The ultraviolet radiation in sunlight has both positive and negative health effects, as it is required for the synthesis of vitamin D3 and is a mutagen. Vitamin D has been suggested as having a wide range of positive health effects, which include strengthening bones and possibly inhibiting the growth of some cancers. UV exposure also has positive effects for endorphin levels, and possibly for protection against multiple sclerosis.
Long-term sunlight exposure is known to be associated with the development of some types of skin cancer, skin aging, immune suppression, and eye diseases such as cataracts and macular degeneration. Conversely, sun avoidance is associated with increased mortality.
Ultraviolet
Ultraviolet index