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 about 180 nm. UV photographers subdivide the near UV into: (These terms should not be confused with the parts of the radio spectrum with similar names.) There are two ways to use UV radiation to take photographs - reflected ultraviolet and ultraviolet induced fluorescence photography. Reflected ultraviolet photography finds practical use in medicine, dermatology, botany, criminology and theatrical applications. Sunlight is the most available free UV radiation source for use in reflected UV photography, but the quality and quantity of the radiation depends on atmospheric conditions. A bright and dry day is much richer in UV radiation and is preferable