Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Jimbee on 04/09/2025 16:03:28
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I got a couple of UV wands I have been using to sanitize things around my home. I know one of my doctors recommends it for my shoes, which are hard to wash otherwise.
This had me thinking of using sunlight to sanitize things. I just know the UV radiation in sunlight does sanitize, I just don't know how much. Would it have any effect on your hands this way? What if it was a sunny day, you were outside, and you let the sun shine on your hands for a couple of seconds? Would it do anything? Would there be any point in doing that even?
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Some pathogenic organisms are susceptible to uv radiation but others are quite resilient. I would not rely on this idea if I thought dangerous bacteria/viruses/fungi were in my environment. Intense uv, like one gets with a naked mercury vapour discharge lamp can be quite effective at sterilisation but this is inherently hazardous- the sun in comparison produces much weaker levels and only for a couple of hours either side of noon. Exposing one's hands to full sunlight for a couple of seconds would have zero effect, IMHO.
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UV kills microbes by breaking the bonds in their DNA (and other organic chemicals).
- breaking the bonds in DNA causes mutations, and different organisms have different abilities to achieve DNA repair.
- Shining strong UV light on your hands would also damage DNA in the living cells at the base of your skin; the resulting mutations might produce a cancer like melanoma (in perhaps in 10 or 20 years time).
During COVID, it was suggested that we could put UV LEDs in air-conditioning ducts (ie where humans are not directly exposed) in order to reduce COVID spread through air conditioning.
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About ten years ago I was looking for uv leds as a cooler replacement for a mercury vapour lamp for some radical based chemistry but I could not find any that would come close as the wavelengths were all on the very low energy level- I can't remember what was on offer but certainly nothing in the ~250nm range. This situation may have changed by now.
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UVC is bactericidal but also pretty lethal to human skin.
You could put your shoes in a UVC cabinet for an hour or so (remember to turn them over a few times) but sheep dip and agricultural boot wash should be entirely adequate and, used with a scrubbing brush, will actually remove the layer of infected sh1t, axle grease or cooking fat that UVC cannot penetrate.
We wear synthetic rubber boots or closed chef-type plastic clogs in operating theaters, sterilised by superhot steam or ethylene oxide. A pressure cooker will do the job nicely - 20 minutes on "meat" setting. Not recommended for leather shoes but it can make a seagull or kookaburra almost edible.