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    Top Four Facts about Sunscreen

    Woman applying sunscreen
    SACRAMENTO, Calif., June 17, 2009 - You already know that too much sun can be deadly – but how much do you really know about sunscreen? Catherine Lenz, PA with Sutter Medical Group shares the top five facts (and more) about sunscreen that you may not know.


    1. The SPF (sunscreen protection factor) number explains two things

    How long you can stay in the sun before burning
    The formula is unique to each individual. [X] Minutes (number of minutes you can typically can stay in the sun for 10 minutes before turning pink) x [Y] (SPF rating) = how long you can stay in the sun.

    For example, if you can typically stay in the sun 10 minutes then a sunscreen with an SPF of 15 will allow you to stay in the sun for approximately 2 ½ hours. 10 (minutes) x 15 (SPF) = 150 minutes, or 2 ½ hours.

    How well it filters the sun’s harmful rays
    SPF 2 blocks about 50 percent of UVB rays.
    SPF 10 blocks about 85 percent of UVB rays
    SPF 15 blocks about 95 percent of UVB rays.
    SPF 30 blocks about 97 percent of UVB rays.

    An SPF that's higher than 30 does not provide any additional UV protection, it only allows you to spend a longer time in the sun without burning.

    2. There is no such thing as a truly waterproof sunscreen

    You should reapply sunscreen at least every two hours and more often if you've been swimming or sweating

    3. Apply liberally and early

    It’s best to apply about one ounce of sunscreen per body part – enough to fill a small shot glass – at least 15 to 20 minutes before sun exposure. It needs time to spread over and into the skin

    4. Altitude increases the sun’s potency

    For every 1,000-foot increase in altitude, the sun's potency increases.


    Catherine Lenz shares even more interesting facts about sunscreen.
    audio icon Look for a sunscreen that contains specific ingredients (MP3)
    audio icon Should sunscreen be applied before or after your makeup? (MP3)
    audio icon Multiple sunscreens do not add up to one SPF number (MP3)
    audio icon Tips on how best to treat sunburn (MP3)
    audio icon How SPF works (MP3)
    audio icon How often you should apply sunscreen (MP3)

    Looking for a dermatologist?

    Sutter Health Media Line, (916) 286-6695