or the food production industry. This is because a high level of air hygiene helps to improve the shelf life and safety of food, as the risk of microbial contamination is significantly reduced. Especially in food production, air sterilisation systems have an immediate economic impact. Investment costs are amortised within a few months and there is less waste and downtime. UVC air disinfection systems can be used in processing rooms, packaging areas as well as in storage and maturing rooms. Such UV systems reliably reduce the spread of and contamination by yeasts, bacteria and mould spores everywhere in a 24/7 process.

UVC air disinfection is generally very effective and disinfection rates of 99.999 % are possible. This applies to laboratories, hospitals and other highly sensitive areas, but especially to the food industry. Not only are there special requirements in terms of hygiene during production and storage, but this is also where UVC systems really come into their own. By destroying the DNA or RNA in the microorganisms, UVC radiation specifically prevents them from multiplying and spreading in highly sensitive areas. Once listeria or mould have established themselves in a production or storage facility, the financial damage is considerable. UVC systems can prevent and actively combat this. In addition, the significant improvement in air quality in production and storage areas helps to minimise the risk of contamination. This increases the shelf life and safety of food, while ensuring compliance with strict hygiene and safety standards.

This can be answered very briefly and succinctly with NO. For marketing reasons, UVC LEDs are often advertised today with the characteristics of LEDs from the lighting industry, but this is misleading and usually false. The most powerful high-power LEDs today initially generate around 100 mW_uvc @ 350 mA under laboratory conditions and have an energy efficiency of approx. 5 %. In comparison, a conventional UVC low-pressure lamp achieves 18,000 mW_uvc @ 225 mA under the same conditions and has an energy efficiency of 40 %.

The reason for the low yield is the semiconductor material aluminium gallium nitride (AlGaN), which is required for very high frequencies, a typical reverse voltage of ~7 V for LEDs and the high heat development of up to 90° C. The mandatory cooling of such high-power LEDs prevents the formation of high-density LED arrays; homogeneous irradiation of high-intensity surfaces is therefore not possible. In addition, the higher the temperature of an LED, the shorter the expected service life/useful life. Very short-wave LEDs with 260 nm, for example, exhibit a power loss of up to 50 % after just 300 operating hours. In other words: the shorter the wavelength, the worse the energy balance, performance and service life!

Considering the poor recyclability of LEDs, which use materials such as antimony, arsenic, chromium, copper, gallium, gold, indium, iron, lead, nickel, phosphorus, silver and zinc, as well as the environmentally harmful mining of the rare earths required for their manufacture, such as europium (Eu), terbium (Tb) and yttrium (Y), the ecological advantages of LEDs, which are so readily claimed, quickly melt away.

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