Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.
See all posts »When it comes to sun (ultraviolet radiation, or “UVR”) exposure, there is no such thing as a “safe tan.” Sunburn, skin aging (including age spots and leathery skin), wrinkles, and skin cancers are excellent reasons to seek protection from harmful rays and to minimize ultraviolet exposure when recreating in the outdoors. As an avid skier, fisherman, and hiker, I can attest to how difficult it is to avoid the sun, and how important it is to protect my skin. I have suffered numerous sunburns, I’m getting older, my forehead has not been smoothed by Botox, and I have had a few pre-cancerous lesions frozen with liquid nitrogen by my dermatologist or carved out of my body by a plastic surgeon. Had I used sunscreens properly, particularly in my youth, I could have avoided most of these interventions.
Suncreens come in liquid sprays, lotions, and creams. They either absorb UVR, act as barriers to it, or reflect light. People have different skin types, depending on their tendency to burn or tan, but they all need protection. The “sun protection factor,” or SPF, of a particular sunscreen, indicates the degree of protection. For example, a sunscreen with SPF 15 confers protection such that it would require 15 times the UVR exposure to produce a sunburn in a person with protected skin as opposed to unprotected (by the sunscreen) skin. This assumes a liberal and complete application, which rarely occurs. Therefore, to be safe, use a sunscreen of at least SPF 30, and reapply it at intervals of no more than every 3 to 4 hours. If you are sweating or swimming, you need to reapply more often.
