Best Sunscreen: Are SPF Numbers Misleading?
- Posted on: Sep 14 2018
When looking for the best sunscreen (or “best sunblock”) you might think that an SPF protection of 60 is twice as good as SPF 30 sunscreen, right?
Nope. Logic fails us when it comes to this numbering system.
While it makes intuitive sense that choosing an SPF 60 over an SPF 30 would be the best sunscreen choice—offering the ability to go twice as long without reapplying—the truth is that SPF numbers don’t really add up that way. This numeric sunscreen language is not consumer-friendly.
In fact, these numbers are downright misleading. So here’s a ray-ality check.
SPF stands for “Sun Protection Factor” which theoretically refers to the amount of time you can stay in the sun without getting sunburned compared to going without sunblock. For instance, an SPF 15 would allow you to stay in the sun 15 times longer than you could without protection. So if you could tolerate the sun, unprotected, for 20 minutes before turning red, you should be able to stay out for 300 minutes, right?
It’s not that simple.
Truth in Sunscreen SPF Numbers
As you can see from the chart above, SPF numbers correlate more to the percentage of rays blocked than safe exposure time. And once you get past SPF 30, your UVB protection basically levels out. Nothing short of living in a dungeon truly offers you 100% protection.
- SPF 15 blocks about 93% of UVB rays
- SPF 30 blocks about 97% of UVB rays
- SPF 45+ blocks about 98% of UVB rays
Both The Skin Center, as well as most dermatologists, recommend that you use a product with an SPF 30 or above. Just don’t be fooled into thinking that an SPF 50 or 60+ product is superior.
The Skin Cancer Foundation points out that “there are problems with the SPF model: First, no sunscreen, regardless of strength, should be expected to stay effective longer than two hours without reapplication. Second, “reddening” of the skin is a reaction to UVB rays alone and tells you little about what UVA damage you may be getting. Plenty of damage can be done without the red flag of sunburn being raised.”
A sunscreen’s SPF protects against UVB (B for burning) rays only. UVA Rays are the more deeply penetrating, damaging rays—the rays that can cause melanoma and premature aging of the skin.There are additional factors (like fair skin, ethnicity, certain oral and topical medications, water and sweat, etc.) that impact how well you tolerate the sun.
Best Sunscreen for Both UVB & UVA Protection?
Since products labeled with an SPF number alone won’t protect you from most UVA rays, look for a “Broad Spectrum Sunscreen” containing a physical block such as zinc oxide and titanium dioxide.
So, what’s the Skin Center’s recommendation for the best sunscreen for the face? Or the overall Best Sunscreen 2013 offering both UVA and UVB protection?
We love that the newer broad spectrum formulas, such as SkinMedica DAILY PHYSICAL DEFENSE SPF 30+ and EltaMD UV CLEAR BROAD-SPECTRUM SPF 46 offer you the sheerest of sheer in oil-free, hypoallergenic sun protection that’s light enough to be worn under makeup. Elta’s UV CLEAR is also recommended for acne-prone skin.
Bottom Line: Use SPF 30+ and Reapply
Just because you apply sunscreen before you go out in the morning doesn’t mean you’ve done your job. Your morning sunscreen leaves you unprotected well before noon. Reapply. Reapply. Reapply.
Be strategic! The best way to stay vigilant is to keep your sunscreen where you’ll be visually reminded to reapply it. Have one handy by your make-up mirror, in your purse, in your car, by your front door. Don’t forget to pitch last year’s sunscreen since it has a limited shelf life.
SEE OUR BLOGS for more information on sunscreen, sun damage and recovery from sun damage:
- SUNSCREEN NEWS—Why SPF Alone Is Not Enough
- PHOTOAGING: Seeing is Believing
- SUN DAMAGE RECOVERY: PART 1 of 4
- SUN DAMAGE RECOVERY: PART 2 Understanding Hyperpigmentation
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