Enough Sunscreen?
Most people don't use enough sunscreen. The average adult needs at least one ounce (the amount held by a shot glass) of sunscreen to adequately coat the body.
Also important: If you plan to be in the sun for more than 20 minutes (no matter what your skin type), use broad-spectrum sunscreen with a sun-protection factor (SPF) of 15 or higher that blocks both ultraviolet A (UVA) and ultraviolet B (UVB) rays...reapply it every two hours (even on cloudy days, year-round) to all exposed areas, including your ears, hands—and even your fingernails. Skin cancer also can occur on the scalp, so wear a wide-brimmed hat.