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I did asked before , but apparently providing a link to a science report of harmless for humans (both skin and eyes) far-UV light was not enough to make people understand the significance of the solution to the raging COVID-19. So this link (please read a bit of it): https://www.nature.com/articles/s41598-018-21058-w Says that the UV light of wavelength 222 nanometers (the photons bounces off the skin and the eyes) is absolutely harmless and do not make neither skin cancer or cataract. So this light is deadly for viruses and is not commercially available to anyone like ordinary humans (perhaps only some labs got it but sure cannot by on amazon or ebay or so). So if you wish to protect people you ideally need something to kill the virus in mid-air exactly as this lamp does. Cite: "By contrast, we have previously shown that far-UVC light (207–222 nm) efficiently inactivates bacteria without harm to exposed mammalian skin." - this line is at the beginning of the link above. So my idea is to help ordinary people that have some DIY experience to make a lamp and disinfect the clothes and themself like skin and face and face mask and so. So a guy good in chemistry of similar that ca help with his knowledge and experience to help the people and get rid of the virus. The research I did in the internet says that the UV has ability to kill virus in 10 seconds. So having a lamp emitting harmless 222nm UV light instead the cancer deadly 254nm UV germicidal lamps will be able to protect from the diseases. The question is how to make it.

so I suppose you can type a good way to do it and save the half of the western world population (the old people like your grandma and grandpa)?

(Nobody needs glass (or quartz) blowing of a lamp. Neither skills beyond the ordinary DIY - well it might be a need of experienced DIY-er.)

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  • $\begingroup$ Well I’ll be damned. 222 nm radiation doesn’t seem to affect humans. However, it would be immensely difficult (dare I say impossible) to DIY a lamp of 222 nm radiation. Getting that out of typical radiation sources (blackbody) would require insanely high temperatures. To do so through chemical means is beyond the ability of any DIY. $\endgroup$ – jezzo Mar 14 at 1:12
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    $\begingroup$ I find the claim that 222 nm radiation does not cause damage, just because it only penetrates the skin by a small, amount quite extraordinary. The energy is still absorbed and still has the ability to break bonds so how can it be safe? $\endgroup$ – porphyrin Mar 14 at 8:10
  • $\begingroup$ @porphyrin - because the top layer of skin cells are dead. So, if they absorb it all there is no harm. Just don’t scratch a lot... $\endgroup$ – Jon Custer Mar 14 at 16:42
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    $\begingroup$ The main problem is not making a lamp which emits at 222 nm. It is to be sure that this lamp does not also emit at 256 nm. $\endgroup$ – Maurice Mar 14 at 17:09
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    $\begingroup$ The paper claims that 222 nm UV does "not [...] penetrate through [...] the outer tear layer on the outer surface of the eye". That outer tear layer consists in good approximation of water. So what about viruses or microbes under a thin layer of water? $\endgroup$ – cbeleites unhappy with SX Mar 15 at 0:30
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UVC is very harmful to people and requires specialist equipment to create and use safely

You are not going to be able to create or use lamps that emit 222nM light without specialist equipment, and even if you could it would almost certainly not be safe.

Far UV lamps are widely commercially available for germicidal applications and these usually use mercury vapour fluorescent discharge tubes with no phosphors so have a strong emission around 250nM from a line in the mercury emission spectrum. They are very dangerous to people and have caused significant harm when used accidentally (see this video from BigClive describing what happens when they are used accidentally instead of the much less harmful "black light" tubes commonly used for discos and events).

Another important fact to bear in mind is that UVC lamps of this type have to use specialist glass in manufacture because common types of glass strongly absorb UVC wavelengths. So, while they are readily available, they are not easy for an amateur to make.

You report a claim from a Nature paper than a tightly controlled UVC light of around 222nM wavelength is not harmful to people. I would be far more cautious as the Nature paper did not do extensive safety studies on the actual effect on people and given what we know about wavelengths not much longer, the claim would need some extensive validation.

But you have bigger problems than this in your pursuit of an easy-to-make solution accessible to amateurs. First, you cannot easily get around the problem of the glass used absorbing the wavelengths you want to see: you will need specialist material. Second, the actual excimer lamps as used in the nature paper are sophisticated devices that cannot easily be made by non-specialists (they are far more complex than the relatively conventional discharge tubes used in commercial UV lamps which are essentially the same as conventional visible fluorescent lamps apart from the need for specialist glass). Apart from anything else the lamps have a strong emission at around 258nM, exactly the wavelength known to be very dangerous to people from simple UVC mercury vapour lamps. The NAture paper reported using specialist narrow band filters to eliminate those wavelengths. These are unlikely to be easy to obtain. Third, creating the excimer lamps is a sophisticated process requiring specialist pulsed electronic drivers to get the lamp to work (most likely, according to this reference in the Nature paper, you need to fine tune the gas mixture and the pressure and the driving electronics for the lamp which is far more complex than a simple driver for a fluorescent tube).

And, as for "Nobody needs glass (or quartz) blowing of a lamp", I'm afraid you are delusional. You need specialist glass to let the right wavelengths through and specialist filters to kill the harmful wavelengths. This is not "simple DIY".

You have seen an interesting paper in Nature and assumed it is easy for someone to make in their shed. This is not true. Specialist skills are required and attempting anything without those skills is likely highly dangerous (and that is ignoring the issues of handling the chemicals and vacuum technology needed to create the lamp: both are dangerous).

And, perhaps more importantly, the best way to avoid contamination of others with covid-19 is to wash your hands. There are no easy technological silver bullets here, though, perhaps, professional engineers and chemists can build something safe based on the Nature observation in the future.

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Interesting and per your cited source, to quote:

[...] far-UVC light generated by filtered excimer lamps emitting in the 207 to 222 nm wavelength range, efficiently inactivates drug-resistant bacteria, without apparent harm to exposed mammalian skin 13,14,15.

Also, more details:

Far-UVC lamps We used a bank of three excimer lamps containing a Kr-Cl gas mixture that predominantly emits at 222 nm 25,26. The exit window of each lamp was covered with a custom bandpass filter designed to remove all but the dominant emission wavelength as previously described 15. Each bandpass filter (Omega Optical, Brattleboro, VT) had a center wavelength of 222 nm and a full width at half maximum (FWHM) of 25 nm and enables >20% transmission at 222 nm.

This is a technical area and to be honest, this may not be the best forum on how to make a lamp with a Kr-Cl gas mixture with a custom bandpass filter.

I do get the feeling that they may be an associated patent application somewhere, that may provide more details. And, yes there is at least a patent pending upon performing a patent search. To quote from the company's website:

The New Columbia University Study again confirming the effectiveness and safety parameters of our patented wavelength (222nm) referred to by Columbia as Far-UVC.

These results confirm studies that we have been doing for the last 12 years. We have patented 222nm for air, liquid and surface disinfection.

Our patents cover all forms of skin and eye disinfection. We are in the process of getting FDA approval for a number of applications.

We call this wavelength Far-UV Sterilray.

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