Electronics > Projects, Designs, and Technical Stuff
COVID-19 Emergency - Using UV Lamps to sanitize Face Masks overnight
viperidae:
--- Quote from: Buriedcode on March 17, 2020, 09:51:36 pm ---I'm not sure I've seen it mentioned here, but 70% isopropyl alcohol (rubbing alcohol) is more effective at disinfection than 80%+. Although I vaguely remember this being the case for bacteria, unsure about viruses.
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I heard it has something to do with the combination of water and alcohol that helps dissolve it. I think Dave said it on his recent hand sanitizer video
Buriedcode:
--- Quote from: Mechatrommer on March 17, 2020, 10:31:11 pm ---i find its funny when somebody or WHO? suggested that UV lamp should not be around bare skin. people go to beach to get sun tan. baby will get uv lamp treatment if found jaundice (or what?) darker people (which indicates more exposure to UV) are usually much resilient and stronger. and just yesterday, i fixed our front gate due to broken retainer by welding it again and now i have skin rash, tomorrow i expect some dead skin peeling off.. for countless number of time already... free sterilization in the process i guess, and new skin too.. my uv lamp (nail polish curer) that i used to cure solder mask or the uv lamp used in hospitals are nothing compared to that weld arc...
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I'm not sure what your point is but chronic over exposure to UV is a definite cancer risk. Acute UV burns have ionization damage. Regular UV burns are not just "oh well, it just toughens me up" - you are putting yourself at necessary risk.
Also you are confusing multiple UV sources with different bands and intensities. The sun, isn't quite the same as welding flash, isn't the same as UV sterilization lamps. These have different spectrums, intensities, and the shorter waves don't go far in air. The UV used to "cure" epoxy glue was likely 395-405nm at low intensity. That is a far cry from the ~200nm germicidal lamps (that are also a couple of orders of magnitude more intense).
Theraputic UV for skin conditions is carefully controlled, and won't be the short-wave type. You're effectively saying "this is light, and light is good right?".
LaserSteve:
If the bulb is germicidal, mercury filled, with the clear fused silica envelope and not the black light blue, it radiates 254 nm. It possibly has a modest but energetic line near 185 nm depending on doping in the quartz, and will create localized ozone in some small amount . I spent years working in a polymer fiber lab, making biofibers, and I assure you that all three do a nice job on surface virus and bacteria, given enough time. We would have used the lamp to sterilize thin layers as they go down, not the finished product.
The UV won't make it through to the core of the mask, but it will help break down most of the things that cause breath odors.
UVA, not so useful, UVB and UVC, will help.
A few one hour exposures will not harm the polymers very much, after all, one of the tests for the mask design should be degradation in sun light.
I cant endorse reusing masks, but for most polymer and natural fibers not a problem for a few modest irradiations. The afore mentioned quick splash of 66 to 70% alcohol will do far better for you, but the UV will also break down many of the organics that cause odors.
Any other solvent is a bad idea given that some fibrous materials are made with a solution deposition process. You do not want to remove any polymer binders that hold the fiber together.
Good filters are designed to collect pollutants not just at the surface, but to down to a certain depth of the filter material. Hence the reason I state UV helps, but it is not a cure.
My theory is anything is better then nothing, but you must have the right lamp. The lamp you want will quickly give you conjunctivitis, so you need an enclosure or polycarbonate goggles to protect your eyes. Nor do you want to breath in ozone.
If the virus is in a dried organic solution, it might take a very, very long time to kill the virus.
Better then nothing, but no where near 100% effective.
Remember, the surgical mask is designed to stop big droplets. Usually it is to prevent the wearer from infecting others, not to protect the wearer from airborne materials.
Steve
Mechatrommer:
--- Quote from: Buriedcode on March 17, 2020, 10:58:27 pm ---You're effectively saying "this is light, and light is good right?".
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i dont say we can keep exposed to UV all day long. i'm trying to say, its not that bad as its said. i usually find people who get rid of the said item entirely because of some warning from authority. people dont get into electronics because afraid of lead poisoning. who got mad or lost temper control due to life long soldering? people dont buy items from china or quarantine their arrived parcel for few days (after few days already in shipping) because extra fear to virus. people dont get into electronics afraid of get killed by mains elecricity. and many more examples i cant point them all now. the point is, these warning, without adequetely educate people on what kind of risk, made people extra taboo. UV probably can make skin cancer, but for how long exposure? 1 day? 10 days? or 1 year continuos exposure? most people will think 1 hour exposure (or even less like 1 minute exposure) and you'll get cancer. this people dont know we walked everyday under the sun without getting anything bad or short lived, we may get some benefit as well, sun produces all kind of spectrums. but i dont say we should lay under the sun all day long for no reason, just do what we have to do for our benefit, no need to raise extra taboo or fear.
KaneTW:
UVC is not something you should willingly expose yourself to, ever. It causes cataracts and skin damage at the intensities required to kill germs.
There's research indicating that 210nm UVC is safe, but a) I'm skeptical and b) 210nm lamps are quite expensive.
254nm UV (main mercury line) will damage you.
I'm worried about the material compatibility of FFP3/etc masks to solvents. UV definitely won't cut it for sanitizing them.
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