Does LED lighting contain Ultra Violet Light

One of the big debates currently circulating about LED lighting is whether or not it contains Ultra Violet (UV) light. You'll find many statements on the internet stating that "LEDs have no UV emissions." Then there are those that say that this isn't entirely true. So which one is it? It depends on how you look at it.

First, it's important to understand what people are actually asking. Most really seem to be worried about one of two things: Is there a health concern from using LEDs, and/or are LEDs better than other light sources for protecting UV film and preserving artwork, artifacts, and décor from ageing and discoloration?

To answer these questions we must initially look at how White Light LEDs are made. Without getting into all of the scientific details of the varying Gallium doping mixtures of semiconductor diodes, it's important to understand that LEDs in and of themselves are incapable of emitting white light. White light is composed of all the colors of the spectrum. While science was able to produce LEDs in the three additive primary colors of light (Red, Blue and Green) and varying hues of these colors, a true white continued to evade them.

It wasn't until 1993 when Brilliant Blue LED's were created that White LEDs could make an appearance. Science discovered that when a Brilliant Blue LED is coated with phosphor, combined with a rare earth compound, the blue light is converted by the phosphor to another color wavelength creating what the naked eye perceives as white light.

Contrary to some common beliefs, the spectrum of the light emitted by this phosphor mix is broadband in nature and emits at longer wavelengths giving a full spectrum of visible light.

It is worth noting that while Fluorescent technology also employs phosphors (the coating on the inside of the fluorescent and CFL lamps), the lighting spectrum when the phosphor combines with LED Lighting is much broader.

With White LEDs, the thickness of the phosphor coating and the amount of yellow in the phosphor itself, in part determines the amount of brilliant blue LED light that is absorbed by the phosphor. This results in the different CRI and Kelvin Temperatures of the LED. The more blue absorbed by the phosphor, the lower the Kelvin temperature and the yellower (redder) the light. This also affects the efficacy of the LED. The lower the Kelvin temperature, the more of the actual LED light is absorbed by the phosphor and the more power it takes to get the same light output.

Now back to our original question, do White LEDs used in general lighting applications contain UV light? Brilliant Blue LEDs used in creating White LEDs do generate some UV (in the 400-425nm range); however, the amount of UV emitted by the phosphor, is less than what is generated. In reality, the final amount of emitted UV is so small as to statistically say that White LEDs do not emit any UV light.

So, is there enough UV emitted to pose a health risk? No, the amount of UV emitted by White LEDs is well less than a single percentage point. For this same reason LED Lighting has become the lighting type of choice for museums striving to preserve valued artifacts and maintain their original colors. However, you would not want to use an unfiltered LED in a clean room where some types of film are sensitive enough to UV to be affected by light down to wavelengths of 415nm.

In conclusion, does LED lighting contain Ultra Violet Light? It depends on how you look at it. White LEDs produce some UV light, but they emit less.