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by geoduck14
147 days ago
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Old-school UVC lights do produce ozone, and it needs to be taken care of. Newer lights (might) use LEDs that do not produce ozone. I only use LED uvc lights. Also, and this is key: DO NOT look at the uvc light. It can damage your eyes. It is safe for your skin, but it is not safe to look at. |
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Ozone is produced at wavelengths below 242nm, but at very low levels. Significant ozone production only ramps up at wavelengths below 200nm (note the log scale in the figure https://onlinelibrary.wiley.com/doi/pdf/10.1111/php.13391) Whether or not the light is produced by an LED is immaterial--what matters is the output spectra.
There are no UVC LEDs that I would consider "safe" for either eyes or skin, except insofar as they are safe because they output very little light, or no UVC at all. SilannaUV makes a 235nm LED, but much of its spectrum is outside the relatively safe "far-UV" band.
Krypton-chloride lamps produce near-monochromatic 222nm, and generally are sold filtered to remove even traces of non-far-UV wavelengths. These are relatively safe because at 222nm, protein absorption in the outer layers of human tissues is so high that the photobiological risk is likely low, especially in skin. I still don't recommend staring directly at those lamps for extended periods of time, especially close up, but this is the only kind of lamp that I might consider 'safe'.
Essentially, if it doesn't produce ozone, it is likely a significant photobiological hazard--unless it's just producing very low levels of light, or not producing UVC at all. Many "UVC" lights you can buy online aren't really UVC at all.