4 ms·

Leaving UVC sources exposed to eyesight is completely irresponsible. Please don't do this.

toomuchtodo 9mo ago
Far-UVC and Eye Safety: Findings from a 36-Month Study - https://uvmedico.com/news/far-uvc-and-eye-safety https://uvmedico.com/news/far-uvc-and-eye-safety - January 16th, 2025 > Far-UVC is a type of ultraviolet light emitted at a 222 nm wavelength that effectively deactivates microorganisms. Unlike traditional UVC light at 254 nm, Far-UVC doesn’t penetrate the outer dead layer of skin or the outer layer of the cornea, making it safe for use around people while maintaining powerful germicidal properties. > The 222 nm wavelength is unique in its ability to decontaminate without causing harm when used within regulatory limits. Unlike longer UV wavelengths, it interacts only with the outermost layers of the skin and eyes, which naturally renew themselves. This makes it ideal for continuous decontamination in occupied spaces, as confirmed by the 36-month clinical study showing no adverse effects even after daily exposure. References: https://www.faruvc.org/ https://www.faruvc.org/ (disclosure: this is published by the same author as this post) Sugihara K, Kaidzu S, Sasaki M, Ichioka S, Sano I, Hara K, Tanito M. Ocular safety of 222-nm far-ultraviolet-c full-room germicidal irradiation: A 36-month clinical observation. Photochem Photobiol. 2024 Dec 10. https://doi.org/10.1111/php.14052 https://doi.org/10.1111/php.14052 Epub ahead of print. PMID: 39659140. https://onlinelibrary.wiley.com/doi/10.1111/php.14052 https://onlinelibrary.wiley.com/doi/10.1111/php.14052 Sugihara K, Kaidzu S, Sasaki M, Tanito M. Interventional human ocular safety experiments for 222-nm far-ultraviolet-C lamp irradiation. Photochem Photobiol. 2024 Aug 19. https://doi.org/10.1111/php.14016 https://doi.org/10.1111/php.14016 Epub ahead of print. PMID: 39161063. https://onlinelibrary.wiley.com/doi/10.1111/php.14016 https://onlinelibrary.wiley.com/doi/10.1111/php.14016 Buonanno M, Hashmi R, Petersen CE, Tang Z, Welch D, Shuryak I, Brenner DJ. Wavelength-dependent DNA damage induced by single wavelengths of UV-C radiation (215 to 255 nm) in a human cornea model. Sci Rep. 2025 Jan 2;15(1):252. https://doi.org/10.1038/s41598-024-84196-4 https://doi.org/10.1038/s41598-024-84196-4 PMID: 39747969; PMCID: PMC11696903. https://www.nature.com/articles/s41598-024-84196-4 https://www.nature.com/articles/s41598-024-84196-4
- roywiggins 9mo ago
  I think that blog post is mostly just an AI summary of one or more of those studies.
  - toomuchtodo 9mo ago
    Noted, it was included for completeness after I had independently found the resources I enumerate.
- modeless 9mo ago
  Interesting study. Only four people though, and the lamps were "carefully calibrated" so exposure was within a safety threshold. I've seen some lamps have safety interlocks that attempt to turn off the light if people get too close. I don't think UVC will be practical for most settings as long as it needs this kind of caution. If we could establish a higher safety threshold so that we could be sure it wouldn't harm humans even if they were very close to the lamp, that would be great. Then we could deploy it in almost any public or private space.
- daveguy 9mo ago
  FYI, all three of the studies are funded by UV light manufacturers: Ushio Inc (first two, 100%), and LumenLabs (last one, partially).
  - Nukit 9mo ago
    [dead]
jefftk 9mo ago
(author) This absolutely depends on the frequency of UVC and the intensity of the lamp. The lamps this post links such as https://aerolamp.net https://aerolamp.net are putting out 222-nm, which is much safer than longer UVC wavelengths and the intensity is well under TLV when placed 8.5ft up (or higher). See https://www.faruvc.org https://www.faruvc.org for more on eye safety.
- the8472 9mo ago
  Ah nice, their data sheet has a spectrum. Kind of odd that they don't market the "we filter out the harmful parts" feature more prominently.
  - Nukit 9mo ago
    Many manufacturers refuse to post third party spectral assays detailing safety and power output, it's a big problem.
  - vbelenky 9mo ago
    Kinda like advertising "Asbestos-Free Cereal" isn't it? If someone was marketing a product to me and they were super insistent about how super duper safe it was I would probably start getting suspicious
    - the8472 9mo ago
      UV rightfully raises concerns about skin damage, highlighting that they're careful about excluding the harmful parts would be helpful for customers who either know just enough to think "UV bad" or to those who wonder how narrow their filters are. Imo a better analogy would be selling a circular saw with a safety mechanism and hiding the latter in the specsheet.
    - gs17 9mo ago
      No, it's more like advertising asbestos-free talc.
- trashface 9mo ago
IAmBroom 9mo ago
You are not an expert on optical safety and should not make sweeping, generalized statements as though you were. I am an optical engineer, but don't specialize in eye-safe studies, and I wouldn't dare make a statement without consulting safety guidelines. The eye's sensitivity to wavelengths is exponentially variable, and very specific about some cutoffs - moreso than most biological phenomena, because the limiting factors are bandgaps of molecules, not cell structures.
- Retz4o4 9mo ago
  https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/
  - IAmBroom 9mo ago
    Retz, I was replying to the same post you were. You were not the problem.
Retz4o4 9mo ago
This is not UVC - this is Far UVC and is blocked by the outer layer of your eyeball, so it is safe. https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/

Far-UVC and Eye Safety: Findings from a 36-Month Study - https://uvmedico.com/news/far-uvc-and-eye-safety https://uvmedico.com/news/far-uvc-and-eye-safety - January 16th, 2025 > Far-UVC is a type of ultraviolet light emitted at a 222 nm wavelength that effectively deactivates microorganisms. Unlike traditional UVC light at 254 nm, Far-UVC doesn’t penetrate the outer dead layer of skin or the outer layer of the cornea, making it safe for use around people while maintaining powerful germicidal properties. > The 222 nm wavelength is unique in its ability to decontaminate without causing harm when used within regulatory limits. Unlike longer UV wavelengths, it interacts only with the outermost layers of the skin and eyes, which naturally renew themselves. This makes it ideal for continuous decontamination in occupied spaces, as confirmed by the 36-month clinical study showing no adverse effects even after daily exposure. References: https://www.faruvc.org/ https://www.faruvc.org/ (disclosure: this is published by the same author as this post) Sugihara K, Kaidzu S, Sasaki M, Ichioka S, Sano I, Hara K, Tanito M. Ocular safety of 222-nm far-ultraviolet-c full-room germicidal irradiation: A 36-month clinical observation. Photochem Photobiol. 2024 Dec 10. https://doi.org/10.1111/php.14052 https://doi.org/10.1111/php.14052 Epub ahead of print. PMID: 39659140. https://onlinelibrary.wiley.com/doi/10.1111/php.14052 https://onlinelibrary.wiley.com/doi/10.1111/php.14052 Sugihara K, Kaidzu S, Sasaki M, Tanito M. Interventional human ocular safety experiments for 222-nm far-ultraviolet-C lamp irradiation. Photochem Photobiol. 2024 Aug 19. https://doi.org/10.1111/php.14016 https://doi.org/10.1111/php.14016 Epub ahead of print. PMID: 39161063. https://onlinelibrary.wiley.com/doi/10.1111/php.14016 https://onlinelibrary.wiley.com/doi/10.1111/php.14016 Buonanno M, Hashmi R, Petersen CE, Tang Z, Welch D, Shuryak I, Brenner DJ. Wavelength-dependent DNA damage induced by single wavelengths of UV-C radiation (215 to 255 nm) in a human cornea model. Sci Rep. 2025 Jan 2;15(1):252. https://doi.org/10.1038/s41598-024-84196-4 https://doi.org/10.1038/s41598-024-84196-4 PMID: 39747969; PMCID: PMC11696903. https://www.nature.com/articles/s41598-024-84196-4 https://www.nature.com/articles/s41598-024-84196-4

roywiggins 9mo ago
I think that blog post is mostly just an AI summary of one or more of those studies.
- toomuchtodo 9mo ago
  Noted, it was included for completeness after I had independently found the resources I enumerate.
modeless 9mo ago
Interesting study. Only four people though, and the lamps were "carefully calibrated" so exposure was within a safety threshold. I've seen some lamps have safety interlocks that attempt to turn off the light if people get too close. I don't think UVC will be practical for most settings as long as it needs this kind of caution. If we could establish a higher safety threshold so that we could be sure it wouldn't harm humans even if they were very close to the lamp, that would be great. Then we could deploy it in almost any public or private space.
daveguy 9mo ago
FYI, all three of the studies are funded by UV light manufacturers: Ushio Inc (first two, 100%), and LumenLabs (last one, partially).
- Nukit 9mo ago
  [dead]

jefftk 9mo ago

(author) This absolutely depends on the frequency of UVC and the intensity of the lamp. The lamps this post links such as https://aerolamp.net https://aerolamp.net are putting out 222-nm, which is much safer than longer UVC wavelengths and the intensity is well under TLV when placed 8.5ft up (or higher). See https://www.faruvc.org https://www.faruvc.org for more on eye safety.

the8472 9mo ago
Ah nice, their data sheet has a spectrum. Kind of odd that they don't market the "we filter out the harmful parts" feature more prominently.
- Nukit 9mo ago
  Many manufacturers refuse to post third party spectral assays detailing safety and power output, it's a big problem.
- vbelenky 9mo ago
  Kinda like advertising "Asbestos-Free Cereal" isn't it? If someone was marketing a product to me and they were super insistent about how super duper safe it was I would probably start getting suspicious
  - the8472 9mo ago
    UV rightfully raises concerns about skin damage, highlighting that they're careful about excluding the harmful parts would be helpful for customers who either know just enough to think "UV bad" or to those who wonder how narrow their filters are. Imo a better analogy would be selling a circular saw with a safety mechanism and hiding the latter in the specsheet.
  - gs17 9mo ago
    No, it's more like advertising asbestos-free talc.
trashface 9mo ago

IAmBroom 9mo ago

You are not an expert on optical safety and should not make sweeping, generalized statements as though you were. I am an optical engineer, but don't specialize in eye-safe studies, and I wouldn't dare make a statement without consulting safety guidelines. The eye's sensitivity to wavelengths is exponentially variable, and very specific about some cutoffs - moreso than most biological phenomena, because the limiting factors are bandgaps of molecules, not cell structures.

Retz4o4 9mo ago
https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/
- IAmBroom 9mo ago
  Retz, I was replying to the same post you were. You were not the problem.

Retz4o4 9mo ago

This is not UVC - this is Far UVC and is blocked by the outer layer of your eyeball, so it is safe. https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/