If you wear sunscreen with 30 SPF, are you getting twice the protection than sunscreen with SPF 15?
The answer may surprise you: no.
The general assumption is the higher the SPF, the more protection you have. But that’s not how it works. An SPF of 30 filters out about 97% of UVB rays; SPF 15 filters out 93%.
The number on the sunscreen indicates how long you can safely stay in the sun without burning based on your Maximum Erythema Dose. That’s a scientific way of saying you need to know how long it takes for your unprotected skin to turn pink.
If you’re fair, it may only take 10 minutes. Multiply that by the SPF and you have the number of safe sun minutes.
10 minutes x SPF 30=300 safe sun minutes
But there is a catch. Sunscreen wears off with wind, sweat, (even the “waterproof ones) and towel drying. That means your safe sun minutes get cut in half.
It’s best to re-apply every 2 hours. Don’t forget to wear a hat and lightweight clothing for added protection!
“I got a sunburn and I wore SPF 30 sunscreen. I don’t get it.”
That’s a frequent complaint from sun-loving clients that also want to protect their skin.
So what’s going on here? Did your SPF let you down? The problem is that SPF’s are greatly misunderstood. We expect a whole lot from this sun protector, but we aren’t willing to give much in return!
It all starts with this:
The SPF number indicates the amount of time you can stay in the sun without burning versus how long you could stay in the sun without sunscreen and without burning.
For example, an SPF 30 sunscreen allows you to stay outside 30 times longer than if you weren’t wearing sunscreen. But that’s only half of the truth!
What’s not commonly understood is the “Maximum Erythema Dose,” which simply means the point at which your skin flushes slightly pink while exposed to UV rays.
Obviously, it’s different for everyone. Very fair skinned people may start to pink up after 10 minutes in the sun. Darker skin complexions may take up to an hour.
Here’s a look at how the formula works for both skin types:
Fair Skin: SPF 30 x 10 minutes= 300 sun safe minutes
Darker Skin: SPF 30 x 60 minutes=900 sun safe minutes
The catch? Sweating, swimming, and rubbing off the sunscreen! For each of these, cut the sun protection factor in HALF.
Your sunscreen does work but you must re-apply frequently, preferably every 2 hours. Better yet, get out of the sun until tomorrow!
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