It has long been known that solar ultraviolet (UV) radiation is a carcinogen, especially UVB. Sunlight is composed of several light waves including ‘invisible’ light with 3 types of UV at different wavelengths. Solar radiation breaks down into three families: ultraviolet (UV), infrared (IR) and visible light. If the infrared are not insignificant (heat, insolation, which penetrate to the hypodermis …), they do not burn the skin. It is better to focus on ultraviolet A, B and C. UVA penetrate deep into the skin, can cause skin changes, photo aging, collagen degradation, elastin … UVC are the most dangerous but are normally completely stopped by the ozone layer.
UVB penetrates only the superficial layers of the skin. However, their activities are very strong. They are responsible for tanning but also sunburn (erythema), they burn. In addition to activating melanin, they produce high doses of free radicals, accelerate skin aging and disrupt the production of collagen and elastin. They are also the leading cause of skin cancer in the broad sense.