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How Sunscreen Works

Understanding the Sun's Ultraviolet Rays

Ultraviolet light is part of the sun's light spectrum that reaches the earth but is not visible to the naked eye.  The wavelengths of UV light are shorter than visible light, which is why we can't see it and are classified as UVA, UVB, and UVC.

The longest of the three, UVA Rays account for up to 95% of the UV rays reaching the earth's surface. UVA rays penetrate the skin more deeply than UVB rays and are the dominant tanning ray.  Only a few years ago scientists believed that because UVA rays penetrated deeply they had no effect on the outermost layer of skin and had no relation to skin cancer.  Research has since revealed that UVA rays damage skin cells in the basal layer of the skin where most skin cancers occur.

UVB rays are responsible for the sun's visible effects on the outermost layer of the skin.  It plays a key role in the development of skin cancer and contributes to wrinkling.

The shortest wavelength of the three, most of the UVC rays are absorbed by the ozone layer and never reach the earth's surface.

As tanning is the body's reaction to cell damage, no tan is a healthy tan.  Tanning also damages DNA and causes permanent changes in skin connective tissue, which is a direct cause of wrinkle formation.

How Sunscreens Work

There are many different sunscreen products on the market that protect against a variety of factors depending on the formulation.  The basic principle of all sunscreens is to protect the skin against the harmful effects of the sun by absorbing, reflecting, or scattering the sun's rays.

UV filters contained in sunscreen are either organic or inorganic.  Most UV filters are organic and form a protective film on the skin that absorbs the UV radiation before it penetrates the skin.  Inorganic filters reflect UV away from the skin.  Most commercial sunscreens contain a combination of both.

Active Ingredients in Sunscreen and What They Do

In order to receive the greatest protection from you sunscreen product be sure to look for the word broad-spectrum on the label.  Broad-spectrum sunscreens help to protect against both UVA and UVB rays. Broad-spectrum ingredients include:

• avobenzone (Parsol 1789)
• cinoxate
• ecamsule (Mexoryl SX)
• menthyl anthranilate
• octyl methoxycinnamate
• octyl salicylate
• oxybenzone
• sulisobenzone
• titanium dioxide
• zinc oxide

Effectiveness of the ingredients and the protection they provide depend on the amount used in the preparation and the combination of active ingredients.