Sunscreens are made to protect the skin against the damaging rays of the sun. Ultraviolet B radiation, or UVB, which causes sunburn, damages the outer layer of the skin, and Ultraviolet A, or UVA, penetrates deeper into skin to cause wrinkles, age spots and other signs of premature aging. Both of these forms of skin damage, sunburn and photo-aging can trigger the development of skin cancer. A variety of sunscreen products are available on the market, making it important to learn the differences between types of sunscreen to ensure that you choose the right ones to suit your needs.
Physical Sun Screen
Physical sunscreens protect the skin by reflecting the ultraviolet rays away, preventing them from penetrating the skin. These products use either zinc oxide or titanium dioxide to reflect or scatter the sun's radiation and are effective against both UVA and UVB. Both of these two types of physical sunscreens are very gentle on the skin, rarely causing skin irritation even when used on the sensitive skin of babies. Physical sunscreens should be applied three times a day for effective sun protection, and can wash away with water or heavy sweating, making more frequent reapplication necessary.
Chemical Sun Screen
Chemical sunscreens work differently, absorbing UV rays rather than reflecting them away. These sunscreens generally use a variety of chemical ingredients, each able to absorb UV radiation within a specific wavelength. These products contain one or several of the following active ingredients: avobenzone, which protects again UVA radiation, benzophenone, which absorbs both UVA and UVB, and homosalate, octisalate, oxybenzone and para-aminobenzoic acid, which protect against UVB radiation.
Broad Spectrum Sun Screen
Sunscreens that are labeled broad spectrum have ingredients that protect against both UVA and UVB radiation. These may be physical sunscreens that contain both titanium dioxide and zinc oxide, or chemical sunscreens that use a combination of active ingredients to protect against both forms of UV radiation. These are designed to offer all-around protection against the effects of sun exposure, preventing sunburn as well as deep skin damage.
Waterproof and Water-Resistant Sun Screen
Sunscreens that are labeled waterproof or water-resistant are meant to protect the skin during activities like swimming, sports, or outdoor work, where moisture is present. A waterproof sunscreen is designed to maintain its level of UV radiation protection throughout 80 minutes of water or sweat exposure. Water-resistant sunscreen maintains its UV protection through 40 minutes of exposure to moisture. While these sunscreens have more staying power than the average product in moist or wet environments, they do need to be reapplied regularly according to product directions to remain effective.
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