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I have a question. Does anybody know why we keep our indoor light sources uva / uvb free ? I know that too much UVA/B light seems to be carciogenic, but a small

by pfyy 5y ago

I have a question. Does anybody know why we keep our indoor light sources uva / uvb free ? I know that too much UVA/B light seems to be carciogenic, but a small amount of it, especially UVB seems to be beneficial to human and still kills germs, especially covid [1] The positive effects are a) vitamin d production b) germicide The negative effects are c) lower energy efficiency in the visible spectrum (watt per visible light produced) d) negative effect on the eye e) carciogenic For indoor keeping of reptiles UVB light seems to be needed [2] As far as i've read, for indoor planting, UV light seems to beneficial as well, for example it increases the production of THC [3] Why should we, as humans, be different ? [1]Ratnesar-shumate, S.; Williams, G.; Green, B.; Krause, M.; Holland, B.; Wood, S.; Bohannon, J.; Boydston, J.; Freeburger, D.; Hooper, I.; Beck, K.; Yeager, J.; Altamura, L. A.; Biryukov, J.; Yolitz, J.; Schuit, M.; Wahl, V.; Hevey, M.; Dabisch, P. Simulated Sunlight Rapidly Inactivates SARS-CoV-2 on Surfaces. J. Infect. Dis. 2020, 222 (2), 214–222.Google Scholar https://sci-hub.st/https://doi.org/10.1093/infdis/jiaa274 https://sci-hub.st/https://doi.org/10.1093/infdis/jiaa274 [2] https://en.wikipedia.org/wiki/Ultraviolet#UVB https://en.wikipedia.org/wiki/Ultraviolet#UVB [3] https://vanessa-nielsen.com/cannabis-plants-uv-light/ https://vanessa-nielsen.com/cannabis-plants-uv-light/

weaksauce 5y ago
if i had to guess there are a few reasons they don't do this... the first and most important reason is manufacturers have and will optimize for the main benefit of a product. the main product here is light. heat came as a negative byproduct of traditional incandescent lights and heat is something to minimize to lengthen the life of an led bulb. another possibility is that if it were widespread it could cause some negative outcomes of people sitting too closely to a source of it and potentially exposing the companies to legal issues. not a lawyer and they might be able to shield themselves from that liability with well written disclaimers though. Along with inertia from the incandescent bulbs not emitting that wavelength... the most likely reason is that they don't want to spend the money on researching how safe it is and how to cost effectively make them like that though.
defaultname 5y ago
UV A/B is oxidizing, which is why plastics left outside degrade rapidly, discoloration occurs, etc. It's bad for your eyes, bad for your skin in excess, and creates ozone in the air which is an environmental pollutant. Normal indoor plants have no need for UV at all. Nor do most food plants -- greenhouse glass blocks UV, for instance.
collegeburner 5y ago
Because UV fades fabric, degrades plastic, damages and discolors wood, etc.
sega_sai 5y ago
I don't think germicide is necessarily good. There are theories that the abundance of allergies and autoimmune diseases is partially caused by excessive cleanliness/lack of exposure to microbes etc.
- scotty79 5y ago
  I think allergies and autoimmune diseases are partially caused by the fact that people are no longer work infested with parasites in yhe way they were all the time since forever. Parasites suppress immune responses. I think we should figure out how to substitute their influence on humans before we conclude that exposing ourselves to bacteria and viruses a lot is a good thing.
  - richardfey 5y ago
    Surely there must be some research on this?
briHass 5y ago
CFL bulbs, especially earlier versions often emitted a surprising amount of UV light. The speculation is that the tight coils of glass would result in breaks in the phosphor coating, letting the UV through. I know I have fixtures that used to have CFLs in them, and any plastic is yellowed significantly.
- bradknowles 5y ago
  UV in fluorescent bulbs escapes directly through the phosphor itself. No phosphor is 100 opaque to UV, nor does any phosphor convert 100% of UV to visible light. Some phosphor coatings might be better than others, but they will all leak a certain amount of UV.
peterburkimsher 5y ago
"kills germs, especially covid" There's some misinformation that claims to "kill COVID" (which is a symptom not a virus) so therefore the recommendation is to say "deactivates SARS-COV-2". Personally I've been trying to reach out to people with scanning electron microscopes, because there's a hypothesis that I'd like to test. VisualCapitalist have an infographic showing the size of particles, including coronaviruses as 0.1-0.5 microns. I'd assumed a Gaussian bell curve centred around 0.3 micron, but was kindly corrected here on HN that SARS-COV-2 is closer to 0.1 micron. My hypothesis is that UV-C light at 300 nm = 0.3 micron, or 100 nm = 0.1 micron, will cause the particles to resonate. In a less formal way, play them the right beat and make the virus dance itself to pieces. To that end, I bought some UV-C lamps (safely inside plastic boxes) from an aquarium shop. Air filters are all sold out in New Zealand, and suppliers are on holiday. The seller understood, but warned that it can cause sunburn within seconds, and eye damage - so don't look into the blue light! This makes sense because of the size of rod cells in the eye. Then I got a regular PC fan, and ran it overnight, blowing air through the light. It felt like the air became very dry, and increasingly unpleasant. Although it didn't smell "fresh", and the window was open for some ventilation, I'm a little worried about ozone production. Not sure how to test that though. Fabric filters in HVAC will work according to their feature size (like an N95 vs surgical mask), but the difficulty is remembering to change them. So personally I still think UV-C is the solution, I just don't know how to use it safely yet. Certainly it makes sense for disinfecting the mask recycling bins (biohazard infectious substances taken out of the environment = litter picked up) but for ambient air, I'm still learning how to do that safely.
- bradknowles 5y ago
  Use both UV and good quality HEPA filters, if you can. Heck, you can even get filters that greatly exceed the filtration capacity of HEPA filters, and get objects down to .01 microns, which is a tenth to a thirtieth of the size you’re projecting for the smaller particles. But they are expensive. If you’re interested, look at the IQAir brand.
  - peterburkimsher 5y ago
    There's some that were being thrown away at work during the office clear-out before the Christmas holiday, so I do have some filters! Today I went back and tidied up the boxes and found them. Need to figure out how to make an air-tight seal in a cardboard box though; I'm no expert at 3D printing real parts (and I'd need to book time on the Ultimaker or laser cutter).
ezconnect 5y ago
Everything age fast under UV lights so it's suggested to limit exposure to it.

by pfyy 5y ago

weaksauce 5y ago

if i had to guess there are a few reasons they don't do this... the first and most important reason is manufacturers have and will optimize for the main benefit of a product. the main product here is light. heat came as a negative byproduct of traditional incandescent lights and heat is something to minimize to lengthen the life of an led bulb. another possibility is that if it were widespread it could cause some negative outcomes of people sitting too closely to a source of it and potentially exposing the companies to legal issues. not a lawyer and they might be able to shield themselves from that liability with well written disclaimers though. Along with inertia from the incandescent bulbs not emitting that wavelength... the most likely reason is that they don't want to spend the money on researching how safe it is and how to cost effectively make them like that though.

defaultname 5y ago

UV A/B is oxidizing, which is why plastics left outside degrade rapidly, discoloration occurs, etc. It's bad for your eyes, bad for your skin in excess, and creates ozone in the air which is an environmental pollutant. Normal indoor plants have no need for UV at all. Nor do most food plants -- greenhouse glass blocks UV, for instance.

collegeburner 5y ago

Because UV fades fabric, degrades plastic, damages and discolors wood, etc.

sega_sai 5y ago

I don't think germicide is necessarily good. There are theories that the abundance of allergies and autoimmune diseases is partially caused by excessive cleanliness/lack of exposure to microbes etc.

scotty79 5y ago
I think allergies and autoimmune diseases are partially caused by the fact that people are no longer work infested with parasites in yhe way they were all the time since forever. Parasites suppress immune responses. I think we should figure out how to substitute their influence on humans before we conclude that exposing ourselves to bacteria and viruses a lot is a good thing.
- richardfey 5y ago
  Surely there must be some research on this?

briHass 5y ago

CFL bulbs, especially earlier versions often emitted a surprising amount of UV light. The speculation is that the tight coils of glass would result in breaks in the phosphor coating, letting the UV through. I know I have fixtures that used to have CFLs in them, and any plastic is yellowed significantly.

bradknowles 5y ago
UV in fluorescent bulbs escapes directly through the phosphor itself. No phosphor is 100 opaque to UV, nor does any phosphor convert 100% of UV to visible light. Some phosphor coatings might be better than others, but they will all leak a certain amount of UV.

peterburkimsher 5y ago

"kills germs, especially covid" There's some misinformation that claims to "kill COVID" (which is a symptom not a virus) so therefore the recommendation is to say "deactivates SARS-COV-2". Personally I've been trying to reach out to people with scanning electron microscopes, because there's a hypothesis that I'd like to test. VisualCapitalist have an infographic showing the size of particles, including coronaviruses as 0.1-0.5 microns. I'd assumed a Gaussian bell curve centred around 0.3 micron, but was kindly corrected here on HN that SARS-COV-2 is closer to 0.1 micron. My hypothesis is that UV-C light at 300 nm = 0.3 micron, or 100 nm = 0.1 micron, will cause the particles to resonate. In a less formal way, play them the right beat and make the virus dance itself to pieces. To that end, I bought some UV-C lamps (safely inside plastic boxes) from an aquarium shop. Air filters are all sold out in New Zealand, and suppliers are on holiday. The seller understood, but warned that it can cause sunburn within seconds, and eye damage - so don't look into the blue light! This makes sense because of the size of rod cells in the eye. Then I got a regular PC fan, and ran it overnight, blowing air through the light. It felt like the air became very dry, and increasingly unpleasant. Although it didn't smell "fresh", and the window was open for some ventilation, I'm a little worried about ozone production. Not sure how to test that though. Fabric filters in HVAC will work according to their feature size (like an N95 vs surgical mask), but the difficulty is remembering to change them. So personally I still think UV-C is the solution, I just don't know how to use it safely yet. Certainly it makes sense for disinfecting the mask recycling bins (biohazard infectious substances taken out of the environment = litter picked up) but for ambient air, I'm still learning how to do that safely.

bradknowles 5y ago
Use both UV and good quality HEPA filters, if you can. Heck, you can even get filters that greatly exceed the filtration capacity of HEPA filters, and get objects down to .01 microns, which is a tenth to a thirtieth of the size you’re projecting for the smaller particles. But they are expensive. If you’re interested, look at the IQAir brand.
- peterburkimsher 5y ago
  There's some that were being thrown away at work during the office clear-out before the Christmas holiday, so I do have some filters! Today I went back and tidied up the boxes and found them. Need to figure out how to make an air-tight seal in a cardboard box though; I'm no expert at 3D printing real parts (and I'd need to book time on the Ultimaker or laser cutter).

ezconnect 5y ago

Everything age fast under UV lights so it's suggested to limit exposure to it.