Living in Houston, we’re all exposed to a lot of sun. The sun’s ultraviolet rays are the culprits, penetrating the skin and damaged its cells, leading to skin aging and wrinkling, and various skin cancers.
We all know that the best thing would be to never go outdoors, unless we are dressed like a mummy. But with our warm weather in Texas, who wants to do that?
So, we all apply sunscreen. But what do you really know about sunscreen and how it protects, or doesn’t protect, you? Here’s some info.
Sun protection factor (SPF) and UV radiation
Since the advent of modern sunscreens (if you’re in your 50s, you may remember one of the first sunscreens, Pre-Sun), a sunscreen’s efficacy has been measured by its sun protection factor, commonly known by its acronym, SPF. SPF is not really a measure of protection; instead it’s like a stopwatch. SPF is simply a measure of how long it will take for ultraviolet B (UVB) rays to redden your skin compared to having no sunscreen on. For instance, SPF 15 means that it will take 15 times longer with sunscreen on than without. Why does it use the UVB rays? Those are the rays that cause sunburn because they penetrate only the epidermis, the surface layer of the skin.
As for amount of UVB protection, an SPF 15 sunscreen screens 93 percent of the sun’s UVB rays; SPF 30 protects against 97 percent; and SPF 50 protects against 98 percent. The U.S. Department of Health and Human Services recommends only SPF 15 and higher for providing adequate protection.
But scientists now say UVA rays, which penetrate far more deeply, into the dermis layer of the skin, also cause skin damage and skin cancer. Because they penetrate more deeply, UVA rays are thought to actually cause more wrinkles and creases in the skin.
So, you need a sunscreen that protects against both UVA and UVB. To do this, look for a sunscreen with at least SPF 15, plus some combination of the following UVA-screening ingredients: avobenzone, ecamsule, oxybenzone, titanium dioxide, and zinc oxide. When you see a label that says broad spectrum or multi spectrum or UVA/UVB these indicate that some UVA protection is provided. However, there isn’t a measure of how much protection these terms denote.
How do sunscreens work?
There is a misperception about how sunscreens work. They aren’t actually a “screen” as you would think of it, simply blocking the sun’s rays. Sunscreens really are more like a mirror. The ingredients in sunscreens form a thin, protective film on the surface of the skin and absorb the UVA radiation before it penetrates the skin. The “sunscreens” are actually physically rejecting the sun, meaning that their insoluble particles reflect the UV rays back off the skin. The FDA has approved 17 active ingredients for use in sunscreens.
Unfortunately, no matter how much you know about UVA rays and sunscreen, your skin will still suffer sun damage. That’s where Dr. Kronberg comes in. She has extensive experience diagnosing and treating sun damage, whether it is skin cancer or less extreme damage. Be sure to have your skin checked at least once yearly because where we live the sun just keeps on keeping on. Call us for an appointment, 713-771-8941.