Suntan is a form of skin protection from UV rays.
It consists in coloration of melanin, a pigment which is responsible of the color and it is situated in the skin, in the hair, and in the eyes. People who do not have melanin are the so-called sick of “albinism”.
When we go out in the sun, in the UV rays, either they come from the sun or from a bronzing machine, our skin reacts in a different way according to the type of rays it receives. UV rays are divided into three categories:
UVA: These rays, which do not have a lot of energy, penetrate thoroughly in the skin, reaching the dermis. They are present in percentages over 95% in solar light and they provide a direct suntan. The UVA color the melanin giving us a pleasing bronzed color.
UVB: These rays, which have medium energy, have less ability to penetrate in the skin. The UVB stop between the dermis and the epidermis and they could be responsible of irritations or sun rashes.
They have the merit of stimulating melanocytes to the production of new melanin.
UVC: They are high energy rays which do not penetrate the skin (they just stop at the first stadium), but they are highly harmful for man. They are nor present neither in solar light (they are filtered by the ozone, hole permitting), or in bronzing machines (they are filtered by cobalt filters in high pressure machines or by phosphor in the low ones).