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I am curious as to whether LEDs like these ones https://www.led4everything.com/index.php/product/waterproof-smd-purple-violet-led-strip-light/ are harmful, they are advertised as UV.

But are they just purple LEDs or actual UV? I see things like this https://www.youtube.com/watch?v=1m0TQjBRcFo and know they are "harmful" but I'm curious if those ones are too. I know that even regular white LEDs can be considered "harmful".

Can UV Leds be harmful to humans?

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  • \$\begingroup\$ This site is not for discussions. Is there a specific question? \$\endgroup\$
    – Eugene Sh.
    Commented Jul 13, 2018 at 18:56
  • \$\begingroup\$ By discussion I mean answers for my question above, sorry for that I don't use this site frequently. Which the question is, are these safe or actual UV? The listing does not mention and I'm just curious about the safety of LED's like this. \$\endgroup\$
    – Luke Callan
    Commented Jul 13, 2018 at 18:57
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    \$\begingroup\$ You should look for a datasheet that specifies wavelengths. I can't find one off-hand when I look at the links you gave. You might have to email them and ask for a datasheet. \$\endgroup\$
    – Cort Ammon
    Commented Jul 13, 2018 at 19:00
  • \$\begingroup\$ It's hard to tell as there is no technical data. You could tell by actually looking at the wavelength chart of the LEDs. When you say safety - which aspect you are talking about? The power level of these things is not high enough to harm your skin, but probably not very healthy for your eyes. \$\endgroup\$
    – Eugene Sh.
    Commented Jul 13, 2018 at 19:00
  • \$\begingroup\$ I see, thank you guys for the insight. I'll do some research, thank you again \$\endgroup\$
    – Luke Callan
    Commented Jul 13, 2018 at 19:01

3 Answers 3

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Can UV LEDs be harmful to humans?

Yes.

You need to look at IEC EN 62471. Photobiological safety of lamps and lamp systems. https://www.bentham.co.uk/knowledge/insights/articles/photobiological-safety-of-lamps-history-and-overview-of-standards-240/

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The strip of LEDs claims to emit "purple color". According to the common color chart,

enter image description here

the visible "purple color" corresponds to wavelength of about 400 nm.

[CLARIFICATION: In this particular case this seems to be an ordinary 365-nm InGaN LED. A phosphor-based LED would have a deep-UV driver, which are very expensive to make and their luminous efficiency is fairly low, and there is no sense to make them for household illumination purposes. As it is known, most light "conversion" occurs by Stokes shift into lower-frequencies, so for a 365-nm LED there could be no shorter wavelength in the emission spectrum than the main excitation line.]

On the other hand, there is an established model for sensitivity of live tissues to UV emissions, called "CIE action spectrum", which looks as this:

enter image description here

The interpretation of this chart is that any UV light longer than 320 nm is pretty harmless to living organisms and plants, while lights shorter than 300 nm have 1000X more effect and, with some intensity, would cause harm.

The "germicidal high-pressure Mercury lamps" have strong emission lines at 180 nm and 250 nm, and that's why they are petty harmful to skin and bacteria.

In short, the referenced purple light has 1/10,000 effect as compared to "true UV-B-C lights" that are used to kill bacteria in industrial water purification systems, so the strip is more like a toy. Of course, if you wire a thousand of these strips, there could be some trouble when human skin is in near proximity.

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    \$\begingroup\$ In general, you can't assume that something that is emitting a visible purple light is not also emitting invisible UV with a lot more energy - the visible portion could be only a weak sidelobe. It may be possible to deduce things from a sound knowledge of LED technology, but this response seems entirely based on the mention of a visible component in the marketing literature, which is not a reliable basis for conclusions. \$\endgroup\$
    – Chris Stratton
    Commented Jul 13, 2018 at 21:52
  • \$\begingroup\$ @ChrisStratton, in general one can't assume anything, this is true. But in this particular case there is an extremely high probability that this is an ordinary 365-nm InGaN LED, and not some deep-UV LED with "pink phosphor" on top, which would have no sense to make, especially for household illumination purposes. As you might know, most light "conversion" occurs by Stokes shift into low-frequencies, so there could be no shorter wavelength in the emission spectrum than the main excitation line (unless you have some anti-Stokes upconverting material). Therefore your remark has little grounds. \$\endgroup\$
    – Ale..chenski
    Commented Jul 13, 2018 at 22:57
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    \$\begingroup\$ While this is true for most damage mechanisms caused by UV light, note that wavelengths up to 500nm and particularly in the range 400-450nm are considered to be able to cause damage to the eye in sufficient intensity. If you're spending a lot of time around bright deep-blue/near-UV light sources, wearing red-tinted glass would be a good idea. And avoid staring at blue LEDs. \$\endgroup\$
    – Jules
    Commented Jul 14, 2018 at 20:52
  • \$\begingroup\$ @Jules, yes, with sufficient intensity anything can happen. I remember a 40-W CO2 laser burning holes in a 3-inch brick... \$\endgroup\$
    – Ale..chenski
    Commented Jul 14, 2018 at 21:01
  • \$\begingroup\$ @Jules: absolutely correct! "Blue light hazard" is one of the often underestimated risks to the eye. Even cheap 20 mA blue LED can damage the retina like nothing. \$\endgroup\$
    – datenheim
    Commented Dec 26, 2022 at 23:04
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Yes, the blue and purple can harm your eyes, UVA and UVB can harm eye and skin, and UVC mainly skin and other tissue.

It depends on intensity or radiance and dosage.

Your link did not work for me.

If you need few more details about UV hazards: ICNIRP UV guidelines and Directive 2006/25/EC LED: Statements about LED safety :-)

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