For over a century, ultraviolet light has been known as a highly effective means to destroy microorganisms in water, air, and on surfaces. 

Ultraviolet, or UV, light is the portion of the electromagnetic spectrum that lies beyond purple in the visible spectrum.  The UV spectrum is further sub-categorized into UVA, UVB, and UVC.  It is the latter UVC which is found between 200nm and 280nm wavelength and is used in germicidal applications.  When microorganisms are exposed to this wavelength, the UVC energy destroys the genetic material (DNA) within bacteria, viruses and protozoa, eliminating their ability to reproduce and cause infection.  With UV technology it is possible to inactivate harmful  microorganisms, including E.coli, Cryptosporidium and Giardia.  UV Germicidal Irradiation is an emerging practice in air disinfection, especially in sensitive areas such as hospitals and highly trafficked public buildings.  It is a common practice in municipal and industrial water treatment.   UVC is also ideal for foodborne pathogens making it a reliable method for food treatment such as pasteurization of many juices. 

The emergence and growth of UVC treatment into an array of applications is due to its many benefits:

·         It is well established and EPA approved

·         It is environmentally friendly and may eliminate the need for harmful chemicals in disinfection

·         Unlike chemicals it cannot be overdosed and it does not create harmful  by-products or toxins

·         It does not alter water taste or odor nor effect minerals in the water

The most common form of UV disinfection is by means of a mercury lamp which emits a broad spectrum of light with prominent peaks at 184.9 and 253.7nm.  The former is often filtered out as it generates ozone which is potentially hazardous and not required for most applications.  Germicidal activity typically peaks between 260-265nm and a mercury lamp emission provides sufficient breadth to overlap in this range.   Mercury lamps are tube type bulbs, similar to fluorescent lamps.  While they may be a practical solution for some applications, they have physical and operational challenges which create limitations on usage in some areas. 

UV LED’s operating in the germicidal wavelength range open a new set of possibilities in disinfection when incumbent technology is not suitable.