Science, Tech & Environment

Surprise! Sunscreen is only effective if you actually use it

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Do you use your sunscreen properly? Do you use it at all? Well, you should.

Ahhh ... summer. Backyard grilling, trips to the beach, sailing on the lake — and the familiar scent of a nice, finely-aged SPF 30 sunscreen.

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(This story is based on a radio interview. Listen to the full interview.)

Almost everybody knows they're supposed to use sunscreen, but not everybody does — and those who do use it often use it incorrectly, either by applying too little or not applying it often enough.

Don’t stop reading just because this sounds like a lecture from your mother — this really is good for you. Scientists like James SaNogueira say people who plan to be out in the sun need to be smart about protecting their skin. 

SaNogueria knows it as well as anyone: He's the senior director of skincare research and development at Energizer Holdings, the company that makes iconic sunscreen brands like Hawaiian Tropic and Banana Boat. And he wants people to be aware of the science that can protect them. There are some basic rules: 

1. Use More

“Sunscreen efficacy is measured based on a certain amount of sunscreen put on a certain area when the test is done,” he explains. “The test is done using essentially a specialized lightbulb [with] all kinds of filters.” But he emphasizes that lightbulbs are not the sun. The sun doesn’t have filters.

What’s more, he says: “Consumers use less than one-half of the amount that’s used in the test. Therefore, if someone is putting on an SPF 50 and using less than half the [tested] amount, they're going to get less than half the SPF.”

2. Get the SPF right

SPF means “sun protection factor,” but it’s more accurate to call it “sunburn protection factor,” SaNogueira says. If you don’t burn, sunscreen can be used to prevent getting a tan, because tanning is a sign of skin damage.

“If someone wants to just avoid burning, they use a lower SPF; if you want to avoid broader damage, or more chronic damage, or acute damage, then you use a higher SPF,” SaNogueira says.

SaNogueira says sunscreen typically contains about 17 active ingredients that work by absorbing the rays that come from the sun.

“The UV (ultraviolet) energy coming from the sun is expressed as particles — photons — that are traveling at the speed of light," he says. "When they get here, they hit your skin — and the sunscreen absorbs that energy and dissipates it so that it doesn't penetrate into your skin.” The different SPF numbers on commercial products are variations of the amounts and the combinations of these ingredients.

SaNogueira notes that the FDA no longer allows the industry to use the term “sun block.” “We don't want to give the idea that [sunscreen] is blocking a hundred percent,” SaNogueira says. “Percentages is a bad game to play anyway, because there's a lot of sunlight, and it's always there.” 

3. Protect against both kinds of UV rays 

UV-B are the rays that burn, or turn your skin pink and cause skin to blister. UV-A rays are more energetic and longer wavelengths that penetrate the skin. Over time, UV-A rays cause damage below the top layer of skin, which starts to break down the proteins and elastins in the skin. This is what leads to wrinkles, ‘leathering,’ and even skin cancer.

So it’s crucial, SaNogueira says, to use sunscreen that provides protection from both UV-A and UV-B rays.

4. Know the kinds of sunscreen — and pick the right one

Here's a new wrinkle (no pun intended): Consumer Reports is now advising sunscreen users to stop using spray sunscreen on children based on an ongoing investigation by the FDA into its potential hazards. So it's best to stick with the lotions and creams — even if your kids will hate you for it. 

Some people have expressed concern that applying too much sunscreen reduces the body’s ability to produce vitamin D. SaNogueira says while vitamin D deficiency is fairly wide-spread, sunscreen is not the culprit. 

“If you talk to dermatologists or other healthcare professionals, they’re clearly saying that the trade-off is more than worth it to use sunscreens,” he says. “If you find that your vitamin D level is too low, you [can] supplement it through a proper diet — eating fish, eggs, and (in the US) fortified milk.” 

So, how do we know when we are applying the right kind and the right amount of sunscreen?

First, consider your skin type, SaNogueira says. If you’re blue-eyed with fair hair and you know you burn easily, be conservative: use a higher SPF and apply it liberally and often. A good amount is about 1 ounce — the size of a shot glass — each time you apply it.

Second, ask yourself what your objective is and what outdoor activities you are doing. Are you trying to prevent sunburn? Are you trying to prevent long-term damage and melanoma? Are you in or around water? Are you perspiring a lot?

5. I didn't have time for all of that

The bottom line? There’s definitely a benefit to the higher SPF’s; always use a broad-spectrum sunscreen that blocks both UV-A and UV-B rays; and apply it properly.

And don’t forget to have fun. It’s summer, after all.

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