Minimum Erythemal Dose: the minimal dose of UVs that a person may receive before getting sunburnt (250 J/m² for normal skin).

Natural pigment synthetized by the melanocytes, it is responsible for the pigmentation of the skin and the hair and ensures protection against the harmful effects of the sun. It is an internal filter which absorbs and reflects the UVs.

Cells of the epidermis or of the hair follicles responsible for the synthesis of melanin.

The main elements which constitute the cell membranes. They play an essential role in the semi-permeable function of the plasmic membrane.