UV damage of the hair.

Hair is a very important for our self-confidence as well as a very important part of appearance and self-concept. It reflects our personality and hair loss or hair damages are considered aesthetic imperfections and social handicap. Outward part of the hair is a "hair shaft" keratin fiber structure sensible to external effects whether they are mechanical, physical or chemical. Excessive sun exposition is the most frequent cause of hair shaft's structural impairment. Photochemical impairment of the hair includes degradation and loss of hair proteins as well as degradation of hair pigment. Hair protein degradation is induced by wavelengths of 254-400 nm. UVB radiation is responsible for hair protein loss and UVA radiation is responsible for color changes. Absorption of radiation in photosensitive amino acids of the hair and their photochemical degradation is producing free radicals. They have adverse impact on hair proteins, especially keratin. Melanin can partially immobilize free radicals and block their entrance in keratin matrix. It also absorbs and filters adverse UV radiations. Therefore melanin is important for direct and indirect protection of hair proteins. Protecting the cuticle is very important for keeping hair shaft's integrity. One can achieve that by avoiding noxious impacts or by implementation of hair care products with UV filters. Nowadays major studies and researches are conducted in order to create hair care products that prevent hair damage.