The tan is characterized by a brownish coloration of the skin. This coloration occurs under the effect of ultraviolet (UV) rays emitted by the sun or tanning lamps. It is caused by the formation in the skin of a black pigment called melanin.
Melanin absorbs UV rays. The formation of melanin is therefore a natural reaction for protecting the skin against UV rays. The resulting tan is a sign that the skin has reacted after suffering deep cellular damage. This is why tanned skin should not be associated with health and beauty.
UV rays and their impacts.
The sun is essential for life. However, excessive exposure to the UV rays it emits can be harmful to health.
The UV rays producing the tan are UVB and UVA.
UVB rays do not penetrate deeply into the skin, as they are generally blocked by the epidermis, the first layer of the skin. They cause redness and burning, also known as “sunburn”.
UVB rays cause new melanin to form in the skin. They produce a “delayed” tan, that is, a tan that appears 48 to 72 hours after exposure to the rays.
The sun is the main source of UVB rays. Artificial tanning lamps can also emit, but in smaller quantities.
UVA rays penetrate deep into the skin, damaging the elastin and collagen fibers. These fibers make the skin supple and elastic.
Unlike UVB rays, UVA rays do not cause the formation of new melanin. They rather activate the melanin already present in the skin, making it more tanned.
UVA rays tan the skin without causing burns. For this reason, artificial tanning lamps mainly emit UVA rays.
The tan produced under the effect of UVA rays appears within minutes of exposure, but disappears quickly.