Therapeutic Skin Care's Blog

Visible Damage UVA and UVB

July 9th, 2018 • Posted by Lupe Guthrie • Permalink

According to The Skin Cancer Foundation, ultraviolet light contains UVA and UVB rays. UVA rays account for up to 95 percent of the ultraviolet radiation reaching the Earth’s surface. These long wavelength rays are present with relatively equal intensity during all daylight hours throughout the year. It is important to know that UVA rays can penetrate clouds and glass, which means, unless someone is in a dark room with no windows, UVA rays can reach exposed skin and cause photoaging. UVA rays penetrate the skin below the dermis and go into the lower layers of the skin, the epidermis. Studies show that UVA damages keratinocytes in the basal layer of the epidermis, where most skin cancers occur.

UVB rays are short-wavelength rays that cause the top skin layer or dermis to darken. UVB rays are responsible for tanning, or sunburns, when the skin is exposed for too long. UVB plays an important role in the development of skin cancer. Although UVB rays are most typically active between 10 a.m. and 4 p.m. from April to October, UVB rays can burn and damage the skin year-round, especially at high altitudes or on reflective surfaces such as snow or ice, which bounce back the rays so that they hit the skin twice. Fortunately, UVB rays do not significantly penetrate glass.

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