Very interesting thread Dor.
There is actually growing scientific evidence that a combination of UVA plus visible wavelengths does have a significant Germicidal effect. UV-C is one way to kill pathogens by breaking the DNA/RNA molecules, but UVA when accompanied by some violet wavelengths has a similar effect, albeit very much slower. However that is not necessarily a problem.
UV-C radiation is by far the fastest and most efficient method - but it has the drawback that it is dangerous to people, plants and animals and also causes excessive fading/embrittlement of polymeric materials, paints, furniture, inks etc. It also creates its own problems by breaking down organic materials into compounds which might be even more dangerous. The so-called sick building syndrome has in many cases been attributed to UV-C radiation in HVAC systems. Because of all of the above, UV-C must be concealed from view and/or only very brief exposures can be given.
UV-A is far less effective but has the huge advantage of not being dangerous. Exposure can be maintained continuously, even when people are present. During such long periods, significant germicidal effects become possible. Moreover, when combined with a photocatalytic material, the efficiency of UV-A systems can be very greatly amplified.
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« Last Edit: November 27, 2021, 02:34:46 PM by James »
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