You’ve heard it from your mom since you were a kid: don’t forget your sunscreen! But why is sunscreen such an essential part of your daily skincare regimen? And what even is the difference between SPF 15 and SPF 50?? Is there a difference?? If you’re confused about SPF, join the club.
So, What Is SPF?
SPF stands for “sun protection factor
.” According to Kimberly Mallet, a research associate at the Penn State Prevention Research Center, a sun protection factor specifically indicates protection against ultraviolet B (UVB) rays that cause sunburn. Now, we know that ultraviolet a (UVA) radiation is also a huge factor in damaging the skin, but, as of now, there is no rating system for UVA radiation.
How Does It Work?
The Sun-protection factor system measures the length of time a sunscreen will protect your skin from burning from UVB rays, compared to how long your skin would take to burn without sunscreen protection. Let’s imagine you’re chilling by the pool, scrolling through your Insta feed, feeling lazy about your sunscreen, and your skin begins to burn after ten minutes in full sun with zero protection. If you’re wearing SPF 30, you are getting 30 times the protection against UVB rays compared to wearing no sunscreen at all.
But, Do I Really Have to Reapply?
Okay so I did the math and if I’m not going to burn for 300 minutes (5 hours), I only need one application of sunscreen for the whole day right? Sadly, that’s not gonna cut it. Mallet says we should apply sunscreen every one to two hours when outdoors. Even if a sunscreen says “sweatproof” or “waterproof,” we have to take these words with a grain of salt. For optimal protection, reapplication is the name of the game… Keep your enemies close, but keep your SPF Closer. When you reapply sunscreen, you are replacing what was worn off by swimming, sweating, or rubbing; you are not adding more hours of protection. Also, because people often don’t use enough sunscreen to begin with, (a shot glass aka two tablespoons of sunscreen to the face and body, or a a nickel-sized dollop to the face alone), reapplying becomes even more important. If you're using a spray, apply until an even sheen appears on the skin. The Skin Cancer Foundation says that it is also important to apply sunscreen at least thirty minutes before sun exposure in order to allow its ingredients to fully bind to the skin.
Mythbusting: The SPF Rating System
Okay but if I just apply a lot of SPF 100, I should be good to go right? Not quite. SPF 100 does NOT mean you are getting twice the protection of SPF 50 like you might assume. Anything over SPF 15 is going to do a perfectly good job blocking UVB rays—over 90% of them according to Mallet—so it actually doesn’t make a difference to use SPF 30 or SPF 100 if you are not reapplying every couple hours. And remember, Higher Sun Protection Factor numbers don't necessarily mean you are protected against UVA rays. Make sure that your sunscreen says “broad spectrum,” meaning that it protects you from both UVA and UVB damage.
Ultraviolet Rays: The Bonnie and Clyde of Skin Cancer Risk
We’ve mentioned ultraviolet rays—so what is the difference between UVAs and UVBs? The big bad UVB rays are what cause the actual reddening that we recognize as a sunburn. While UVA rays do not cause visible damage like UVBs, their damage is sneakier and deeper penetrating than UVB’s. According to the Skin Cancer Foundation
, UVA rays are what cause wrinkling, leathering and sagging. These guys contribute to photoaging, which is when your skin loses its youthful appearance which can lead to fine lines around the lips and age spots on the hands. They can also exacerbate the carcinogenic effects of UVB rays! To sum it up, UVB and UVA rays combine forces to make for a dangerous duo we need to protect our skin against.
Choosing Your Sunscreen
According to the Abramson Cancer Center at Penn Medicine, both physical and chemical sunscreen will provide adequate protection against both UVA and UVB rays (broad spectrum). Let’s look at the differences between your two options.
Chemical vs. Physical Sunblock
Physical sunscreen contains active mineral ingredients such as titanium dioxide or zinc oxide. Think of these minerals as physical shields that sit on top of your skin, deflecting UV rays away. Physical sunscreen protects against both UVA and UVB rays and tends to be better for sensitive or heat-activated skin (like rosacea and redness). If you have acne-prone skin, rosacea or generally sensitive skin, physical sunblock is a good call because it is less likely to irritate your skin or clog your pores. Unfortunately, physical sunblock tends to be white and thick, making it harder to blend into your skin or wear underneath makeup. Physical sunblock is also more likely to sweat off during physical exercise. Chemical sunscreen contains organic compounds like oxybenzone, octinoxate, octisalate, and avobenzone. These compounds create a chemical reaction by changing UV rays into heat and releasing it from the skin. Chemical sunscreen tends to be thinner than physical, making it easier to wear on a daily basis, especially if you have darker skin and you don’t want your sunscreen to leave a white cast. Unlike physical sunscreen, which is immediately effective upon application, chemical sunscreen takes about 20 minutes to kick in. Chemical sunscreen might cause more irritation or redness than physical sunscreen, so it is important to know what your own skin is prone to.
Now that we have a better understanding of what sunblock is and why it is so important, let’s talk about your new best friend in your morning routine. We all know how daunting the drugstore aisle can be, so we have provided a few of our favorite products. Mallet recommends a “broad-spectrum, water-resistant sunscreen that protects against both UVA and UVB rays.” Here are some options that fit this description that we love at here at Mirra:
1. ELTA MD UV Clear Broad-Spectrum SPF 46
You can find EltaMD sunblock in almost every dermatologist office in LA. Their UV Clear Broad-Spectrum SPF 46 is a serious fan favorite --- it contains lactic acid, niacinamide, Vitamin E, Zinc Oxide, and other antioxidants which protects your complexion while shielding you from shield harmful UVA and UVB rays. It's fragrance-free, hydrating, and as far as physical sunscreen goes, comes on very sheer.
2. Drunk Elephant
Umbra Sheer is a daily physical sunscreen by Drunk Elephant loaded with potent antioxidants like astaxanthin, grape juice extract, and sunflower shoot extract to help defend from free radicals and environmental aggressors. It's very difficult to formulate a physical sunblock without using chemical sunscreens or silicons, but Drunk Elephant has done just that. The only draw back is that it's a little "goopy," and takes about a minute to really absorb into skin. But, if you're in the market for a totally clean, physical SPF, this is your girl.
This Supergoop! original is the best chemical sunscreen we've come across. It's water-resistant, and also very
fast-absorbing. It's also the perfect balance of being both hydrating and lightweight. It's made with natural extracts of citrus, basil, and bois de rose, which contributes a beautiful scent you'll appreciate when slapping this bad boy on daily.