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> I suspect that subjecting people indoors to an amount of UV radiation comparable with a day outside might be OK And I suspect this is very incorrect. UV is b

> I suspect that subjecting people indoors to an amount of UV radiation comparable with a day outside might be OK And I suspect this is very incorrect. UV is beneficial at low quantities, but has serious negative impacts on human health at high quantities.[1] Your mention of using it in common areas (where individuals would only be for a few minutes a day) seems much more reasonable. [1] https://en.wikipedia.org/wiki/Ultraviolet#Human_health-related_effects https://en.wikipedia.org/wiki/Ultraviolet#Human_health-relat...

XorNot 3y ago
The far UV spectrum being talked about here is not the same as conventional UVC germicidal lamps, nor the same as UVA/B from the sun. UV is only dangerous because at UVC wavelengths it penetrates cell nucleii and damages DNA. The interesting thing about far UV though is that while it will still damage DNA, it can't penetrate regular cells - it's blocked by the cell membrane/proteins. But viral particles don't have a cell membrane or a nucleus, so they have no protection against it. Basically, far UV can't damage cells, but can damage viruses.
- SECProto 3y ago
  > The far UV spectrum being talked about here is not the same as conventional UVC germicidal lamps, nor the same as UVA/B from the sun. I was responding to someone suggesting outside-levels of UV exposure. If we're talking about a different wavelength, I am even more doubtful of the safety.
- byb 3y ago
  Personally I feel the use of the term "far uv" is very misleading because the 220 nm wavelength is within UVC, and not too far away from 254 nm germicidal UVC. It is always helpful to consult a chart: http://www.drb-mattech.co.uk/uv%20spectrum.html http://www.drb-mattech.co.uk/uv%20spectrum.html So, from a public health/public education standpoint, I find it troubling that scientific research, which the article points out, is limited in this area. For decades, general advice has been that all UVC is dangerous to all life. We don't know below which wavelength does UVC no longer become harmful to animal (human) cells. Nor do we know if 220 nm wavelength light damage/weaken other materials. I'm not a chemist/engineer so I don't know if theoretical calculations can be made or if a massive scientific effort needs to be done to verify the impact of 220 nm UV light on lots of materials/life. If there is an animal/human cell safety region, perhaps a rebranding or subdivision of UVC into a "UV-D" is better than calling this "far uv". This has the added benefit of the "D" meaning "Death to germs/viruses". YouTuber Big Clive has had several videos on UVC lamps, I'd like to see someone get a 220 nm light into his hands to see if he smells like burnt meat. https://youtube.com/watch?v=1m0TQjBRcFo https://youtube.com/watch?v=1m0TQjBRcFo https://youtu.be/6DlfLthx89E?si=V4FD0DO4l09w2Wlr https://youtu.be/6DlfLthx89E?si=V4FD0DO4l09w2Wlr Edit: maybe I am a bit alarmist, some comments did share additional information about products offering this technology... I still hold that the branding/messaging is a problem by lumping it all together
  - bsder 3y ago
    As I understand it, the point of 222nm is NOT to sterilize organic tissue directly. The point of 222nm is to able to use it for sterilization in things like air return ducts, industrial cleaning equipment, etc. Since 222nm is relatively "safe", you don't have to worry some idiot opening up a system, giving himself a gigantic flux of UV in the face, and winding up in the ER for cornea burns. Consequently, your maintenance people don't need special equipment or extra training.
    - byb 3y ago
      This is the point of mechanical/electrical interlocks to prevent exposure to energized UVC. This is why I find the attempt to make 'far uv' safe in the public conscious even more dangerous.

XorNot 3y ago

The far UV spectrum being talked about here is not the same as conventional UVC germicidal lamps, nor the same as UVA/B from the sun. UV is only dangerous because at UVC wavelengths it penetrates cell nucleii and damages DNA. The interesting thing about far UV though is that while it will still damage DNA, it can't penetrate regular cells - it's blocked by the cell membrane/proteins. But viral particles don't have a cell membrane or a nucleus, so they have no protection against it. Basically, far UV can't damage cells, but can damage viruses.

SECProto 3y ago
> The far UV spectrum being talked about here is not the same as conventional UVC germicidal lamps, nor the same as UVA/B from the sun. I was responding to someone suggesting outside-levels of UV exposure. If we're talking about a different wavelength, I am even more doubtful of the safety.
byb 3y ago
Personally I feel the use of the term "far uv" is very misleading because the 220 nm wavelength is within UVC, and not too far away from 254 nm germicidal UVC. It is always helpful to consult a chart: http://www.drb-mattech.co.uk/uv%20spectrum.html http://www.drb-mattech.co.uk/uv%20spectrum.html So, from a public health/public education standpoint, I find it troubling that scientific research, which the article points out, is limited in this area. For decades, general advice has been that all UVC is dangerous to all life. We don't know below which wavelength does UVC no longer become harmful to animal (human) cells. Nor do we know if 220 nm wavelength light damage/weaken other materials. I'm not a chemist/engineer so I don't know if theoretical calculations can be made or if a massive scientific effort needs to be done to verify the impact of 220 nm UV light on lots of materials/life. If there is an animal/human cell safety region, perhaps a rebranding or subdivision of UVC into a "UV-D" is better than calling this "far uv". This has the added benefit of the "D" meaning "Death to germs/viruses". YouTuber Big Clive has had several videos on UVC lamps, I'd like to see someone get a 220 nm light into his hands to see if he smells like burnt meat. https://youtube.com/watch?v=1m0TQjBRcFo https://youtube.com/watch?v=1m0TQjBRcFo https://youtu.be/6DlfLthx89E?si=V4FD0DO4l09w2Wlr https://youtu.be/6DlfLthx89E?si=V4FD0DO4l09w2Wlr Edit: maybe I am a bit alarmist, some comments did share additional information about products offering this technology... I still hold that the branding/messaging is a problem by lumping it all together
- bsder 3y ago
  As I understand it, the point of 222nm is NOT to sterilize organic tissue directly. The point of 222nm is to able to use it for sterilization in things like air return ducts, industrial cleaning equipment, etc. Since 222nm is relatively "safe", you don't have to worry some idiot opening up a system, giving himself a gigantic flux of UV in the face, and winding up in the ER for cornea burns. Consequently, your maintenance people don't need special equipment or extra training.
  - byb 3y ago
    This is the point of mechanical/electrical interlocks to prevent exposure to energized UVC. This is why I find the attempt to make 'far uv' safe in the public conscious even more dangerous.