Sunlight: It's not that good for you
28 May 2013
I went for a quick walk up Carrock Fell at the weekend and got a bit burnt on the back of my neck. I'm not complaining, I'm just saying. I have bluey-white Cumbrian skin so I put on plenty of sun tan cream but still the deadly rays got through. How could this have possibly happened? What was the point of sunscreen if it didnt screen me from the sun for a measly three hours? I began to ask some serious questions.
Questions like - what is sunlight and why does it hate me? How can I protect myself? Why did I ever moan about the rain?
|Firstly, what is sunlight?|
I dont fancy going into too much detail here (because I dont know) so for our purposes sunlight is divided into three types of ultraviolet light:
UVA penetrates deeply into the skin and can cause cancer and premature aging
UVB - involved in tanning and burning of the skin
UVC - completely absorbed by the earths atmosphere
|Why does it hate me?|
Rest assured its nothing personal. Sunburn is caused by UVB radiation damaging molecules in your skin, most importantly your DNA. Your body doesnt like anything messing with your DNA so it takes measures to protect you. A bit of inflammation, redness and pain should be enough to tell you to get the hell out of the sun.
But what if you cant? What if youre at the top of Carrock Fell?
|How can I protect myself?|
Now were getting to the point. Sunscreen has clever chemicals that absorb and reflect UV light to varying degrees depending on the Sun Protection Factor (SPF). Sunburn is caused by UVB light and the SPF is a measure of how much UVB is absorbed or reflected by the sunscreen (are you enjoying the acronyms?).
A SPF of 15 will filter out 93% UVB light.
A SPF of 30 will filter out 96% UVB light.
To put it in a more useful way, if you normally stay out in the sun for 15 minutes before burning and you put on lotion with a SPF of 15, you can multiply your exposure time by 15 and stay out for 225 minutes (3.75 hours). SPF is a multiplication factor.
But wait, I put on SPF 30 and was only out for 3 hours? That should have lasted 7.5 hours, whats going on?
The 3.75 and 7.5 hours duration figures are codswallop. There are other factors involved that change the effectiveness of the cream, mainly rubbing, sweating and scratching. I was doing all of these on Carrock Fell. If you rub the cream off its not going to work properly, if it isnt water resistant and youre sweating the protection wont be as good, if youre Mr Scratchy same thing.
Because of this, most manufacturers recommend reapplying sun cream every 2 hours, more if youre swimming or sweating.
|But what about UVA light?|
As you will have read earlier UVA penetrates deeply into the skin and can cause cancer and premature aging. Ouch, thats not something you want to bring back from a hike. The SPF is nothing to do with UVA protection. To make sure the sunscreen also provides UVA protection, you need to look out for is this:
| If it has this symbol it means the product contains at the least the recommended minimum level of UVA protection. This is a must.|
You need sun cream (even in The Lake District). Ideally, you should go for SPF 15 or above with the UVA protection and, if youre sweaty, water resistance. At least every 2 hours reapply the cream.
The good news for us Cumbrians is, the bottle keeps until next year.
Thanks for reading.
Photo by: krishram27