How Do UV-C Lamps Work?

Ultraviolet Light

• Ultraviolet light is so named because it occupies the portion of the electromagnetic spectrum just above that of visible light--that is, its wavelength is shorter than that of violet light, which has the shortest wavelength in the visible spectrum. Like the visible spectrum, the ultraviolet spectrum spans a wide range of wavelengths--from 400 to 20 nanometers. UV-C light sits roughly in the middle of this spectrum, between 280 and 100 nanometers, and is one type of ultraviolet light emitted by the sun.

Disinfectant

• Sunlight may not actually be the best disinfectant, but it's certainly one of the better ones. UV-C rays are fatal to many disease- and allergy-causing microbes, including the microscopic sources of pneumonia, influenza, cholera, and tuberculosis. Experiments have revealed that the 253.7-nanometer wavelength directly destroys the DNA of such organisms, making cell division impossible and causing quick cell death.

UV-C Lamps

• Lamps that generate UV-C radiation, many of which are compatible with standard fluorescent-bulb fixtures, bombard their targets with sufficiently intense UV rays to effectively sterilize them. They were first used to remove bacteria and viruses from medical equipment, but now consumer-grade UV-C lamps are sold for use in killing the myriad organisms that thrive within homes, especially the dust mites that can live so readily within mattresses or cushions and can cause severe allergies or even asthmatic reactions. In many countries, UV-C lamps are also used for the sterilization of water.

Dangers

• The effectiveness of UV-C radiation as a disinfectant is a property both of the intensity of the radiation and the application time. The energy a lamp puts out is measured in micro-watt seconds per square centimeter, or mW S/cm2, and different targets require different energy levels. Various kinds of mold, for example, require from between 6,000 and 60,000 mW S/cm2 to be killed.

Dangers

• Because UV-C lamps are designed to target and degrade living cells, you should be careful not to expose yourself to any significant amount of the radiation they produce. Furthermore, cheaper lamps can often be a little sloppy with their spectrum, putting off UV-B and even A radiation, which can be environmentally as well as personally harmful. Be careful when disinfecting rooms or items with UV-C radiation and be sure to invest in a quality product.