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Even CDC site does not seem to mention uv as a method of sterilization.

  1. The only authoritative source of uv disinfection of COVID type virus I found was in 'https://www.ncbi.nlm.nih.gov/pubmed/14631830'. But it does not mention the most effective wavelength or a duration. Can somebody point me in the right direction?

  2. If 1 hour of appropriate UV exposure is sufficient to eradicate it, can head safety shields be reused after that period of time of exposure? I understand there might be limited # of cycles that polycarbonate shields can be reused, since the plastic will loose some transparency after repeated exposure.

  3. Can UV exposure be used for face respiration soft masks (N95 or plain) for disinfection?

If this has been covered here already - I'll remove.

EDIT1: Actually Franck's reference to Why aren't we sterilizing n95 masks? is relevant. Mark's answer does mention UV sterilization, but does not provide authoritative link/ref.

So, the other question of UV use for covid-19 sterilization of face shield is still open.

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From {1}:

[The SARS-CoV-2 virus virus] will be killed by UV, estimated survival in direct sunlight is 10% after 2–3h exposure

  • 90% of flu virus dies after 6h sunlight at spring equinox (3/21) at Bay Area latitude (Pubmed 17880524).
  • Coronaviruses are 2–3x more sensitive to UV than flu virus (Pubmed 16254359)

Regarding:

Can UV exposure be used for face respiration soft masks (N95 or plain) for disinfection?

See Why aren't we sterilizing n95 masks?


References:

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  • thank you, but in the n95 link there is no mention of UV sterilization. Also I guess part of the question is: will the UV get to and through the middle layer of the mask? What if UV exposure happens from both sides? i.e. 2 or more sources. – gene Mar 27 at 21:17
  • @gene search "UV" in the n95 link. – Franck Dernoncourt Mar 27 at 21:24
  • I was hoping somebody did a similar experiments on transparent shields and masks. Specifically for reuse of PPE. I understand the mask reuse maybe problematic, but I was hoping the UV on face shields might be a "no brainer". – gene Mar 27 at 21:31
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The inventor of the N95 filter material, Dr Peter Tsai, has said UV irradiation of the mask will destroy the electrostatic charge in the material rendering it much less effective. But then in this later interview he is less sure and says it needs to be tested as to whether the charge is affected.

https://utrf.tennessee.edu/information-faqs-performance-protection-sterilization-of-masks-against-covid-19/

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There are some reports suggesting that UVC light IS effective

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  • This addresses the kind of UV wavelength. But they tested it on the virus. I was hoping somebody did a similar experiments on transparent shields and masks. Specifically for reuse of PPE. – gene Mar 27 at 21:30
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    Your answer is composed of a link only. The trouble with link-only answers is that if the link ever goes bad, which happens frequently on the web, your answer becomes useless. Please quote the text in the link that you believe answers the question. – Carey Gregory Mar 28 at 15:59

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