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I have ordered a 15 W Chinese E27 UVC (200-275 nm) lamp from Amazon, and a E27 to wall socket plug with remote control. I am going to place it in the quarantine

I have ordered a 15 W Chinese E27 UVC (200-275 nm) lamp from Amazon, and a E27 to wall socket plug with remote control. I am going to place it in the quarantine zone downstairs to zap incoming mail and packages, just for any case. In one SARS-CoV study [1] the authors have irradiated SARS-CoV with a 254 and 365 nm UVC-UVA light source that emitted 4016 μW/cm^2. They found that "exposure of virus to UVC light resulted in partial inactivation at 1 min with increasing efficiency up to 6 min (Fig. 1A), resulting in a 400-fold decrease in infectious virus." If my math is correct, a 15 Watt UVC light bulb will provide 4.77 W/m^2 flux within the radius of 0.5 m - assuming it emits omnidirectionally. Assuming the delivered power versus inactivation efficiency relationship is linear, it would require roughly about an hour of zapping to achieve the same levels of inactivation with a 15 W lamp. Yes, we don't know if SARS-CoV inactivation times are comparable to that of COVID-19, but it's better than nothing. I am not a biologist, and micrographs of both viruses look somewhat similar. I wonder if they are structurally similar, should we expect similar susceptibility to incoming UV photons? [1] https://medtradex.com/assets/Uploads/Literature-UVD-Corona.pdf https://medtradex.com/assets/Uploads/Literature-UVD-Corona.p...

lvturner 7y ago
Would you mind linking to the light you bought? Or a comparable one l.
- blackhaz 7y ago
  Here is the one. I don't know if it performs in spec. Never bought one before. https://www.amazon.co.uk/gp/product/B085HZK755/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 https://www.amazon.co.uk/gp/product/B085HZK755/ref=ppx_yo_dt...
  - walterbell 7y ago
    Because this is (a) NOT Far-UVC, and (b) 360-degree light that shines in all directions, the only way to use it safely is with a remote power switch or a short timer so you (and pets) can get out of the room before the light turns on. Don't re-enter the room until the light is switched off remotely or with a timer. It is hazardous to your eyes and skin. Could it be used in a spotlight lamp that directs all the light in one direction?
    - jennyyang 7y ago
      I mention below I place the light bulb (using a hand-held socket) in a glass aquarium. Glass completely blocks UV-C light. The other hazard is ozone, so I use this outdoors on my patio or garage.
      - nerfhammer 7y ago
        > Glass completely blocks UV-C light. Erm, then why do they come in glass tubes like florescent lights?
        augustt 7y ago
        Not all glass is the same. Pure silica glass will pass UV, the soda-lime glass your windows are made of won't.
        jennyyang 7y ago
        I specifically said UV-C light. Do a bit of research and you'll find the answer.
    - blackhaz 7y ago
      Yeah, I got a E27 socket wall plug with wireless control. I assume it should be possible to get a remotely controlled lamp with reflector to make a spotlight out of it.
  - jennyyang 7y ago
    I bought a cheap glass aquarium for my UVC light bulb. Glass block UVC light completely so it becomes safe to use that for smaller items. Also you will produce a lot of ozone, so do this outdoors with a lot of ventilation.
- bikenaga 7y ago
  This is a 3-watt handheld - the power may be too low. https://www.amazon.com/Foldable-Travel-Household-Wardrobe-Toilet/dp/B075N1HTFZ/ref=sr_1_3?dchild=1&keywords=germise&qid=1585434717&sr=8-3 https://www.amazon.com/Foldable-Travel-Household-Wardrobe-To...
jennyyang 7y ago
One thing to note is that in your calculations, you are using 50cm distance, but in the study you linked, they are using 3 cm distance. Since this is inverse square law, that makes sense it would take longer to deactivate. For another point of reference, this study[1] says it takes 1.8 J/cm^2 to deactivate the flu virus. I'm not sure which is more hearty but from my calculations, it seems as though it's similar (about 2 J/cm^2). If that's the case then if you brought the intensity of your light up (bring the bulb much closer and possibly wrap it in material that reflects UV-C if that's even possible) then it would only take seconds to deactivate the virus. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699414/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699414/
- blackhaz 7y ago
  As far as I understand, we are talking about flux - per area at specified distance, not luminosity. I did recalculate flux for 0.5 m.
  - jennyyang 7y ago
    No. The study I referenced used total energy per cm^2 required to deactivate the flu virus, which is J/cm^2. You get that by multiplying the flux by the exposure time. So whichever exposure time gets you the 1.8 J/cm^2 is enough to kill the flu virus and presumably SARS-CoV-2.
    - blackhaz 7y ago
      Well, like I said - I recalculated for the flux of the 15 W lamp. An hour of zapping gets you to 1.72 J/cm^2 which is very close to your 1.8 J/cm^2 figure.
      - jennyyang 7y ago
        We are not disagreeing here, I think your 60 min calculation is correct. My point is that your calculations are at 50 cm and you get a much lower time for exposure if you bring your light bulb much closer and figure out a way to reflect the UV light so that more light from the bulb hits the intended target.
dillonmckay 7y ago
Make sure you wear longsleeve clothes and sunglasses, so you do not burn your skin or eyes!
- godelski 7y ago
  This needs to be up higher. I'm frequently concerned with people that read articles like these and do not understand safety precautions. The light the gp bought here will damage skin and eyes.

lvturner 7y ago

Would you mind linking to the light you bought? Or a comparable one l.

blackhaz 7y ago
Here is the one. I don't know if it performs in spec. Never bought one before. https://www.amazon.co.uk/gp/product/B085HZK755/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 https://www.amazon.co.uk/gp/product/B085HZK755/ref=ppx_yo_dt...
- walterbell 7y ago
  Because this is (a) NOT Far-UVC, and (b) 360-degree light that shines in all directions, the only way to use it safely is with a remote power switch or a short timer so you (and pets) can get out of the room before the light turns on. Don't re-enter the room until the light is switched off remotely or with a timer. It is hazardous to your eyes and skin. Could it be used in a spotlight lamp that directs all the light in one direction?
  - jennyyang 7y ago
    I mention below I place the light bulb (using a hand-held socket) in a glass aquarium. Glass completely blocks UV-C light. The other hazard is ozone, so I use this outdoors on my patio or garage.
    - nerfhammer 7y ago
      > Glass completely blocks UV-C light. Erm, then why do they come in glass tubes like florescent lights?
      - augustt 7y ago
        Not all glass is the same. Pure silica glass will pass UV, the soda-lime glass your windows are made of won't.
      - jennyyang 7y ago
        I specifically said UV-C light. Do a bit of research and you'll find the answer.
  - blackhaz 7y ago
    Yeah, I got a E27 socket wall plug with wireless control. I assume it should be possible to get a remotely controlled lamp with reflector to make a spotlight out of it.
- jennyyang 7y ago
  I bought a cheap glass aquarium for my UVC light bulb. Glass block UVC light completely so it becomes safe to use that for smaller items. Also you will produce a lot of ozone, so do this outdoors with a lot of ventilation.
bikenaga 7y ago
This is a 3-watt handheld - the power may be too low. https://www.amazon.com/Foldable-Travel-Household-Wardrobe-Toilet/dp/B075N1HTFZ/ref=sr_1_3?dchild=1&keywords=germise&qid=1585434717&sr=8-3 https://www.amazon.com/Foldable-Travel-Household-Wardrobe-To...

jennyyang 7y ago

One thing to note is that in your calculations, you are using 50cm distance, but in the study you linked, they are using 3 cm distance. Since this is inverse square law, that makes sense it would take longer to deactivate. For another point of reference, this study[1] says it takes 1.8 J/cm^2 to deactivate the flu virus. I'm not sure which is more hearty but from my calculations, it seems as though it's similar (about 2 J/cm^2). If that's the case then if you brought the intensity of your light up (bring the bulb much closer and possibly wrap it in material that reflects UV-C if that's even possible) then it would only take seconds to deactivate the virus. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699414/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699414/

blackhaz 7y ago
As far as I understand, we are talking about flux - per area at specified distance, not luminosity. I did recalculate flux for 0.5 m.
- jennyyang 7y ago
  No. The study I referenced used total energy per cm^2 required to deactivate the flu virus, which is J/cm^2. You get that by multiplying the flux by the exposure time. So whichever exposure time gets you the 1.8 J/cm^2 is enough to kill the flu virus and presumably SARS-CoV-2.
  - blackhaz 7y ago
    Well, like I said - I recalculated for the flux of the 15 W lamp. An hour of zapping gets you to 1.72 J/cm^2 which is very close to your 1.8 J/cm^2 figure.
    - jennyyang 7y ago
      We are not disagreeing here, I think your 60 min calculation is correct. My point is that your calculations are at 50 cm and you get a much lower time for exposure if you bring your light bulb much closer and figure out a way to reflect the UV light so that more light from the bulb hits the intended target.

dillonmckay 7y ago

Make sure you wear longsleeve clothes and sunglasses, so you do not burn your skin or eyes!

godelski 7y ago
This needs to be up higher. I'm frequently concerned with people that read articles like these and do not understand safety precautions. The light the gp bought here will damage skin and eyes.