Six important questions about sun cream
It's Summer again, which means that shops are now lining their shelves with bottles of sun cream in every shape and size. With skin cancer being the most common cancer in the UK, protecting yourself from harmful UV rays from the sun is becoming more and more important1. With that in mind, we've put together the following article to answer some important questions about sun cream and why we should all be wearing it!
What are UVA and UVB rays?
The sun emits two types of light - visible light which we can see, and ultra violet light which is invisible to the naked eye. Ultraviolet (UV) rays, come in three forms - UVA, UVB, and UVC. UVC rays are mostly absorbed by the ozone layer, however both UVA and UVB rays penetrate our atmosphere and are responsible for sun damage such as sunburn and aging2.
UVA rays make up approximately 95% of the radiation in our atmosphere. They are present during nearly all hours of daylight, even in the shade, and can get through clouds and glass. Though more prevalent than UVB radiation, UVA rays are weaker. That doesn't mean they don't pose a threat however. UVA rays penetrate our skin deeper than UVB rays. They are responsible for tanning and aging, and play a part in the development of skin cancer3.
UVB rays affect the upper layers of our skin and are responsible for causing sunburn. They also play a role in aging and development of skin cancer. UVB rays will differ in intensity depending on the time of year, time of day and location - which means they are stronger during summer months in the middle of the day4. That being said, they are dangerous all year round.
How do I know if my sun cream is protecting me?
According to recent studies there is a lot of confusion surrounding sun cream and how it can protect us from UV rays. The study revealed that many Britons are unaware that sun cream has two protection ratings - one for UVB rays and one for UVA5.
For many, SPF is the main rating considered when buying sun cream. SPF stands for Sun Protection Factor, and the number given relates to the length of time you can stay in the sun before you begin to burn. Thus SPF 15 sun cream would allow you to stay in the sun without burning 15x longer then you could without sun cream on. Furthermore the SPF rating will also relate to the amount of UVB rays the sun cream filters out. SPF 15 will filter out 93% of UVB rays, while SPF 30 can filter out 97%6.
In addition to SPF ratings, sun creams should also come with a star rating that shows you how strong their UVA protection is. UVA protection is measured differently than UVB however, and the stars indicate how high the UVA protection is as a percentage of the SPF rating. This means that an SPF 20 sun cream with 4 stars may actually have less protection than that of an SPF 30 with three stars7.
If you don't see a star rating, you may see the letters UVA in a circle. This means the sun cream adheres to EU recommendations which state that sun creams' UVA protection should be at least a third of the SPF rating8.
When should I wear sun cream?
Even when the sun isn't as hot, and the days aren't as long, it's important to remember that UV rays reach us all year, even in the winter! So while you're probably more likely to apply sun cream in the summer months, you should make an effort to protect yourself year round. The good news is that in the cooler months most of our bodies are protected by clothing, but you should make an effort to apply sun cream to exposed skin, such as your face.
How much sun cream should I apply?
Even if you've bought and applied an SPF 30 sun cream, you may not be getting as high protection as you think you are. This is because you may be applying your sun cream too thinly. Studies have shown that most people do not apply enough sun cream and thus are receiving a far lower SPF than they think they are9. To make sure you're covered you should generally apply enough cream to fill a shot glass - a bit more than two tablespoons.
However this amount may need to go up or down depending on your body size10.
You should also make sure to use SPF lip protection, as our lips are easily susceptible to sunburn and can also develop skin cancers.
How often should I reapply sun cream?
Sun cream should be reapplied at least once every 2 hours. Even if you're using a cream that says it lasts longer, you should reapply as a number of factors could lead to it wearing off such as sweating, swimming, and abrasion - like towel drying or changing clothes.
If you go swimming, you should reapply immediately after (once your skin is dry) instead of waiting the two hours. While some sun creams will claim to be 'water resistant', sun cream isn't waterproof. The Food and Drug Administration in the USA has even gone as far as to ban the use of terms like 'Waterproof' on sun cream labelling11.
Can I use makeup instead of sun cream?
These days many cosmetics such as moisturizer and foundation come with SPF protection built into them. Some of us may assume that this alone is enough to keep our faces protected in the sun, but that may be a mistake.
When we apply sun cream, we usually use far more than we'd use of, say, foundation. Unless you heavily cover your face in makeup the chances are you won't be getting nearly as much SPF as stated on the bottle. You also need to keep in mind that, like sun cream, you need to reapply often to maintain protection12. So while the SPF that makeup provides is better than nothing, you'd likely be better off using a proper sun cream. Especially if you intend to be outside for long periods of time.
- http://www.skincancer.org/skin-cancer-information/ask-the-experts/how-much-sun cream-should-i-be-using-on-my-face-and-body