Everything you need to know about SPF

SPF stands for ‘Sun Protection Factor’ and measures the amount of protection you get from the sun’s UV (ultraviolet) rays. The higher the SPF, the better the protection.  SPF typically ranges from 2 to 50, which tells you how long it will take for your skin to burn compared to if you weren’t using any protection. So, if it typically takes you 10 minutes to burn without protection, an SPF30 will protect you for 30 times longer, which is 5 hours.  

UVA and UVB are both ultraviolet rays. UVA is a longwave which penetrates the skin’s thickest layer whereas UVB is a short wave which burns the surface layer of skin. UVA is responsible for tanning, but it’s also the main culprit for triggering the visible signs of aging – wrinkles and brown spots. UVB rays are the ones that do serious damage – they’re responsible for sunburn as well as tanning and premature ageing, and they also cause the long-term damage that can lead to skin cancer.

Sunburn isn’t just annoying, it’s your skin’s way of sending you a warning sign that your cells are damaged. UVB rays damage the DNA in your cells – if this builds up. It causes cells to mutate, which can lead to cancer. Sun exposure is the biggest trigger of aging skin – just as an apple goes soft and wrinkly when it’s left out in the sun, so will your skin (over time it’s kinda inevitable, but you can keep them at bay with daily SPF use). 

Chemical sunscreens absorb radiation and convert it to heat to prevent UV damage from occurring (so sun is basically absorbed and then released from the skin), whereas physical sunscreens act as an actual barrier to reflect UV radiation and prevent the sun’s rays from even penetrating the skin. For this reason, physical SPF can sometimes feel quite thick and chalky, whereas chemical SPFs will be much lighter and smoother on the skin. To work out whether a sunscreen is physical or chemical, check the ingredients list. Essentially, if it contains either zinc oxide or titanium dioxide then it’s physical. And if it doesn’t, then it’s chemical. If your skin is sensitive or breakout-prone, then go for physical (the ingredients are less likely to cause irritation).  

It’s super important to wear sunscreen when it’s sunny because that’s when you’re prone to burning. But really, in order to prevent long-term damage, you should add an SPF into your everyday routine. UV rays can penetrate through clouds, windows, and even clothing, so if it’s not prevented, damage builds up slowly over time. Because sunscreens can easily wear off (due to water exposure and contact with clothing), if you’re in strong, direct sunlight you should reapply every 2-4 hours (and more frequently with exercise, swimming, or towelling off). 


Expiry dates – most sunscreens will last for a year after opening. Once they’ve gone-off, the formulas can deteriorate and end up useless. 

Don’t forget all areas – the back of your neck, tops of your ears, backs of your hands, your lips, and your scalp are all vulnerable to damage, but often forgotten.  

Apply at least 30 mins before sun exposure – this gives the ingredients enough time to absorb into skin. 

You don’t need higher than SPF50 – 50 gives you 98% protection from the sun’s rays, so it’s very hard to get any higher than that!


Culled from BeautyBay