There is one question that gets asked every summer: Does a really high SPF actually make a difference? You may be prone to reach for a sunscreen with SPF 30, while your friend prefers SPF 100 (and constantly reminds you that it is a better choice).
But is it? Some cult favorite sunscreens like Coola’s MakeUp Setting Spray or Supergoop!’s Unseen Sunscreen max out at SPF 30 and 40, respectively, so should we be looking for higher than that?
In theory, sunscreen with a higher SPF should offer you more protection. But in practice, it does not quite work that way. The concern dermatologists and other experts have is that using a higher SPF may create a false sense of security and people may feel justified spending more time in the sun.
In fact, the U.S. Food and Drug Administration — the agency has been reevaluating the safety of sunscreens this year — has even proposed to cap the SPF max at 60, which has received wide controversy.
What is SPF?
SPF stands for sun protection factor, and measures how long your sunscreen will protect you from ultraviolet (UV) B rays, which are the rays that cause skin burning and damage the epidermis, — the outer layer of the skin — where most of the common forms of skin cancer occur. The SPF number essentially tells you how long the sunscreen will protect you from UV rays. For example, using an SPF 15 sunscreen means you will take 15 times longer to burn compared to not using sunscreen at all.
But it gets tricky once you go beyond SPF 30. “In a laboratory setting, when you’re testing sunscreens when you go above an SPF 30, there doesn’t appear to be any additional benefit or very marginal benefit,” says Whitey Bowe, M.D., a board-certified dermatologist in New York City. According to both the Environmental Working Group (EWG) and the Skin Cancer Foundation, SPF 30 blocks about 97 percent of harmful UVB rays, SPF 50 blocks about 98 percent, and SPF 100 blocks about 99 percent. You would think that an SPF 100 would block twice as much as an SPF 50, right? That is not the case. Sun protection grows exponentially when SPF goes up to 30, then, growth is marginal. If anything, it is just that higher SPFs can be a little more forgiving, acting as a buffer for when we do not apply as well or as often as needed. These margins also play into the FDA’s proposed cap on SPF labeling — it is misleading that with SPF 100 you are completely clear of sun damage (you are not).
Higher SPFs can act as a buffer for when we do not apply as well or as often as needed.
Does the Number Matter?
In one study, participants applied SPF 50 to one side of their face, and SPF 100 to the other side before spending the day in the sunlight. The following day, when assessed for damage, researchers discovered that the side with SPF 50 was 11 times more likely to burn than the side with SPF 100. So, all in all, there is something to be said to higher SPF values when used in real life. Interestingly, most Japanese sunscreens have high SPF (somewhere between 35 and 50) as well as something called the PA factor, which is the measure of how much protection the sunscreen has against UVA rays. PA protection is measured in plus signs, not in numbers. So, it is common to see anything from PA+ to PA++++, the highest protection at the moment.
But what seems to matter more is the application. Essentially, when you use an SPF 30, you maybe only getting an SPF of 10, and when you use an SPF 50, you may actually be getting an SPF closer to 30.“In real life, people are more likely to use less sunscreen than they’re supposed to, and they’re less likely to reapply it as frequently as they’re supposed to,” says Bowe. “With sunscreens that have an SPF 50 or SPF 100, they actually have more of a buffer, so you’re less prone to user error with a bit more room for mistakes.”
You should apply well and apply often — even if you do not burn, spending more time in the sun can still damage your skin and make you age faster thanks to the aging ray (UVA). UV rays are strongest between the hours of 10 a.m. and 4 p.m. when the sun is highest in the sky. With a higher UV index, you should reapply sunscreen more often. Bowe says that even though it might be unrealistic to tailor sunscreen application based on the UV index every day, there are apps for that!
But is it enough? While the FDA collects more data on the topic, the EWG recommends choosing sunscreens within the SPF 15-50 range and not simply relying on sunscreen. Bowe, on the other hand, recommends SPF 50+ if you are spending significant time outdoors, while at the same time making use of a hat, sunglasses, sun-protective clothing and seeking shade midday. It’s important to still use sunscreen indoors, too! And while you might reach for a higher SPF if you have a light skin tone and a lower SPF if you have a darker skin tone, the American Academy of Dermatology says SPF 30+ is beneficial for all.
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