You're heading out the door for a day of fun in the sun with your family. You grab the sunscreen because you know a sun protection factor (SPF) of 30 is going to protect your exposed skin from getting sunburned.
But Dr. Dawn Davis, a Mayo Clinic dermatologist, says most people don't know that skin covered by clothing still can get sunburned.
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"Natural clothing without sun protective factors will have an SPF of approximately 1 to 4, based on how tight the weave is and how breathable the material is," Dr. Davis says. "So it actually does not give you that much sun protection."
But, she says, there are special types of clothing that will protect you.
The clothing industry has now allowed the integration of a weave of microfibers into certain clothes that allow it to have a UPF, ultraviolet protection factor, that's equivalent to SPF of sunscreen.
Dr. Davis says UPF is even calculated the same way SPF is.
It's the ratio of the number of minutes you can spend outdoors without developing redness to the skin with the clothing on versus without the clothing on.
"So if you can spend 50 minutes outdoors with a piece of clothing before developing mild redness versus 10 minutes without, you would have a protective factor of 50 over 10, which is a UPF of 5," Dr. Davis says.
So the next time you're shopping for clothes, check the tag to see if it lists the item's ultraviolet protection factor.