UV Light From Tanning Lamps

First and foremost is the fact that tanning lamps do not emit artificial ultraviolet light, as artificial light rays do not exist. What differentiates the rays produced by an indoor tanning lamp from those produced by the sun is the spectral distribution and intensity of the rays.

In general, most modern tanning lamps produce light in the UVA range (320 nm to 400 nm) at a higher level than is received on the earth’s surface from the sun and UVB radiation (280 nm to 320 nm) at a lower level. The goal is to generate more effective tanning and less incidence of erythema or sunburn. However, the ultraviolet rays themselves are indistinguishable from sunlight, except in intensity and distribution.

The physiological effects of ultraviolet exposure, such as tanning and the many health benefits, are almost exclusively dependent on the UV portion of sunlight. This is why it is important that suntanning devices generate ultraviolet rays. There are various ultraviolet light sources.

Mercury Vapor Lamps

Mercury-vapor lamps, as used in high-pressure tanning units and some table-top facial models, have a line spectrum with a relatively large amount of UVA and little UVB.

Metal Halide Lamps

Metal halide lamps, in which much of the extreme radiation is absorbed by metal additives and subsequently fluoresces at more desirable wavelengths, produce a more continuous light spectrum with adequate UVA emission.

Low-Pressure Fluorescent Lamps

The low-pressure fluorescent lamp is similar to the metal halide lamp in terms of its continuous energy distribution. However, it is different in the sense that it operates on a low-pressure discharge of the mercury vapor. The dominant emission inside this lamp is at 254 nm. However, the phosphorescent material applied to the inside of the lamp tube absorbs these UVC rays and converts them into rays of longer wavelengths.

There are many different types of phosphors available and through a skillful combination of manufacturing methods, light in virtually every spectrum can be created—from UVB up to the visible light sector. The low-pressure discharge also allows the use of hard-glass tubes that contain minerals that act as a filter for the shorter rays. Additional advantages of the fluorescent lamp are in its moderate operating and production costs, low operating temperature, long life and immediate readiness for use.

The fluorescent lamp’s disadvantages include limited radiation output per lamp, resulting in the need for a greater number of lamps to achieve adequate tanning. However, by use of an exterior reflector system behind the lamps, less radiation is lost. Rather, it is captured and reflected back toward the body; consequently, fewer lamps per side are needed. A relatively short distance between the lamp and the body also is required for this type of lamp.

Reflector Lamps

Reflector lamps are a sub-group of the low-pressure technology that do not require a special, external reflector system. Reflector, or RUVA, lamps come with an internal reflective layer on the inside of the tube, forcing all output to radiate through the front side of the lamp.