|Ultraviolet (UV) radiation is known to produce erythema and pigmentation on the skin. When directly exposed to the sun, there is 10 to 100 times more exposure of UVA than UVB. UVB (considered the Burning Ray) has an immediate, harmful impact on the skin within minutes. UVA (considered the Aging Ray), which you do not feel, has been shown to damage the skin by penetration deeply into the dermis able of producing premature aging, wrinkles, and tumors.
Sun screens are inactive ingredients that are able, however, to avoid chemically or physically UV radiations (UVA and UVB) to penetrate the skin layers. They provide therefore effective protection from the skin damaging effects of the sun rays. Chemical sunscreens act by absorbing UV-light. Physical sunscreens reflect or scatter light in both the visible and UV-spectrum. Effectiveness of sunscreens depends upon their UV-absorption, concentration, formulation, and ability to withstand swimming or sweating.