The ultraviolet radiation is fundamental for the plants. For the animals they are unnecessary and often harmful. The long and habitual exhibition can finish with damaging the nucleus of the exposed cells, with what a major facility is had for the malignant transformation (leather cancers); in case of foreseeing a long exhibition the use of creams is essential with high index of protection and to renew his application often, although these creams do not protect of the most malignant of the cutaneous cancers, the melanoma. The radiations ultraviolet of minor wavelength are the most dangerous; although they usually remain retained in the ambience, the current decrease of the ozonosfera (the ozone hole) allows his arrival in major proportion; in places with scarce atmospheric layer, like the high mountain or ski resorts they go so far as to produce irreversible burns in the retina, therefore a few good glasses are essential, in addition to the creams, with anti-ultraviolet filter.