[raxxorrax]

One should be aware that these wavelengths might not be particularly healthy for your skin and can result in sunburns without causing the usual red skin symptoms. You should also not look into the light source and wear special glasses if you handle UV light.

[LinuxBender]

Agreed. Safer would be 222nm UVC as it can't penetrate the outer layer of the eye. This is what medical facilities actually use. Unfortunately no LED's exist that can emit in this range at a useful output power. This is still limited to excimer lamps. There are LEDs in this range, but they can't emit high enough output to break down genetic material.

[raxxorrax]

There are some devices with mercury vapor lamps for applications that require a broader spectrum. True though that LED have mostly just one peak and then open up in visible wavelengths again.

Theoretically it should be safe, but I would still use glasses, since even outer layers of your eye are probably photosensitive, not only your retina.

But yes, UVA specifically is dangerous for skin too, since it travels deeper without causing sunburn symptoms but still damaging the tissue, so a shorter wavelength might even be preferable.

[dave_4_bagels]

The problem with mercury vapor lamps with a broader spectrum is that they produce ozone gas. I've observed this first hand with a philips UV bulb I purchased. Even though this lamp supposedly has a "doping" agent to help block unwanted wavelengths that produce ozone.

[dave_4_bagels]

Yeah, far UVC is great for the exact reason that it's far less harmful to human skin. However, "far uvc" (207-222nm) leds are even more expensive. Many far uvc devices aren't available to general consumers (to control demand). The units that are available to the general population are incredibly expensive, at least $2k for a lamp large enough for use in a small bedroom.

https://www.ushio.com/product/care222-filtered-far-uv-c-exci...