Decoding SPF: Everything You Need to Know About Sunscreen Today

Decoding SPF: Everything You Need to Know About Sunscreen Today

If you listen to any celebrity or “insider” interview about how they maintain great skin, they all say the same thing: sunscreen. Apply sunscreen every day, without fail.

I mean - we think that their “secret” probably also has to do with the weekly facials and major spa treatments, but there is definitely something to this sunscreen stuff.

Why? Sunscreen helps protect against UV rays, one of the most significant causes of free radical damage and aging, tired skin.

Sounds great - but there’s still a lot of confusion about sunscreen, including what types to use, what SPF is necessary, and more. Here’s what you need to know.

Understanding Sun and Skin Damage

sunscreen skincare eight saints

First thing’s first: not all SPF was created equal.

Normal, standard SPF (Sun Protection Factor) is actually a measure of how long sunscreen will protect you against ultraviolet (UV) B rays only. For example, SPF 15 means it will take 15 times longer for the skin to redden with the product on than without it.

UVB Rays

UVB rays are the main cause of reddening and sunburn, and they tend to damage the outermost layers of the skin. This is where most forms of skin cancer occur, and most of them are linked to sun accumulation over the years. Melanoma, on the other hand, is thought to be caused by brief, intense exposures, such as a blistering sunburn.

UVA Rays

But UVB rays are not the only rays you should be concerned about.

There are also UVA rays.UVA rays are longer than UVB, and they can reach the skin’s dermal layer (deeper down) damaging collagen and elastic tissue. This is also where the cells that stimulate skin darkening are found, meaning that UVA rays are considered the dominant tanning rays.

Though many people still think a tan looks healthy, it’s actually a sign of DNA damage. The skin darkens in an attempt to prevent further injury, which can lead to cell mutations that trigger skin cancer. That’s why UVA rays are known as the aging rays.

The point? You should be concerned about bothUVA and UVB rays. That means you need a “Broad Spectrum” sunscreen.These formulas contain a combination of ingredients known to protect skin against both types of UV rays.

These could be chemical sunscreens, physical sunscreens, or a combination.

Here’ what you should know about each type.

Types of Sunscreen

Chemical Sunscreens

Chemical sunscreens - which use active ingredients like avobenzone, oxybenzone, octinoxate and helioplex - work by absorbing UV rays. They’re usually more popular because they feel lighter and look and smell less noticeable on the skin.

Physical Sunscreens

Physical sunscreens, otherwise known as mineral sunscreens, contain active ingredients like titanium dioxide and zinc oxide. They reflect or scatter UV radiation and they’re considered to be more resistant to sweating and swimming. That said, they can feel heavier and look more noticeable on the skin.

Sunscreen Ingredients to Avoid

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Oxybenzone was banned in Hawaiibecause it’s shown to harm coral reefs and sea life. Plus, according to the Environmental Working Group (EWG), it’s a form of synthetic estrogen that can disrupt your hormones.

In its 2018 review of sunscreen ingredients, the EWG actually found oxybenzone to be the most troubling ingredient available.


Like oxybenzone, octinoxate is also banned in Hawaii. It’s also been shown to cause skin allergies - and, in many animal studies, it was found to have negative effects on the reproductive system and the thyroid.


This ingredient doesn’t cause hormone disruption, but it has been found to cause significant skin irritation. On top of that, it’s not sun-stable, which means that it has to be mixed with possibly toxic stabilizers to be used in sunscreen formulas. Not ideal either.

Retinyl Palmitate

This is a form of Vitamin A - which, when ingested, is a good thing. Vitamin A is a powerful antioxidant, and eating vitamin A-rich foods has been shown to protect the skin and combat free radical damage.

When applied topically and exposed to the sun, though, retinyl palmitate can actually cause free radicals to form,aka encourage damage to the skin.

Top Things to Look For

Look for sunscreens that offer:

  • SPF 30 or greater:SPF 15 is only known to filter out about 93% of the sun’s UVB’s rays, while SPF 30 can protect against 97% - which is why the AAD recommends using an SPF 30 or higher. Keep in mind, though, that no sunscreen will provide you with 100% protection, which is why hats and protective clothing are also a great idea.
  • Broad-spectrum protection:As we mentioned, broad-spectrum sunscreen protects against both UVA and UVB rays.
  • Water-resistance:If you're going to be exercising or in the water, it's worth getting a sunscreen that’s resistant to water and sweat. But understand what this really means. The FDA defines water-resistant sunscreen as meaning that the SPF level stays effective after 40 minutes in the water. Very water-resistant means it holds after 80 minutes of swimming. These sunscreens are in no way water-proof, so you'll need to reapply them regularly if you're taking a dip.
  • The right formulation for your skin type:Many sunscreens are made to specifically help those with dry, oily or sensitive skin. People with dry skin should look for ingredients like glycerin, lanolin, oils, silicones (like dimethicone) and aloe, and avoid sunscreen sprays or gels with alcohol. For oily skin, lightweight or gel lotions with ingredients like silica or isododecane are best, while sensitive-skinned people should look for hypoallergenic, fragrance-free formulas.

Overall, the EWG rates mineral sunscreens higher than chemical sunscreens, mainly because there is little evidence that these go through the skin barrier and are absorbed into your body or bloodstream, so you may want to opt for a mineral choice.

Look specifically, for titanium dioxide or zinc oxide.

Don’t Forget to Reapply

Once applied, sunscreen only lasts so long on our skin. The sun's rays break down some sunscreens. Others clump and lose their effectiveness.

To continue protecting our skin from the sun when outdoors, we must reapply sunscreen:

  • Every 2 hours
  • After toweling off
  • When sweating
  • After being in the water

Let’s enjoy the sunny days ahead!