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Next in frequency comes ultraviolet (UV). In frequency (and thus energy), UV rays sit between the violet end of the visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC.
Because UVC can be deadly, a special dichroic filter glass (usually purple) is required that will filter out the UVC and UVB. The goal with high-pressure tanning bulbs is to produce a high amount of UVA only. Unfiltered light from a high-pressure lamp is rich in UVC used in germicidal lamps, for water purification, but it damages human skin.
UVA 315–400 Ultraviolet B 3.94–4.43 0.631–0.710 Medium-wave UV, mostly absorbed by the ozone layer: intermediate UV; Dorno radiation. UVB 280–315 Ultraviolet C 4.43–12.4 0.710–1.987 Short-wave UV, germicidal UV, ionizing radiation at shorter wavelengths, completely absorbed by the ozone layer and atmosphere: hard UV. UVC 100–280
 Narrowband UVB lamps, on the other hand, emit light in the 311-312 nanometer range. These lamps require a dose of 2 joules per square centimeter to achieve the same therapeutic effect as a 293 nanometer lamp, which is 20 times higher.
This file is a work of a U.S. Army soldier or employee, taken or made as part of that person's official duties. As a work of the U.S. federal government , it is in the public domain in the United States.
There are four UVB types of lamps: Fluorescnt Broad-Band UVB that emit 280-330 nanometer, Fluorescent Narrow-Band that emit 312 nanometer, Excimer that emit 308 nanometer and LED that emit 290-300 nanometer. PUVA means UVA + psoralen. It consists of irradiation of the skin with the UVA ultraviolet light, from a fluorescent bulb or LED lamps.
The location of 'far-UVC' radiation (200-235 nm) in the electromagnetic spectrum. Far-UVC is a type of ultraviolet germicidal irradiation being studied and commercially developed for its combination of pathogen inactivation properties and reduced negative effects on human health when used within exposure guidelines. [1] [2] [3] [4]
UV classifications include UVA (320-400 nm), UVB (290-320 nm) and UVC (200-280 nm). UV-absorbing compounds are used not only in sunscreen, but also in other personal care products, such as lipstick, shampoo, hair spray, body wash, toilet soap, and insect repellent. [ 2 ]