SPF: Unveiling the Meaning of the Mystery Number

— Have you ever diligently covered your body with a generous amount of sunscreen, then spent all day outdoors… only to find later that evening that you’ve gotten sunburned again? Then you think to yourself: Well, what the heck? I know I applied my sunscreen. Why the heck didn’t it work?

— Or maybe you’ve heard this from your favorite doctor or dermatologist: “It doesn’t really matter what the number is … just make sure you WEAR it.” What the heck does THAT mean, exactly?

Image result for sunburn meme

You think you know all there is to know about SPF … but do you really?

Let’s take a quick minute to unveil one of the greatest mysteries surrounding SPF…

SPF is the abbreviation for Sun Protection Factor.

In the US, SPF protects your skin from burning in the sun, or from the sun’s UVB rays. The SPF rating of a sunscreen indicates how long your skin is protected before you sunburn. This is important to remember, because it is specific to your individual skin type.

In other words, if you are fair-skinned, and you normally burn after 10 minutes of unprotected sun exposure, SPF 2 will give you two times that protection (2 x 10 minutes = 20 minutes) before your skin burns. With SPF 30, theoretically, you may stay in the sun 30 times longer than it would normally take you to sunburn.

So…. does this mean you’re OK for 300 minutes?

Actually, NO — it does NOT. (And this is the reason why many experts say “the ‘number’ doesn’t really matter…”)

No matter the “number,” your sunscreen is only good for about 2 hours of protection, especially if you are spending extended time outdoors, or have been sweating or swimming. What happens is that the sun’s rays mixed with your skin’s acid mantle (the protective substance on the outside of your skin that fights off bacteria and other bad stuff) will break down and diminish your initial layer of sunscreen over time. So you must reapply when spending time outside in the sun, or after swimming or sweating, at least every two hours.

I realize this isn’t always practical, but there are ways to help with reapplication. For example: start your day with a good layer (1 oz for full body coverage) of lotion sunscreen (if you’re indoors, choose SPF 30, if you are spending the day–or several hours– outside, choose SPF 50). If you need to reapply and lotion won’t work … try a spray or spritz-on sunscreen (but only use these as a second step, not for an initial layer), or try a powdered sunscreen. If you’re outdoors and wearing makeup, start with your layer of sunscreen lotion before you add your makeup (with sunscreen) so protection lasts a little longer.

May is Melanoma Awareness Month. Need a sunscreen recommendation? Contact me for several great choices available at Face Perfection.


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