Saturday 29 August 2015

SPF Forever

The summer is drawing to an end and if like me you live in a part of the country where summer happens for a week in May then you might be wondering why it is recommended that you wear a moisturiser with SPF protection all year round. Seems a bit excessive doesn't it. But don't pack any your SPF just yet!
Whitehaven harbour at sunset.
Image: Jennifer Carroll

Let me start by first explaining what SPF is and how it protects you.

UV rays from the sun are broken down into three categories: UV-A, UV-B and UV-C.

UV-C is made up of the shortest UV wavelengths and is the most damaging. Luckily for us all UV-C rays from the sun are absorbed by the Earth's atmosphere. Good ol' planet, looking out for us. The only way you will experience UV-C on Earth is from an artificial source, like a UV lamp, uses of which include killing germs...

UV-A is made up of the longest UV wavelengths and accounts for most of the UV radiation that reaches the Earth's surface. It also penetrates deepest into the skin and is responsible for the tanning effect. UV-A, however is also responsible for ageing the skin, causing wrinkles and can cause lasting damage to your skin.

UV-B is the most biologically active type of UV radiation, it sits in the Goldilocks zone for interaction with human tissue. It can only reach into the top few layers of skin and is responsible for short term effects like sun burn as well as tanning. Like UV-A, UV-B exposure promotes ageing of the skin and can lead to the development of skin cancer.

SPF or sun protection factor is a measure of the creams ability to protect you from UV rays. It works as a multiplication factor. So if you wear factor fifteen your skin will withstand the sun fifteen times long than without before burning. This works in combination with your skin and its own defences against the sun; melanin is a chemical present in the skin which absorbs UV light in order to protect your skin cells.

FUN FACT: Melanin is the pigment found in human skin, hair and eyes and is responsible for their colour.

Sun creams are made up of a combination of organic and inorganic compounds which either absorb the UV rays like our natural melanin or reflect the UV rays away from the skin.

Gone are the Days of White Noses
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It is the inorganic part of the cream that gives it the characteristic white colour we know and love, but gone are the days of a thick white cream you can still see once applied to the skin. Titanium oxide or zinc oxide are the compounds responsible for this white colour, celebrated in creams like Zinka, made popular by lifeguard and professional athletes in the 80's, availablein a range of colours as well as white. Modern sun cream recipes now incorporate smaller, nano scale particles which do no scatter light as effectively as the larger metal oxide particles and hence appear transparent when applied to the skin.

The larger sized metal oxide particles reflect all light equally and so appears white on your skin. Whereas the nano particles create a layer that absorbs the UV light.

All Year Round
So far we have discussed the whats and hows, but now we shall have a look at the whys.

We all know that it is recommended we avoid the summer sun between 11am and 4pm, when its at its harshest and that's understandable. Who wants to feel like their skin is being fried like an egg? And sun cream protects us, so lets slather ourselves in it.

The case doesn't seem quite as strong for SPF during the winter, but we have to remember that the sun is ALWAYS shining. If you are out during the day you will be exposed to some amount of UV. For many of us in the UK, even though that light may reach us through a thick layer of cloud, it still gets to our skin. If you were going skiing you would take sun protection. Rays reflected from the snow increase your UV exposure. A it closer to home, UV reflected from puddles on the high street will also increase your exposure...

The effects of such exposure many not be as obvious as tanning during the summer, but all exposure adds up, leaving a lasting effect. So take the time to invest in an SPF moisturiser. Most come as a standard SPF-15 and apply about a tablespoon of moisturiser all over you face and neck area.

By Spigget (Own work) via Wikimedia Commons
[CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)
So protect your skin all year round and it will protect you. A T-shirt and hat aren't enough, we all have room for a little SPF in our lives.

Further reading:
  1.  Garnier sun protection adive with some interesting facts about your white T-shirt.
  2. Sustainable Nano has a great article about the use of nano particles in sun cream. Lot of interesting chemistry in there too. 

I cam across this video whilst doing my research for this post. Dr. Natalie talks about wearing an antioxidant, which can help to counteract the effect of skin exposure to UV rays, as well as some other interesting and intriguing skin care tips.




Dr Natalie's Top 5 alternative skin care tips...
Posted by Light Touch Clinic on Wednesday, July 22, 2015


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