Beauty Glossary (U)

Beauty terms from Undertone to UVA and UVB

Undertone ... In make-up terms, undertone, refers to cool or warm skin tones.

Ultraviolet Light ... Our sun emits ultraviolet radiation in the UVA, UVB, and UVC bands. The Earth's ozone layer blocks 98.7% of this UV radiation from penetrating through the atmosphere. 98.7% of the ultraviolet radiation that reaches the Earths surface is UVA.

UVB and UVC radiation is responsible for some of the generation of the ozone layer.

UVA Ultraviolet light Type A ... These are rays of light from the sun which are not visible but can cause damage to the skin.

• UVA is known to contribute to skin cancer via indirect DNA damage (free radicals and reactive oxygen species). It penetrates deeply but it does not cause sunburn. UVA does not damage DNA directly like UVB and UVC, but it can generate highly reactive chemical intermediates, such as hydroxyl and oxygen radicals, which in turn can damage DNA

UVB Ultraviolet light Type B ... These are rays of light from the sun which are not visible but can cause damage to the skin.

• Exposure to UVB induces the production of vitamin D in the skin. The majority of positive health effects relate to this vitamin which has regulatory roles in calcium metabolism, which is vital for normal functioning of the nervous system, for bone growth and maintenance of bone density, immunity, cell proliferation, insulin secretion and blood pressure
• Over-exposure to UVB radiation can cause sunburn and some forms of skin cancer. In humans, prolonged exposure to solar UV radiation may result in acute and chronic health effects on the skin, eye, and immune system. However the most deadly form - malignant melanoma - is mostly caused by the indirect DNA damage (free radicals and oxidative stress). This can be seen from the absence of a UV-signature mutation in 92% of all melanoma