It’s a handy little mnemonic, but there’s a lot more to it. In the spectrum of light waves, visible light is longer than UV light. Generally, the shorter the wave, the more energy it has…and the more trouble it has penetrating the atmosphere, or for that matter, skin. UVA waves are the longest type of UV light, and just shorter than visible light. Almost all UV light is in the UVA range. UVB rays come next. They’re stronger but less penetrating: indeed, the vast majority of UVB light gets trapped in the outer atmosphere. Thanks to ozone depletion, of course, a lot more gets through than in the past. UVC light is by far the strongest, most dangerous and shortest wavelength. Fortunately, it generally can’t get through the outer atmosphere.
So what do they do to our skin? UVA penetrates deeper into the skin than UVB light but doesn’t fry the surface like UVB light. Although less potent, UVA is more dangerous than UVB light in some respects. Its effects are not immediately visible and many sunscreens don’t do a good job of blocking it (the FDA has no labeling requirements in place to illustrate the degree of UVA protection…all those sunscreens that purport to offer UVA protection don’t have to give specifics). It’s like drinking spiked punch – without even realizing what’s happening, you can get yourself in trouble. UVA degrades elastin and collagen – the stuff that holds skin together and gives its pliability and smoothness. UVA light makes skin sag and wrinkle. Newer studies are also showing that it can cause skin cancer and degrade the skin’s barrier function. It deoxidizes corneocytes and impairs peptide functioning. It degrades corneodesmones, which compromises skin integrity, and can even affect our immune systems. Hopefully, the FDA’s proposals to establish a UVA metric will eventually take effect. Until then, tread carefully. Take a look at the EPA’s list of strong UVA blocks. And then take a look at Sana’s ingredients!
UVB light, on the other hand, wreaks more immediate damage at the skin’s surface but does not penetrate to the deeper levels (although it has its benefits, too). Since SPF is tied to UVB light, and because UVB leaves direct evidence on the skin, most sunscreens block UVB light.
One other tip – just like a marshmallow, don’t get too close to the flame! Your skin produces melanin in response to UVB light, but it takes several hours for the process to effectively kick in. Melanin is what makes you tan and helps protect you from UV rays and sunburn. So, if you’re going somewhere sunny, be especially careful the first day!
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