Test Your Knowledge

Sunscreen is a topical (applied to skin surface) product used to protect the skin from exposure to the sun’s ultraviolet (UV) radiation. It is available in a number of forms including lotions, gels, ointments, creams, wax sticks and sprays.

There are three forms of ultraviolet rays – ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). UVB rays are short wavelengths of UV light that reach the epidermis (the outer layer of skin). UVA rays are longer wavelengths of UV light that penetrate the dermis (the second layer of skin).

Exposure to the sun’s UVA and UVB rays can lead to sunburn, skin cancer (melanoma and nonmelanoma), premature aging of the skin and a number of other complications.

People do not need to protect themselves from UVC rays because they are completely absorbed by the ozone layer (the protective layer in the earth’s atmosphere) and never reach the surface of the earth.

Chemical sunscreen and physical sunscreen are the two main types of sunscreen. Chemical sunscreens absorb UV rays whereas physical sunscreens absorb, block, reflect or scatter the sun’s UV rays away from the skin.

Although some people burn more easily than others, everyone should use sunscreen any time they are going to be exposed to the sun for 10 minutes or longer. It should be applied to dry skin about 20 to 30 minutes before heading outdoors.

Enough sunscreen should be used to completely cover all areas of exposed skin, including the eyelids, nose, ears, neck, hands and feet. It is also important for people to frequently reapply their sunscreen because it can be washed off, rubbed off or sweat off. In general, sunscreen should be reapplied at least every two hours. Sunscreens labeled as waterproof or water-resistant also require frequent reapplication. All forms of sunscreen, including those labeled as waterproof, should be reapplied immediately after getting out of water.  

The American Academy of Dermatology (AAD) recommends that all people, regardless of their skin color or type, use a broad-spectrum sunscreen (protects against UVA and UVB rays) with a sun protection factor (SPF) of at least 15. SPF is a number assigned to sunscreen to indicate the product’s ability to protect from UV rays. The higher a sunscreen’s SPF, the greater protection it provides. The AAD also suggests the product be used year-round, regardless of season or weather.

Sunscreen does not provide complete protection from the sun’s harmful UV rays. When used properly, however, it does greatly reduce the effects.