Sunscreen User's Guide

What you need to know about protecting your skin

June 11, 2013
Photograph by Jake Stangel
ong>Sun Protection Factor
A rating determined by the percentage of ultraviolet B rays (the kind that lead to sunburn) the product blocks and the amount of time it fends off a burn.

Every 2 Hours
The rate at which you should reapply sunscreen. Do it more often if you are sweating a lot.

Broad Spectrum
Blocks both UVB and UVA rays (the latter­ cause skin ­cancer and premature aging). Products that don’t block UVA, and ones with SPF below 15, must state they only prevent sunburn, says the FDA.

The SPF rating above which the FDA has found little evidence of better protection. In the future, it may be the highest number that the agency will allow printed on product labels.

In:Water Resistant” (for either 40 or 80 minutes)

Out: The terms “waterproof,” “sweatproof,” and “sunblock.” New FDA guidelines ban these from labels.

Neck: The place most cyclists forget to PUT SUNSCREEN (the back of it, in particular)

20: Number of minutes dermatologists recommend letting sunscreen dry before you head outside

Slather Guide
1 tablespoon for: face, head, and neck
2 tablespoons: both arms
4 tablespoons: torso (front and back), both legs (more if you don’t shave)

Source: Vince DeLeo, MD, dermatology chair at St. Luke’s/Roosevelt and Beth Israel Medical Centers in New York City