# Hand dryer UV



## KDM (Jul 27, 2013)

I guess I don't get out enough. Tonight I went with my wife to the mall. During my trip to restroom I had a new experience (no jokes ha). After washing my hands I use the hot air dryer that's equipped with a UV light. The light aims at your hands to kill germs while also drying them. Oh well, I thought it was pretty cool anyway.


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## mattp (Jul 28, 2013)

Pretty cool until you get skin cancer.


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## KDM (Jul 28, 2013)

I'm a lot more worried about what Fukushima is spewing than I am a UV light.


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## AnAppleSnail (Jul 28, 2013)

How do you know it's UV? UV LEDs are pretty dangerous as far as bathroom fixtures go (Risk of permanent eye damage without obvious warning). The 'cool glow' hand driers I've seen have a neat blue glow from royal blue LEDs, but not UV. Test method: Find UV-fluorescent plastic and blue-fluorescent plastic, and see which one lights up better. Second check: Only EXTREMELY power UV LEDs are visible to the naked eye in normal conditions.


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## Ken_McE (Jul 28, 2013)

KDM said:


> I use the hot air dryer that's equipped with a UV light. The light aims at your hands to kill germs while also drying them.



I deal with these people. It may just be a sales gimmick. There would be some tension between the need for powerful deep UV to actually kill anything, and the need to not injure customers. I know which way I would choose if I were a manufacturer.


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## mattp (Jul 29, 2013)

KDM said:


> I'm a lot more worried about what Fukushima is spewing than I am a UV light.



True, in the scheme of things it may not be a big risk, but even a small risk of skin cancers on your hands for the questionable benefit of a few less bugs is not worth it. Cutting things out from hands is a PITA; make a fist then see how much loose skin you've got on the back of your hand to see why. You'd probably have to have pretty severe hand washing OCD to get enough exposure from that machine to cause any problems though, if there's even any UV being emitted (which I doubt).
I have heard of hand dryers with HEPA filters and UV directed at the airflow (rather than your hands), to prevent bacteria etc being blown onto your hands, which is an interesting idea.
Cheers,
Matt


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## markr6 (Jul 29, 2013)

Sounds like overkill to me (if it was UV). I immediately think of the quote from The Office - "How bad are you at going to the bathroom?" LOL!


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## KDM (Jul 29, 2013)

I hope my next shopping trip to the mall is so far into the future that they will have already changed those dryers to the 2020 models. Seriously, they may or may not have been UV but I won't be back for a while to take a second look.


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## JacobJones (Jul 29, 2013)

I had a similar shock once when trying to use toilet, taps, soap dispenser and dryers in a motorway service station, turned out everything was fitted with motion sensors. Good idea but flawed because you have to use a filthy door handle to get out after washing your hands.


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## PhotonWrangler (Jul 29, 2013)

I've run across those dryers myself and I also thought it was UV at first. Upon closer inspection it turns out that it's just a blue LED, probably just a gimmick to increase the "perceived value" of using the dryer instead of paper towels. Or it's a pilot light to tell you that the blower is running - just in case you couldn't tell from the rushing air.


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## markr6 (Jul 30, 2013)

JacobJones said:


> I had a similar shock once when trying to use toilet, taps, soap dispenser and dryers in a motorway service station, turned out everything was fitted with motion sensors. Good idea but flawed because you have to use a filthy door handle to get out after washing your hands.



LOL I know! Usually there's a pile of paper towels or toilet paper on the floor nearby since people use those to open the door. I wish they would always PUSH from the inside so you could just kick the door open when exiting.


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## Oznog (Oct 22, 2013)

"UV" covers a WIDE range of wavelengths. For understanding, 3 subranges are relevant to this situation:

UV-A is 400 – 315 nm. It includes plain ol' visible purple colors. It's "blacklight". It causes fluorescence of blacklight posters. Almost ALL "UV LEDs" are UV-A- most are 395 nm, some 365nm. It has relatively little biochemical or photochemical action, but is weakly implicated in skin cancer- surely not until the shorter wavelengths.
UV-B is 315 – 280 nm. 
UV-C is 280 – 100 nm. THIS is a germicidal lamp (not done with LEDs). It's DANGEROUS to eyes... and skin... and would NEVER be sold in an application where people would be exposed to it. And it'll damage many types of plastics.


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## PhotonWrangler (Oct 22, 2013)

Oznog said:


> UV-C is 280 – 100 nm. THIS is a germicidal lamp (not done with LEDs). It's DANGEROUS to eyes... and skin... and would NEVER be sold in an application where people would be exposed to it. And it'll damage many types of plastics.



A long time ago some hand driers actually had small UV-C lamps built in, and the lamp would shine directly onto your hands. That was before the dangers of UVC were widely understood.


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