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UVB (ultraviolet-B): short-wave solar rays of 290-320 nanometers UVB was long considered as the "tanning ray" and is strongest in the summer months when the earth rotates closest to the sun. When the earth rotates away from the sun in the winter months it is harder to get a "suntan" because the rays can not reach the earth's surface. Sunblocks for many years only blocked the UVB ray as science was not clear on the body's reaction to UVA. Body's Reaction to UVB This ray only has the strength to penetrate the epidermis. The epidermis is the very top layer of the body and the same thickness as a silk scarf. No blood vessels or nerve endings are present and is composed of keratinocytes (skin cells), basal cells and melanocyte cells. Melanocyte cells synthesize tyrosinase and the pigment melanin that is transferred to the keratinocytes or skin cells for color. See the hyperpigmentation or brown spots information section of the store for more facts on darkening of the skin. UVB rays simulate the melanocyte cell to produce more melanin which is more colour known as a suntan or if a very small area known as a brown or age spot. |