Sunscreen 101
School is back in session! Here is a little sunscreen 101:
UVA vs. UVB
There are two categories of ultraviolet light: A and B.
UVB wavelengths are shorter and primarily affect the keratinocytes in the top layer of the skin. Sunburn is caused by UVB rays injuring this top layer.
UVA rays are longer and can penetrate the melanocytes which are below the keratinocytes. Melanocytes produce melanin and cause the skin to darken. Activating these cells results in a suntan.
Collagen and elastin, which keep the skin elastic and plump, reside in the next layer down. UVA rays trigger the breakdown of those proteins, causing wrinkles as the skin loses its elasticity, as well as the thinning of skin, making blood vessels more visible.
What is a sunscreen?
Sunscreen is meant to block the UV rays from reaching and penetrating the skin. Chemical sunscreens absorb UV rays. Zinc, a mineral sunscreen, acts rather as a physical barrier, reflecting the ultraviolet light off the skin.
Sun protection factor, or SPF, refers to how well the sunscreen prevents a sunburn, but only applies to UVB protection. To have protection against, sunburn and advanced aging, you’ll need a “broad spectrum” sunscreen. There are just a few ingredients approved for use in the US that block UV — zinc oxide is the only effective mineral choice.
SPF 30 blocks 96.7% and SPF50 blocks 98% - a fractional difference. What matters more is the frequency of application. We recommend every 2 hours if out and about in the sun, and every 40 min if swimming or sweating.
A cute hat also helps too!
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