Our natural skin colour is determined by skin pigment – melanin – and the presence and amount of melanin in an individual is determined by hereditary factors.
When our skin is exposed to UV, cells deep in our skin – called melanocytes – initiate a process where more melanin is produced. This subsequently ‘browns’ as it rises to the skin’s surface producing a tan. UV also causes the outer layer of the skin to thicken. This is the body’s way of building up protection to UV and to help avoid burning.
People will react differently to UV rays – darker skinned people produce melanin more readily. The skin of some very fair people contains very little melanin and, even when exposed to UV, they cannot form melanin, so they will not tan in sunlight or on a sunbed.
If the natural tanning process is rushed, sunburn will result. Our skin has a natural repair mechanism but if this is triggered too frequently, it may become exhausted and result in permanent damage to the skin.