UV Light Facts

To the Left of the Rainbow

The light we see is just a small portion of the electromagnetic spectrum. This energy is measured by wavelength which ranges from long waves (radio waves - the size of buildings) all the way to very short waves (gamma radiation - the size of atoms). Waves of visible light are 400 to 700 nanometers (nm) or about the size of the smallest microbes while ultraviolet light has a wavelength of 180 - 400nm or about the size of individual molecules.

Know your UV A-B-Cs

Ultraviolet light is classified into three categories according to wavelength:

UV-A (320-400nm) is the type of light emitted by a “black light”, a type of lighting used in nightclubs and attractions that makes certain materials seem to glow. It is also used to attract insects to bug zappers (however the bugs are not killed by the UV light, they are electrocuted). UV-A is the safest sort of UV light, limited exposure poses no significant risk to the skin or eyes.

UV-B (280-320nm) like UV-A is present in sunlight and passes through the atmosphere. Unlike UV-A, exposure to UV-B does pose health risks ranging from sunburn to skin cancer. There are, however, medical uses for UV-B light including the treatment of vitamin D deficiency and skin conditions such as psoriasis and vitiligo.

UV-C (180-280nm) is the wavelength of UV light used for germicidal applications. These include water purification, food service sanitization, laboratory sterilization, and of course air purification. UV-C is blocked by the atmosphere so there is no risk of exposure to humans from sunlight. In normal operation a germicidal UV-C lamp is inside the air handling system and is completely safe for people and pets in the home.