Start by following the lead of a group of skiers from Colorado and apply sunscreen frequently while outside, Rigel says. In a study of 105 skiers in Vail, Colo., Rigel and colleagues found that SPF 15 and SPF 30 sunscreens offered the same protection against sunburn. What made a difference, however, was how frequently the sunscreen was applied. A is for asymmetry. In healthy moles, one half of the mole will match the other half.
B is for border.
The border of moles should not be irregular. C is for color. Suspicious moles may have more than one color, such as black, tan, or brown and sometimes red, white, or blue. D is for diameter. A mole should be no larger than six millimeters, which is roughly the size of a pencil eraser.