Sunscreen : What is it?
Sunscreens protect the skin by blocking ultraviolet (UV) rays from the sun. They are usually applied topically and come in different forms, the most common being lotions, sprays, gels, and rub-on sticks. They are commonly used to prevent sunburns in beaches and outdoor environments, and to reduce the risk of skin cancer over time.
Sunscreens are measured by their sun protection factor (SPF), which indicates the length of time they can stay effective per application. This means that a person wearing an SPF 15 sunscreen can safely stay under the sun 15 times longer than one who is unprotected. Common SPF ratings are 15, 30, and 45.
SPF ratings only measure protection against UVB rays, which are responsible for sunburns and topical damage. UVA rays, on the other hand, are more penetrating and are responsible for most skin cancers. Most sunscreens block UVB rays, but not all can protect against UVA.
Kinds of Sunscreens include the following:
Physical sunscreens deflect UV rays and cause them to bounce off and scatter rather than penetrate the skin. They are usually opaque white or cream, and increase in thickness with increasing SPF ratings. Most brands contain zinc oxide and titanium dioxide, which strengthen the skin and make it less prone to burns. They provide both UVA and UVB protection.
Chemical sunscreens absorb radiation from UV rays and release them as lower-energy rays, reducing their harmful effects to the skin. They generally have higher SPF ratings than physical sunscreens, but most brands only protect against one type of UV radiation. Different brands use different chemical formulations. Commonly used chemicals are salicylates and para-aminobenzoic acid (PABA).
|SPF: Choose a sunscreen with a high SPF rating so that you can use it under all weather conditions. SPF 15 sunscreens can work for mild morning or late afternoon sunlight, but you may need an SPF of 30 or higher when staying out in midday. Choose a higher SPF for children or those with sensitive skin.|
UV protection: Choose a sunscreen that blocks both UVA and UVB rays. Look for those labeled “UV 400” -- this means that they absorb frequencies of up to 400 nanometers, which includes both types.
Waterproof: Choose a sunscreen that will not wash off when you sweat or enter the water. Waterproof sunscreens stay on longer, so you will not need to reapply frequently. These are usually labeled “waterproof” or “sports formula.”