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There is quite is quite a bit of information readily available about sterilizing disposable N95 masks with UV-C light. While not nearly as good as a fresh mask

There is quite is quite a bit of information readily available about sterilizing disposable N95 masks with UV-C light. While not nearly as good as a fresh mask, this might be a preferable alternative to reusing the same mask unsterilized. https://www.ajicjournal.org/article/S0196-6553(18)30140-8/pdf https://www.ajicjournal.org/article/S0196-6553(18)30140-8/pd... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699414/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699414/ https://www.peakprosperity.com/forum-topic/can-uv-light-disinfectant-box-kill-viruses-off-n95-mask/ https://www.peakprosperity.com/forum-topic/can-uv-light-disi... The UV light needs to have a wavelength around 260nm (shorter wavelength than standard UV light). Such UVC lamps are cheap and readily available, commonly used in consumer products for aquarium water sterilization and air purification. Example replacement bulb: GermGuardian LB4000 GENUINE UV-C Replacement Bulb for AC4300BPTCA, AC4825, AC4850PT & AC4900CA Germ Guardian Air Purifiers https://www.amazon.com/dp/B0055522F6/ref=cm_sw_r_cp_api_i_4DzCEbW8QFQ9V https://www.amazon.com/dp/B0055522F6/ref=cm_sw_r_cp_api_i_4D...

doodlebugging 7y ago
I believe that microwaving a used mask could also be an effective way to sterilize the mask. (0) I found this information by following links from the CDC website a few weeks ago when I was exploring the possibility of buying masks for my family and found that they were already being hawked online at ridiculous prices. Perhaps steam and/or use of a pressure cooker could also be effective. Many people who do home canning of food goods have a pressure cooker and are already familiar with usage and cleaning. The article posted suggests that this could be a viable method of home decontamination of used masks if I read it right. I also found an article that touched on use of a steamer to accomplish similar results. I can't find that article right now but if I do I will post it for review. Microwaving alone, without adding water to generate the steam should kill most water-based organisms. The article I read stated that microwave times from 30 seconds to 5 minutes were used. I need to find that article... What does everyone else think? I'd be interested in hearing. (0) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078131/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078131/
- SirLuxuryYacht 7y ago
  This[0] article goes over recommendations for extended use, reuse, and risks. It also has a healthy list of references, some of which are by Fisher et al., the author of the paper you linked. Most masks have a metal tab bending over the bridge of the nose, as well as metal staples for the elastic bands, which would prevent you from microwaving. Cartridge type filters would work though. [0]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3373043/#!po=12.5000 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3373043/#!po=12...
  - doodlebugging 7y ago
    I had considered the metal parts of the mask to be a potential problem. In the worst case scenario it should be relatively simple for mask owners to remove the metal tab from the nose and the staples holding the elastic bands before microwaving. Once they are done in the microwave the bands could be stapled in place with your ordinary stapler and the band reattached with hot glue. Those who have a needle and thread could also stitch a sleeve onto the nose piece that is open at one end and just reinsert the metal nose piece once it is out of the microwave. The thin metal should withstand several bend cycles before needing to be replaced and it can be replaced with any thin aluminum strip which one could obtain from lots of places around the house or at the hardware store. The bands and straps could be washed in ordinary soap to sterilize them before reuse. Just thinking outside the box here. What do you think?
    - mattkrause 7y ago
      You probably want to avoid manipulating the mask a lot, both because it may be contaminated and to avoid punctures.
      - doodlebugging 7y ago
        I agree that the mask could be contaminated. In fact, I would hope that the person wearing the mask has a good reason to wear it, either someone in their household is sick and they are protecting themselves or they are sick and they are protecting everyone else who is home with them. I think it is a bad idea for everyone to wear a mask when there is no threat to their health. With people furloughed home it is likely that many of us can avoid contact with an infected person and therefore we don't need masks. But if the user has paid close enough attention these last few weeks, then they are probably already washing hands anyway so as long as they wash up after putting the mask in the microwave and before they touch their face they should be good. If the mask is punctured that creates a much larger path for droplets to get behind the mask or if the user is the infected one, to get past the mask into the clean air on the other side. To mitigate that situation, there is no reason that I can see where coating the puncture with elmer's glue, hot glue, etc doesn't solve that issue. Bending the mask will probably create permeability that could allow larger particles to pass anyway. The plastic filaments they talk about are not likely to hold up to much flexing and it is a decrease in the tortuosity of the path through the media that creates the risk. Therefore, breakage along clearly defined planes creates an easy path through the media even if the mask is perfectly fitted to spec. I think bending the mask is the easiest way to send it out of spec so like you say, manipulating the mask creates a situation where it may no longer be effective against the particles sizes that it should protect against.
nerfhammer 7y ago
the thing is these masks were not designed to be re-used in a mechanical sense. they eventually just fall apart. they were meant to be thrown out after being used. still, one of them can last a few days in a pinch.
jennyyang 7y ago
We actually bought 2 UVC light bulbs just to sterilize my masks. We only have a handful, and believed early on that UVC could make them reusable, but have no proof. But using them is very hard. They produce ozone which is harmful to your lungs, and the light themselves are harmful to your eyes and skin. So I don't have a safe way to set this up yet. Now that we are all quarantined maybe we can have more time to figure out a sustainable way to use it.
- chuckledog 7y ago
  Browsing Amazon, it seems that there are some UVC bulbs that specifically avoid ozone creation. Other variants are marked “with ozone”, and for some reason both variants typically cost the same. I bought one “no ozone” and plan to put it in inside a reflective “pouch” (actually just a silver lined grocery carrier) for sterilizing things without exposing anything outside the bag to the UVC light.
- dillondoyle 7y ago
  I put mine on my back entrance which is basically open air. Close door with cord under it. Able to plug it in without being able to see it and ozone spews out to pollute my city even more.. Do you know how long of an exposure is needed to be effective? assuming within 2-3 feet but single source not even light
  - jennyyang 7y ago
    30 mins at 8 feet distance. 10 seconds if within an inch from what I remember.
- chuckledog 7y ago
  @jennyyang did you make your UVC setup yet? Here is what I wound up with over the weekend https://twitter.com/choser/status/1241933729536200709?s=21 https://twitter.com/choser/status/1241933729536200709?s=21 I also found the system a bit hazardous and am treating it with more respect now. It seems pretty powerful even at 13W. I was sterilizing my masks for 2 hours, now am just doing one minute per side.
DoingIsLearning 7y ago
Could the wavelength and power of these bulbs be used to sterilize daily objects used in public transport like mobile phones/wallets? Is there any guidance regarding duration of UVC radiation exposure and sterilization?
- javagram 7y ago
  There is a commercial product called Phone Soap (sold out now) that uses UV light to sterilize phones, keys, etc. you put the item inside it and I believe the UV light shines on it for 10 minutes which according to the manufacturer sterilizes it.
  - chuckledog 7y ago
    Yes and there is another commercial product that uses UV-C light to sterilize baby pacifiers: https://www.amazon.com/Munchkin-Portable-Sterilizer-Viruses-Bacteria/dp/B07ZPMKK7T/ref=sr_1_2?keywords=uv+baby+pacifier+cleaner&qid=1584591004&sr=8-2 https://www.amazon.com/Munchkin-Portable-Sterilizer-Viruses-...

doodlebugging 7y ago

I believe that microwaving a used mask could also be an effective way to sterilize the mask. (0) I found this information by following links from the CDC website a few weeks ago when I was exploring the possibility of buying masks for my family and found that they were already being hawked online at ridiculous prices. Perhaps steam and/or use of a pressure cooker could also be effective. Many people who do home canning of food goods have a pressure cooker and are already familiar with usage and cleaning. The article posted suggests that this could be a viable method of home decontamination of used masks if I read it right. I also found an article that touched on use of a steamer to accomplish similar results. I can't find that article right now but if I do I will post it for review. Microwaving alone, without adding water to generate the steam should kill most water-based organisms. The article I read stated that microwave times from 30 seconds to 5 minutes were used. I need to find that article... What does everyone else think? I'd be interested in hearing. (0) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078131/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078131/

SirLuxuryYacht 7y ago
This[0] article goes over recommendations for extended use, reuse, and risks. It also has a healthy list of references, some of which are by Fisher et al., the author of the paper you linked. Most masks have a metal tab bending over the bridge of the nose, as well as metal staples for the elastic bands, which would prevent you from microwaving. Cartridge type filters would work though. [0]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3373043/#!po=12.5000 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3373043/#!po=12...
- doodlebugging 7y ago
  I had considered the metal parts of the mask to be a potential problem. In the worst case scenario it should be relatively simple for mask owners to remove the metal tab from the nose and the staples holding the elastic bands before microwaving. Once they are done in the microwave the bands could be stapled in place with your ordinary stapler and the band reattached with hot glue. Those who have a needle and thread could also stitch a sleeve onto the nose piece that is open at one end and just reinsert the metal nose piece once it is out of the microwave. The thin metal should withstand several bend cycles before needing to be replaced and it can be replaced with any thin aluminum strip which one could obtain from lots of places around the house or at the hardware store. The bands and straps could be washed in ordinary soap to sterilize them before reuse. Just thinking outside the box here. What do you think?
  - mattkrause 7y ago
    You probably want to avoid manipulating the mask a lot, both because it may be contaminated and to avoid punctures.
    - doodlebugging 7y ago
      I agree that the mask could be contaminated. In fact, I would hope that the person wearing the mask has a good reason to wear it, either someone in their household is sick and they are protecting themselves or they are sick and they are protecting everyone else who is home with them. I think it is a bad idea for everyone to wear a mask when there is no threat to their health. With people furloughed home it is likely that many of us can avoid contact with an infected person and therefore we don't need masks. But if the user has paid close enough attention these last few weeks, then they are probably already washing hands anyway so as long as they wash up after putting the mask in the microwave and before they touch their face they should be good. If the mask is punctured that creates a much larger path for droplets to get behind the mask or if the user is the infected one, to get past the mask into the clean air on the other side. To mitigate that situation, there is no reason that I can see where coating the puncture with elmer's glue, hot glue, etc doesn't solve that issue. Bending the mask will probably create permeability that could allow larger particles to pass anyway. The plastic filaments they talk about are not likely to hold up to much flexing and it is a decrease in the tortuosity of the path through the media that creates the risk. Therefore, breakage along clearly defined planes creates an easy path through the media even if the mask is perfectly fitted to spec. I think bending the mask is the easiest way to send it out of spec so like you say, manipulating the mask creates a situation where it may no longer be effective against the particles sizes that it should protect against.

nerfhammer 7y ago

the thing is these masks were not designed to be re-used in a mechanical sense. they eventually just fall apart. they were meant to be thrown out after being used. still, one of them can last a few days in a pinch.

jennyyang 7y ago

We actually bought 2 UVC light bulbs just to sterilize my masks. We only have a handful, and believed early on that UVC could make them reusable, but have no proof. But using them is very hard. They produce ozone which is harmful to your lungs, and the light themselves are harmful to your eyes and skin. So I don't have a safe way to set this up yet. Now that we are all quarantined maybe we can have more time to figure out a sustainable way to use it.

chuckledog 7y ago
Browsing Amazon, it seems that there are some UVC bulbs that specifically avoid ozone creation. Other variants are marked “with ozone”, and for some reason both variants typically cost the same. I bought one “no ozone” and plan to put it in inside a reflective “pouch” (actually just a silver lined grocery carrier) for sterilizing things without exposing anything outside the bag to the UVC light.
dillondoyle 7y ago
I put mine on my back entrance which is basically open air. Close door with cord under it. Able to plug it in without being able to see it and ozone spews out to pollute my city even more.. Do you know how long of an exposure is needed to be effective? assuming within 2-3 feet but single source not even light
- jennyyang 7y ago
  30 mins at 8 feet distance. 10 seconds if within an inch from what I remember.
chuckledog 7y ago
@jennyyang did you make your UVC setup yet? Here is what I wound up with over the weekend https://twitter.com/choser/status/1241933729536200709?s=21 https://twitter.com/choser/status/1241933729536200709?s=21 I also found the system a bit hazardous and am treating it with more respect now. It seems pretty powerful even at 13W. I was sterilizing my masks for 2 hours, now am just doing one minute per side.

DoingIsLearning 7y ago

Could the wavelength and power of these bulbs be used to sterilize daily objects used in public transport like mobile phones/wallets? Is there any guidance regarding duration of UVC radiation exposure and sterilization?

javagram 7y ago
There is a commercial product called Phone Soap (sold out now) that uses UV light to sterilize phones, keys, etc. you put the item inside it and I believe the UV light shines on it for 10 minutes which according to the manufacturer sterilizes it.
- chuckledog 7y ago
  Yes and there is another commercial product that uses UV-C light to sterilize baby pacifiers: https://www.amazon.com/Munchkin-Portable-Sterilizer-Viruses-Bacteria/dp/B07ZPMKK7T/ref=sr_1_2?keywords=uv+baby+pacifier+cleaner&qid=1584591004&sr=8-2 https://www.amazon.com/Munchkin-Portable-Sterilizer-Viruses-...