Why are ultraviolet lights not more commonplace if they are so effective at sanitizing?

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Wouldn’t it make sense to install UV lights in bathrooms? Over doors and possibly on door handles? I’ve seen wearable UV lights, but I don’t see it being worn by frontline personnel.
We have seen social distancing indicators, plexiglass dividers and masks become commonplace. I feel like UV light should also be more commonplace, but it isn’t. Why not?

In: Technology

UV light damages sensitive tissues – like the retinas – for the same reasons it is so good at sanitizing things. It would not be good thing to have sanitizing UV-C light everywhere, as it would cause harm to the people it was trying to protect.

I’ve never seen a wearable UV sanitizer before for this reason – not all UV light is _sanitizing_ UV light, so it is possible those wearable UVs are not the kind of light that does any good.

UV-C light is hazardous to most living things. Skin exposure to germicidal wavelengths of UV light can produce rapid sunburn and skin cancer. Exposure of the eyes to this UV radiation can produce extremely painful inflammation of the cornea and temporary or permanent vision impairment, up to and including blindness in some cases.

For the same reason it’s bad for germs, it’s bad for people too. When it’s aimed away from people it can be helpful, but wearing it or putting it over things that people touch or go through would sanitize at the expense of increased skin cancer rates

It’s not just any old UV light, there are specific wavelengths of ultraviolet that are detrimental to microbes and viruses. But those wavelengths are also pretty detrimental to humans. So it’s not really a good idea to bathe people in those lights all the time. There are ways of passing air through ducts that have those particular UV lights installed, and that air gets sanitized, at least somewhat, without exposing people directly to the UV. Another problem is that the UV exposure has the last for more than a few seconds, so in those duct systems they generally need a nice long run of ductwork where there is UV lights installed to give the air enough time under exposure. And then of course there’s additional expense associated with the sanitation grade UV lights, that are much more expensive than typical light bulbs and UV lights you can pick up for a few bucks from Amazon. That said, people are working on really clever ways to get the benefit of UV exposure with less risk.

Wow! I got some really great answers in such a short period of time. I had no idea UV light could be harmful, but it makes sense. I didn’t realize that it was only specific wavelengths that were effective, too.
Thanks for the thoughtful and informative answers, everyone!

UV light also damages other things like plastic and people. Sit next to a UV light long enough and you’ll get sunburned. Stare into it and you can go blind.