UV-A is the source of suntanned skin. With its relatively longer wavelength, it can penetrate the atmosphere. Applications included tanning beds and treatment of skin diseases plus insect lights.
UV-B is in the middle wavelength of the ultraviolet spectrum and has been used to treat skin diseases.
UV-C, or short wave ultraviolet radiation, is used to destroy bacteria, mold, viruses and other biological contaminants in the air, in liquids, or on surfaces.
UV-V is produced by ultraviolet lamps which produce ozone. This occurs because UV-V light reacts with oxygen to break it into atomic oxygen, a highly unstable atom that combines with regular oxygen atoms to form O3 (ozone). Ozone is good for the upper atmosphere but terrible for your lungs.
Ultraviolet rays with the UV-C wavelength will destroy pathogens such as viruses, bacteria, mold, and mildew. This component of sunlight is the main reason that microorganisms die in outdoor air. The UV-C rays break through the outer membrane of microbes like yeast, mold, bacteria, viruses, or algae. When the radiation reaches the DNA of the microbe, it causes modifications. The DNA then transmits incorrect codes and this causes the death of the microbe.
Ultraviolet germicidal lamps provide a much more powerful and concentrated effect of ultraviolet energy than can be found naturally. Such lamps sanitize air that is passed directly in their path to destroy pathogens that come in contact with the UV rays. Musty, moldy type odors can be eradicated, along with tuberculosis, cold and flu viruses, smallpox, and other airborne diseases. This system is particularly beneficial to those suffering from allergies. Common allergens are molds, mildews, and fungi. These microbes would be destroyed, improving the health of the allergy sufferer.
Ultraviolet germicidal irradiation has been studied since the 1930’s and has been used to destroy the same microbes that cause indoor air pollution. For many years, the medical industry has used UV light to sanitize rooms and equipment. The Centers for Disease Control recommend UV lamps for their germicidal effect. FEMA recommends it's use for counter-bioterrorism