The science behind sun protection

Summer is here. And that means being extra vigilant in protecting your skin from the sun’s harmful UV rays. But when it comes to being sunsmart, there are a few rumours out there. Here, we debunk the myths around SPF (Sun Protection Factor), so you can feel better prepared this summer.

1. True or false? You only need to apply sunscreen every 4 hours

FALSE. According to Cancer Council Australia, sunscreen should be reapplied every 2 hours -- no matter what level of SPF you’re using. Additionally, you should reapply after swimming, exercising and drying yourself with a towel -- basically any activities that could remove the sunscreen.

It’s important to apply liberally to achieve the level of SPF claimed on the label. For proper protection, use at least a teaspoon for each limb, as well as the front and back of the body, and half a teaspoon for the face, neck and ears.

2. True or false? A tan protects your skin from getting burnt

FALSE. There’s no such thing as a ‘safe tan’. When you have a tan, the UV damage has already been done, and while this may provide you with an SPF of about 3, it’s too insignificant to prevent any further damage, and therefore adequate sun protection is required.

3. True or false? It's important to get some 'sunscreen-free' time to expose yourself to vitamin D

TRUE. The sun’s UV radiation is your body’s best, most natural activator of vitamin D. However it’s important to note that the amount of UV exposure your body needs depends on a few important factors, including time of year, UV levels, skin type, and whether you’re at risk of a vitamin D deficiency.

For example, from May to August (in some southern parts of Australia, when the UV Index falls below 3), it can be safe to spend time outdoors with some skin uncovered. However, during warmer months, when the sun’s UV rays are much stronger, it’s important to practice sensible sun protection to avoid the risk of skin cancer. To play it safe, track your vitamin D levels with this SunSmart tool, or download the SunSmart app for iOS or Android to see the UV levels throughout the day.

4. True or false? There are health risks associated with SPF

FALSE. Over the years, concerns have been raised over the potential risks of sunscreen chemicals -- zinc oxide, titanium dioxide nanoparticles and microfine particles -- being absorbed into the bloodstream. However, Aussies can rest assured -- according to the Therapeutic Goods Administration (TGA), nanoparticles do not penetrate the underlying layers of skin, suggesting bloodstream absorption is unlikely. Additionally, a study in 2014 found that even if nanoparticles were to be absorbed into the bloodstream, the body’s immune system can effectively break them down.

While the TGA advises neither zinc oxide or titanium dioxide nanoparticles are harmful ingredients in sunscreen, if you’re concerned about chemical absorption, simply opt for a sunscreen that does not contain nanoparticles.

5. True or false? SPF is one of the world's best anti-agers

TRUE. UV radiation is responsible for up to 80% of fine lines and wrinkles. This process is called photoaging -- or premature aging -- and describes a loss of the skin’s elasticity, a dry and wrinkled appearance, and patchy pigmentation. According to a study which looked at whether daily sunscreen application could decrease skin aging in men and women under 55, regular sunscreen use was associated with no detectable increase in skin age after 4.5 years -- just another reason to slip, slop, slap.

For more information on sun safety, visit Cancer Council Australia.