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Dan Llewellyn of MaxMax.com writes:
While shopping on Amazon recently, I noticed a number of people selling 'UVC LED Lamps' for disinfecting surfaces. One that caught my eye is advertised as a 100 Watt UVC bulb suitable for sterilizing the home, office, warehouse and supermarket. We have LED flashlights that range from 255nm to 1600nm with over 40 different wavelengths. There is not other shop in the world that carries the frequency range of LED flashlights - over 55 for our XNiteFlashF series. I also know that LED's below 350nm get very expensive and the lower the frequency, the more expensive. We have a 3 Watt 255nm LED light that costs over $600.
BTW, this is also why most of the UV LED's flashlights sold at places like Amazon are misrated. A small 400nm LED might cost $0.05/PC while a 365nm LED might cost $0.50/PC. Almost every UV LED manufactured in China is misrated by 10-20nm. So I figured if the 100 Watt 254nm LED being sold on Amazon, it would be an incredible bargain at $59.95, but I had my suspicions.
We have over 10 different spectrometers covering light from 180nm to 1600nm, and we have a variety of light integration spheres, fiber cables, calibrated light sources, tunable light sources, collimating lenses, cosine correctors, etc, etc.
UV light above 200nm is classified as:
UV-A is the range where you have a blacklight tubes that you see in bars, discos, rave parties, etc. UVA is pretty innocuous. Over long periods of time with enough intensity, you can increase the likelihood of cataracts, but for the most part, you don't need to worry about it.
UV-B is the range where many tanning beds operate. You can get sunburned with UVB. Your body also uses UV-B light to create Vitamin D, so a bit of UVB is actually good for you.
UV-C is the range where the light is germicidal. The light will sterilize things but that is also dependent on the type of thing you are trying to kill, light intensity per unit area, wavelength and time of exposure. UV-C light can give you a cornea burn very quickly but you won't know for a few hours. We have a cheap plastic flashlight with a 4 Watt 254nm bulb that has about 1 Watt of output power. I once looked into it for about 3 seconds and 3 hours later, my eye felt llke I rubbed them with sandpaper. UVC light is no joke, and you need to take precautions when around it.
I measured the Amazon UV LED light, and found that, surprise, surprise, the light is a 395nm LED light. 395nm is not going to be killing anything so save your money on buying a similar bulb.
Below is the spectrometer measured output. Also includes is a trace of an actual 254nm Mercury low pressure germicidal bulb so that you can see the difference. The blue trace is the LED bulb and the red trace is a real germicidal bulb.
Same data below, not as attractive, but gross pattern maybe easier to see.
WIND: China gifted us COVID-19, and now is now defrauding us with products that further put people at risk.