Background in UV
UV light can inactivate microbes in air, on surfaces and in water or other liquids. The degree of UV disinfection is governed by degree of UV exposure of the target microbe. Furthermore, the wavelength of that UV radiation and the microbe itself will impact the overall inactivation.
The use of UV-C (254nm wavelength) as a method for disabling micro-organisms, was discovered in the late 19th century. Around that time, Niels Finsen, a Danish physician, created a UV-C emitting lamp, to successfully treat tuberculosis. This discovery earned him the 1903 Nobel Prize for Medicine and Physiology. Since then, many scientific and engineering papers have been published on the sensitivity of various micro-organisms to UV-C and its germicidal effectiveness.
The degree of UV exposure is expressed as a UV dose (J/m-2, more correctly termed “fluence”), which is the amount of UV light delivered to the target microbe. UV dose is the product of UV irradiance and exposure time, meaning that a higher UV dose could be delivered by increasing the intensity of UV light, increasing the exposure time, or both.
