Sun Facts 3: Sunscreen

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So we all know that we should be using sunscreen on a daily basis by now, right?  But which sunscreen are you using, and are you using it correctly?  This is a bit more complex than it seems, and although choosing a higher factor will offer you more protection from the sun there are a few things you need to know when selecting your sunscreen and when applying it too.

What does SPF mean?  Okay, so you know SPF stands for Sun Protection Factor, and that the higher the SPF the more protection.  But it might interest you to know what SPF actually means:  Essentially when a manufacturer makes a sunscreen they gather 20 people with fair or sun-sensitive skin.  They then expose them to UVB and carefully time how long it takes for them to burn, which is quantified by a degree of reddening of the skin.  Once they know how quickly this person’s skin would burn with no protection, they apply their product to a part of the guinea pigs body that has not yet burnt in a thickness of 2mg/cm2 and expose this area to UVB once again and time how long it takes for the skin to burn.  The time it takes to burn with sunscreen is then divided by the time it takes to burn without sunscreen and the resulting number is averaged amongst the 20 guinea pigs, rounded down to the nearest 5 and slapped on the bottle!

After all of that the take home message is that the SPF number you see on your product means that you should take that many times longer to burn than you would have without the product.  So if you would have taken 10 minutes to burn then by applying SPF 15 you should now take 150 minutes to burn, if you apply the product correctly.

This means you should choose your products based on your skin colour or on the Fitzpatrick scale rather than on how much you want to tan.  No matter your skin colour you should be using an SPF daily, but in a black person or a Fitzpatrick VI skin colour an SPF15 may be sufficient, where if you are below a Fitzpatrick III you should really be considering using an SPF50, and certainly nothing lower than an SPF30.  Anything with an SPF less than 15 should honestly (in my opinion) be considered moisturizer and not sun protection, no matter your skin colour.

Applying enough product to get the advertised SPF out of it is your next challenge.  2mg/cm2 equates to about 1,25ml or ¼ of a teaspoon for your face alone, and if you’re at the beach you will need about 30ml for one application to your body.  That means that if you have separate sunscreens for your face and body, and you are applying your facial sunscreen once daily (as you should be, and twice daily minimum if you’re actually in the sun) your average 50ml of facial sunscreen should only last you 40 days.  You should be buying at least 9 tubes of facial sunscreen a year.  Are you?  If you aren’t, but you are using your SPF daily then this means that you are using too little and aren’t getting the advertised SPF out of your product.  Use more.

This also means that an average 100ml of body sunscreen should really only last you one or 2 beach days.  If you’re sweating or swimming you should be reapplying , and ideally you should reapply your sunscreen every 2 hours when you are in the sun anyway, so 100ml will give you 3 and 1/3 applications if you want to get the stated SPF out of the product…is your mind boggled yet?

SPF only refers to UVB, the burning UV, not UVA the aging UV.  There is no equivalent rating scale for UVA, but what you need to be looking for is a label that states that the product offers both UVA and UVB protection, and ingredients like zinc oxide and titanium dioxide which are physical barriers to UVA rays.  Unfortunately despite these ingredients there is measurement of how long these ingredients protect you for…best to just reapply as frequently as you can!

There are other factors to consider too.  Despite using a good sunscreen, you also need to be aware of other factors that can render your skin more vulnerable to the sun.  Certain antibiotics and products that contain Vitamin A will sensitize your skin to the sun and cause it to burn more easily.  Sweating or swimming can easily wash carefully applied sunscreen off your skin leaving you with uneven protection or no protection at all.  Applying your sunscreen unevenly will also leave you more vulnerable in certain parts, and who of us can’t attest to having had a dodgy hand-print burned onto our backs by accident?  If you have fair skin or a family history of skin cancer you need to be more careful than your friends too since you may be at higher risk for skin cancer.  On the flip side using sun-protective antioxidants will give your skin a bit more resilience against the sun (but NEVER enough that you don’t need to be using sunscreen at all times!).

Using daily sunscreen is never a decision you will regret, that we can absolutely promise you, and if you’re going to do it you may as well do it right!  Relying on the SPF in your make up alone is clearly not going to do the trick since most BB creams or foundations offer only SPF 15 – 25, and unless you’re really layering it on you’re probably not using enough of this to even get half of the advertised SPF out of it.  A healthy bronzed glow looks great, but we think it looks just as great coming out of a self-tan bottle or a bronzer compact and choosing that option will ensure you look fabulous for a whole lot longer than you would if you chose the sun tanning option.

We hope this information helps you to make wise choices this summer!  For more information on how to erase existing sun damage or on which sunscreens we recommend send us an email on and to find out more interesting facts about the sun and your skin read our previous posts: Sun Facts 1 & Sun Facts 2.


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