UVV light refers to another wavelength in the ultraviolet spectrum. Some UV-C devices also produce light in this wavelength. The manufacturers of these devices promote UVV as an added tool for IAQ control, saying that UVV attacks microorganisms, chemicals, and odors. While this may be true, it is important to understand that UVV (unlike UV-C) will also "attack" occupants in treated spaces by adversely effecting human lungs!
The reason for this is that the shorter (185 nanometers) wavelength of UVV light actually generates ozone. This occurs because UVV light reacts with oxygen to break it into atomic oxygen, a highly unstable atom that combines with oxygen to form O3 (ozone). The American Lung Association states that "exposure to ozone causes a variety of adverse health effects, even at levels below the current standard." And the U.S. Food & Drug Administration says: "In order for ozone to be effective as a germicide, it must be present in a concentration far greater than that which can be safely tolerated by man and animals." The longer (254 nanometers) wavelength of UV-C light, by contrast, provides highly effective air, surface, and water disinfection without producing any harmful ozone.
The materials and methods of UV-C lamp construction determine whether a given UV-C device will produce both UV-C and UVV light or only the safer UV-C wavelength. Bio-Shield UV-C devices do not produce any UVV.