Sun tanning However, it operates not by inducing direct DNA damage, but by producing reactive oxygen species which damage DNA indirectly. UVA (see above) induces a cosmetic tan but little extra melanin protection against sun damage, sun burn, or cancer. Ultraviolet B (UVB) radiation is in the wavelength range 280 to 320 nm. Much of this band is blocked by the Earth's ozone layer, but some penetrates. UVB: A person's natural skin color affects their reaction to exposure to the sun. An individual's natural skin color can vary from a dark brown to a nearly colorless pigmentation, which may appear white .
Ultraviolet photography and it allows only the radiation to pass which is needed to induce a particular fluorescence. As before, a barrier filter must also be placed in front of the camera lens to exclude undesired wavelengths. Ultraviolet photography was used as evidence in court at least as early as 1934. Photographs made with ultraviolet radiation can reveal bruises or scars not visible on the surface of the skin, in some cases long after visible healing has completed. These can serve as evidence of assault. Ultraviolet imaging can be used to detect alteration of documents. Ultraviolet photography Ultraviolet photography is a photographic