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Ask Buck

Sun Exposure Up High

Do you need extra-strength sunscreen at high altitude?

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Question:

When you’re above 10,000 feet, is normal sunscreen adequate?

Submitted by – Stu, Pleasanton, California

Answer:

Some studies indicate that UV radiation increases by about 4 percent for every 1,000 feet you gain above sea level. Some studies suggest a higher percentage of increase. The main thing is that you do get quite a bit more UV exposure up high. However, people with medium- to light-brown skin color (most Caucasians, many Asians and Hispanics) usually get enough protection with a “normal” sunscreen of SPF 30—if they apply it before exposure and repeat applications a couple of times per day. People with very fair to fair skin are advised to use a sunblock (like zinc oxide or titanium dioxide), blocking out all UV radiation. Light-skinned people not only burn more easily, but they also develop more cases of skin cancer. In all cases, it is best to wear a brimmed hat and, of course, sunglasses that protect against all UV light. —Buck