The Sun
Reducing your exposure to the sun is the best way to keep your skin healthy. Here's why:
Sunlight consists of two types of ultraviolet (UV) rays that damage skin - UVA and UVB rays. UVC rays, another spectrum in sunlight, are also potentially harmful, but the ozone layer blocks them from reaching the earth. UVA and UVB rays are present all year and are hazardous whether they are direct or reflected.
When the sun's ultraviolet radiation reaches the surface of the skin, the skin reacts by producing melanin - otherwise known as a tan - to protect itself. UVA rays are milder than UVB rays, but because their wavelengths are longer, they penetrate deeper through the skin's layers. UVA rays contribute to wrinkling and burning the skin, as well as to the development of skin cancer. UVA rays also are used in tanning booths. Advertised as a method to tan safely, artificial UVA rays in tanning booths not only inflict the same type of skin and eye damage as the sun, but also may be as much as 20 times stronger than natural sunlight. UVA rays can also pass through window glass.
UVB rays are the main cause of sunburn and skin cancer. This type of sunlight intensifies during the summer and can do more damage more quickly than UVA rays. The epidermis absorbs most of the intensity of UVB rays. UVB rays cannot pass through glass. Sunscreens should be an important part of your skin health routine because they absorb UV rays.
Sunscreens are rated by how much sun protection factor (SPF) they offer. SPF calculations are based on laboratory comparisons of how much sunlight will cause a mild sunburn on the unprotected skin of a person with a fair complexion and on the same skin area protected by sunscreen. A product rated SPF-15 is designed to provide approximately 15 times more protection for a person whose skin burns in about 10 minutes of sun exposure. Wearing sunscreen with SPF15, she would be able to be in the sun 150 minutes longer than without protection. Most SPFs of 15 or higher will protect against both UVA and UVB rays. Known as broad-spectrum sunscreens, these products contain titanium dioxide. Other active ingredients are zinc oxide, oxybenzone, or Parsol 1789. While sunscreen helps to minimize damaging sun burns, it doesn't completely prevent burning.
Use a sunscreen with SPF 15 or greater all year for all skin types. Sunscreens with SPFs above 15 only provide 2 percent to 3 percent more protection than those with lower SPFs and are likely to contain high concentrations of the active ingredients, which may cause rashes in people with sensitive skin. If you're prone to rashes, it's better to reapply a sunscreen more often than use one with a higher SPF. However, higher SPF sunscreens may not rub off as easily.
Lotions, oils, gels, and creams can all be effective sunscreens. Oils usually contain fewer sunscreen ingredients and generally have an SPF of less than two. All sunscreens need to be reapplied after water contact or sweating. Gels wash off more easily and need to be reapplied more frequently, but may be preferable if you are acne-prone. In any case, it is important to reapply sunscreen every one to two hours if exposed to direct sunlight.