Skincare Essentials 302 – what does SPF mean?
For the last several weeks you have listened to me from my beautiful soapbox espousing the importance of wearing sunscreen. What? You haven’t seen my Instagram OR read my other blog posts?! Well here it is in a nutshell: you must wear sunscreen. All day, every day, no matter what. NO MATTER WHAT.
The dangers of sun exposure can cause all the most unpleasant things we are trying to prevent… at most skin cancer and at least premature aging, including pigmentation, sun spots, and the most hated of all…fine lines and wrinkles. Your first line of defense against all these things – SUNSCREEN!
In my blog, Essentials of Skincare: Sunscreen I gave you an overview:
- The importance of wearing it
- The goal of wearing it
- The harmful rays it protects against
- Tricks on applying it
- The various formulations sunscreen can be found, ie: cream, powder, setting spray, makeup, etc.
But the thing that is most confusing to people (me included) is what does the number on the bottle really represent?
Most of us are of the mind that bigger is better. So in the language of sun protection, SPF 100 should be infinitely better than SPF 15. Unfortunately, that is not true.
Remember science is always evolving, and research studies are constantly being done to assure the best protection while doing the least amount of harm to the skin.
So this is what science tells us in 2019.
SPF is an acronym for Sun Protection Factor, referring to the amount of time you can stay in the sun without getting sunburned.
This is a fluid measurement, meant as a guideline for “most” people not a rule for everyone. For example, I get very little sun exposure, so my mayonnaise colored skin can start to tan or burn within the 15 minutes it takes me to walk the dogs in the afternoon. Some skins may be even more susceptible if using a lot of exfoliating products.
Here’s the Math for SPF:
Confusing, right?! So I’m going to break it down for you in terms we can all understand.
Multiply the SPF number of your product by the length of time it takes for you to burn if you weren’t wearing sunscreen. Example: with an SPF 30 x 10 minutes of sun time = 300. 300 minutes divided by 60 minutes = 5 hours of sun protection without a sunburn.
Now we all know after spending 5 hours at the beach (and only applying sunscreen once) that we are sure to get a sunburn. So you can see why it’s important to reapply every 2 hours.
And for my melanin-rich friends out there, you may think that because your skin is a naturally darker pigment that you have leeway to skip the protection. This is not the case, you need sunscreen too. You must subscribe to the philosophy “better safe than sorry”.
Research and manufacturers of sunscreen tell us that SPF 15 can filter out about 93% of UVB rays while SPF 30 filters 97% of UVB rays. At this time, it’s not possible for any level of sunscreen to block 100% of UV rays.
It takes significantly more active ingredients just to eek out a tiny bit higher protection percentage. So to use an SPF 50 or 100 won’t necessarily give to that much more protection nor allow you to stay in the sun longer. But, it might trick you into a false sense of not needing to reapply. Hence why it’s so important to use the 2 hour re-application rule.
Tips to Stay Protected
For everyone, re-application is key to preventing damage to your skin. Use the “reapply every 2 hours” rule of thumb. That is how long manufacturers “guarantee” the product stays active to get the right amount of sun protection.
Apply liberally, don’t skimp. Whether you are using a lotion, cream or spray, the recommended amount is 1oz (that’s about a full shot glass) of product to cover your entire body. When reapplying you must use another 1 oz to continue to be properly protected. This ensures replacing the product that may have worn off, sweated off, rubbed off, or swam off. Yes, if you are exposed to the sun for most of the day you will go through a lot of sunscreen.
How much is 1oz for spray sunscreen? Since you’re not going spray your sunscreen into a shot glass to measure it out, spray enough until your skin glistens. If your spray bottle is 6 ounces, you should have 6 applications, if it’s 8 oz you’ll get 8 applications, you get the picture.
Clearly, we can see there is something amiss with SPF math.
Unfortunately, there’s not much research to explain why SPF 45, 50, 100 doesn’t give us significantly more protection (or why it exists at all. My only answer right now would be…marketing and consumerism. But as I mentioned earlier, science is ever evolving so perhaps more research needs to be done to sort out the best version of sunscreen protection.
Until that gets explained, continue to wear your sunscreen, at least SPF 15 for everyday use and SPF 30 for extended sun exposure.
Leave a comment below or email me with what questions you have about sunscreen!
Melissa, such a wealth of knowledge. Thanks for researching and sharing. You’re saving lots of skin!! And ultimately families. Don’t underestimate your efforts! xo
Lori,
Thank you so much for reading my blog post and for all your encouragement. I really appreciate it!
Mwah!
I really love your articles/blogs. I love how you write and that you wrote the way you talk. Thanks for writing about spf factor and how often to reapply. Ppl need to know that no matter what, we gotta reapply every two hours! How often you you reapply? I reup every hour
Thank you so much for your support. It means the world to me! I’m thrilled to know that you are enjoying my posts, yes it’s super important to reapply especially if one is going to be out in direct sunlight for an extended period of time. I reapply at least once after my initial application, I prefer to use shade, hats, and clothing to protect against the sun. I apply SPF to my face every day as part of my skincare routine, even if I’m going to workout. What sunscreen are you using when out for the day?