When scientific studies are aggregated, it appears that each UV wavelength contributes to the overall effectiveness of any sanitizing process. For example, UV-B wavelengths and higher are the only radiation that penetrate the Earth’s atmosphere to reach sea level. Yet, most UV sanitizers have, until recently, concentrated on UV-C at 254nm as the primary wavelength. Right behind this frequency is far UV-C from 207nm to 222nm, which some studies demonstrate better potency against some pathogens. The drawback is that the very nature that allegedly makes far UV-C safe when people are present, i.e. it does not travel as well as UV-B through the atmosphere, renders it ineffective in reaching modest distances from the source. Higher power levels can compensate for this deficiency; however, it is very difficult to produce high-power far UV-C radiation within the narrow bandwidth from 207nm to 222nm. Thus, most lamps claiming to produce this range have other radiation “leakage.” This adds an element of exposure risk. We know this because UV in that range is totally invisible, yet lamps that claim only this range still appear blue to the naked eye.
The two most common UV bulbs are fluorescent tubes and mercury vapor. Due to mercury’s toxic nature and environmental hazard, vapor bulbs were banned in the U.S. in 2008, leaving fluorescent. Although fluorescent and even magnetic induction bulbs contain mercury, levels are significantly lower than with mercury vapor lamps. Sterile-Bright™ bulbs use magnetic induction technology originally invented by Nikola Tesla in 1891.