How do sun tanning beds work with our skin?

Tanning beds typically take the form of two designs. The first is the horizontal bed or capsule, the second is the stand up vertical chamber - both rely on the same principle of trying to mimick the effects of The Sun's UV spectra on our skin. However, the vertical chambers tend to be much stronger than the horizontal lay-down units and will produce an all-around tan while at the same time eliminating pressure points that would occur on your underside.

Whatever the design though, tanning beds contain bulbs which take the form of long fluorescent tubes which contain inert gases, a phosphorous coating and traces of mercury. Electricity that the beds run on ignites the tubes causing the mercury atoms to lose their stability. The only way they can return to their stable state is for them to release energy in the form of UV radiation. Tailoring the phosphorous coating allows the desired UV wavelengths to be emitted while unwanted ones are absorbed.

The best way to understand the natural tanning process is to first get a visual idea of where all the reactions are occurring in the skin. To facilitate this a diagram (Cross Section of Human Skin) has been supplied below; showing the mayor components involved.

Cross Section Of Human Skin

From this we can see that the skin is composed of two main layers. The outer layer of the skin (epidermis) is where the tanning process occurs. UVB light stimulates special cells in the epidermis, called melanocytes (which account for 5% of the cells in the epidermis); to produce a pigment called melanin. This pigment moves through the epidermis while at the same time being absorbed by surrounding skin cells. UVA light then oxidizes the melanin which darkens the skin. Not instantaneous, melanin production takes time and a number of short sessions of UV exposure are needed.

Everyone has the same number of melanocytes (about 5 million) but genetics and heredity are what determine exactly how much pigment will be produced. Two pigments are actually produced: the brown eumelanin and the yellow/red phaeomelanin. People with red or ginger hair naturally tend to produce more phaeomelanin, which is why they find it difficult to tan. Interestingly people who suffer from albinoism are not able to produce melanin because they do not have the enzyme tyrosine present.

Nothing last forever and this holds true for our skin. Our skin sheds itself daily and every month a new epidermis has completely generated. Although as we lose skin cells so we lose what tan we have. A tan has to be maintained, and if lost, completely built up again from scratch.

The beauty about tanning beds is that once a base tan has been safely built up they provide protection from further UV exposure. The melanin collects to form a shield against the penetration of UV rays. But the "base tan" has the equivalent of a SPF of only 3 or 4, which is unfortunately not enough and a sun tan lotion should be used as well. Too many people believe that when they go on holiday that a base tan will adequately protect them, this type of ignorance can result in severe sun burn and the possible development of skin cancer. So please always remember to use sunscreen when you are in the sun.

© The Pink Fridge Online Magazine 2008 - Tanning Beds

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