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How Does UV-C Light Destroy Germs?

UV-C is part of the electromagnetic spectrum, which spans from Infrared to X-Rays. It has been known for over 70 years that it kills germs (viruses, bacteria and moulds). It has a wavelength from 200nm to 280nm. UV-C is beyond the visible spectrum, and hence is invisible to humans. The light sources we use have an output that also falls into the visible range, and hence appear blue when switched on. Whilst UV-C is harmful to skin and eyes, air sterilisation units are completely safe to use when people are present, owing to the lamps being contained within the units.

UV-C kills viruses by breaking down the links in the RNA or DNA. There has never been a virus discovered, which is resistant to UV-C. During 2020, however, studies have not only shown that the SARS-CoV-2 virus, which is responsible for Covid-19, is killed by UV-C, but we also know how much energy is required to do so. We are therefore able to design products and solutions to ensure airborne and surface viruses are killed as effectively as practically possible.

One of the most efficient ways to generate enough UV-C radiation is to use a conventional glass lamp. On average, 35% of input power is converted to UV-C power. The radiation generated is almost exclusively at 254nm viz. at 85% of the maximum germicidal effect and 80% on the IES curve. Unlike with general lighting, the technology behind LED UV-C lighting is not efficient. Only between 3% and 5% of the input power is converted to UV-C; hence much more energy is required to generate the same amount of UV-C with LED than a conventional glass TUV lamp.

We use high quality lamps. Lower cost lamps generate radiation wavelengths below 240nm and form ozone (O3) from oxygen in the air. This is highly reactive and toxic to humans, so precautions must be taken to avoid exposure to both life and certain materials.

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