Brittany asks…Ok, I feel kind of stupid asking this because everyone else probably already know this but what exactly does SPF mean? I mean I know it stands for Sun (Solar?) Protecting Factor but what does that mean?
The Right Brain responds:
As far as we’re concerned, Brittany, there are no stupid questions. In fact, you raise a very good question because we think that a lot of people are unclear of the real answer. So, in today’s post we’ll spell out exactly what SPF means.
The ABCs of SPF
First of all, you were close on the meaning of the acronym. SPF actually stands for Sun Protection Factor. This factor is a measure of how much Ultraviolet, or UV, radiation it takes to burn your skin when it’s unprotected compared to how much it takes to burn it when it’s slathered in sunscreen. The higher the SPF value of your sunscreen, the more protection it offers from sunburn.
Now, here’s the tricky part. Many people think that SPF relates to how much time you can spend in the sun. In other words, if you can stay in the sun for 30 minutes before burning and you wear a sunscreen with an SPF of 10, you should be able to stay in the sun for 30 x 10 = 300 minutes or 5 hours before burning. Right? WRONG!
Why is it wrong? Because SPF doesn’t just relate to the duration of sun exposure – it relates to the amount of sun exposure. Time is one factor that contributes to the total exposure level but it’s not the ONLY factor. The intensity of the UV radiation also impacts the amount. For example, one hour of sunlight at 9:00 in the morning is equivalent to 15 minutes of sunlight at 1:00 in the afternoon. So if you’re only looking at how long you’re out in the sun you might drastically under estimate how much sun exposure you’re really getting. Geography is another factor: sunlight is more intense the closer you are to the equator. And weather is yet another consideration: even though you can get a sunburn on cloudy days, the effect of sunlight is generally more intense when the sky is clear.
The Beauty Brains bottom line
The SPF value of a product does NOT tell you how long you can stay out in the sun before you burn. It only tells you the relative difference between the level of protection provided by different products.
Source: FDA.gov
Do YOU have a favorite sunscreen? Leave a comment and share your thoughts with Brittany and the rest of the Beauty Brains community.
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So how do you know if you’re wearing enough SPF? I’m outside for about 30 minutes a day maximum… 15 minutes at 8 am and 15 at 4 PM – how much spf do I need?
I think there are three main reasons why you can’t just look at the SPF number and know how long you’ll last in the sun before burning: variable exposure, product application, and sunscreen stability. I think you covered the first point quite well. It’s important to note that the SPF number is generated with a product usage that’s MUCH higher than what most folks would actually apply to their skin. Also, product aesthetics do a lot to drive how much you use. One SPF 15 product can be really white and pasty while another is clear and light. The average person will tend to use a lot less of the first product and get a lot less protection, even though they’re labeled the same SPF. And aesthetics typically worsen as you go to increasing SPFs, so it’s hard to say that the SPF 30 product is going to offer 2x the protection. As far as stability goes, time isn’t factored into the SPF test and that’s a big deal since the sunscreen “actives” aren’t chemically stable. So the main thing is that if you know you’re going to be outside for longer than it normally takes to burn that you apply the product generously and reapply regularly.
@Kristy – this is hard to answer without knowing how easily you burn to begin with, but it sounds like even a minimal SPF product would be more than adequate for your exposure.
As the SPF factor goes on increasing the cream becomes more greasier and starts leaving behind a residue. mySkin.com has always suggested me sunscreens with SPF’s 15 or 30 and they work out for me well even though I’m out in the sun most of the day.
Hmm..this was an interesting article. I never really did know what SPF truly meant. I will keep this in mind as I head out in the sun this summer.
This was very interesting, thank you. I never really paid attention to what SPF meant, except to get the biggest number I could find and to re-apply according to the directions. I’m glad to see that many beauty websites (like this one) and companies are working so hard to educate people about too much sun exposure. I read at The Beauty Girl that Jergens is donating $1 to the Skin Cancer Foundation for every view of its video with Jane Krakowski to promote its self-tanning moisturizer. Good stuff.
http://thebeautygirl.com/?p=3233
I think it would also be relevant to add that SPF only refers to UVB. As we know, there is 3 kinds of UV rays: UVA (that penetrate the dermis and have long-term effect such as loss of elasticity, dark spots, premature aging, cancer), UVB (that penetrate the epidermis and cause the sun burn and cancer) and UVC (that are extremely destructive but thankfully all absorbed by the o-zone layer).
It was long though that UVB was the most dangerous among UVA and UVB. It causes the skin to burn and possibly to flake after a sunburn (which is, by the way, a “collective suicide” of your skin cells, their very last resort of preventing the apparition of a cancer or other destructive consequences). It was also though to be the only cause of skin cancer.
However, recent recerch has proven that UVA is equally (or even more) dangerous than UVB because is penetrates deeper into the skin, where more skin activities are taking place. UVA can lower immune system, decrease collagen and elastin production and cause the skin to age much faster.
Therefore, it is important to look for UVA blocking ingredients in your everyday sunscreen. And to wear sunscreen everyday. Actually, research has proven that using SPF 15 daily was more effective at preventing aging than using a higher SPF once in a while.