Why SPF Matters And What You Need To Know
31 May 2020
If you read any of our articles over spring and summer, you’ll know we harp on a lot about the importance of SPF. But let’s face it, while most of us know that we should be using an SPF product, we don’t really know the ins and outs of why.
Well, it’s time for all that to change. By understanding how SPF is determined and what it actually means, we can all make sure we’re making the right decisions to protect our skin in both the short and long-term. Let’s unravel some of the mystery around SPF products.
If you’re interested in sun protection, you may also want to read our article on Zinc Oxide and Titanium Dioxide.
What is SPF?
SPF is an acronym for Sun Protection Factor – it’s the way that your protection from ultraviolet rays is measured. It’s important to note here that the SPF only takes into account UVB rays, but we’ll discuss why this matters in more detail a bit later.
The SPF rating is a universal measurement that all sunscreen products are ranked against to give more clarity to consumers as to how much UVB protection they can expect from their purchase.
Broadly speaking, an SPF 15 sunscreen allows you to have 15x longer sun exposure without the risk of burning. So, if under normal conditions the time taken to burn is 10 minutes, an SPF 15 would extend this to 2.5 hours.
Of course, this should never be taken as a certainty, as many elements can reduce this time. Your skin colour, genetic makeup, global location and weather conditions can all impact how quickly you will burn, so SPF should only serve as a guideline.
How Is SPF Measured?
The SPF rating of a sunscreen product helps us to identify how much more protected our skin is than if we were wearing no sunscreen at all. If used exactly as directed, an SPF 15 blocks 93% of UVB rays, an SPF 30 blocks 97% and an SPF 50 blocks 98%. On the face of it, this might seem like a negligible difference, but let’s look at those figures a little closer.
If the sun puts out 100 photons (particle of radiation), this is how the various SPFs would stack up:
No SPF, 0% protection – 100 photos reach the skin
SPF 15, 93% protection – 7 photons reach the skin
SPF 30, 97% protection – 3 photons reach the skin
SPF 50, 98% protection – 2 photons reach the skin
So, using an SPF 30 product is twice as effective as an SPF 15, letting half as many photons reach the skin, while an SPF 50 is three times more effective as an SPF 15, letting only a third reach the skin. Considering that every particle of radiation can cause immense damage to your skin, this really matters.
Unfortunately, there is an unexpected risk to using a high SPF compared to a lower SPF. For some people, using a high SPF sunscreen produces a false sense of security, leading them to spend longer in the sun, not reapplying regularly and not seeking shade. This can result in more sun damage than if they had used a lower SPF and taken more care.
So, while a high SPF does offer better protection, your own actions can have just as significant an impact on your skin’s protection.
UVA vs UVB Rays
Another thing to be aware of when thinking about sun protection is that the SPF rating of a product only refers to its protection against UVB rays, not UVA. The sun actually creates three different types of radioactive ultraviolet ray, UVA, UVB and UVC.
UVB rays are what sunscreen protects against, and what the SPF label relates to. While most UVB is filtered by the atmosphere, what does reach the Earth damages the superficial, outermost layer of our skin. UVB rays cause sunburn and significantly increase the risk of skin cancers.
UVA rays account for roughly 95% of the UV rays that reach the Earth. While they were once considered harmless, we now know that UVA penetrates deeper into the skin than UVB rays, causing ageing of the skin and wrinkling. UVA rays are also what creates a suntan, which is actually our skin trying (poorly) to defend itself against damage. Recent studies have also indicated that UVA rays may create further risk of skin cancers.
While UVC rays are the most harmful form of radiation emitted by the sun, it is filtered through the atmosphere and doesn’t reach the Earth’s surface.
As you can see from the information above, it isn’t only UVB we need to worry about, UVA rays are just as much cause for concern. For this reason, it’s important to look for sunscreens which are labelled as “broad spectrum” or “full-spectrum”. These products include ingredients designed to deflect UVA rays as well as UVB.
How Often Should You Reapply?
The Skin Cancer Foundation recommends opting for broad-spectrum, water-resistant sunscreens with an SPF of 30+ for any extended time spent outdoors. Irrespective on the SPF, the correct application is key. The average adult should apply about a shot glass worth, or two tablespoons, 30 minutes before going outside. The sunscreen should then be reapplied every two hours, or more frequently if sweating or swimming.
What Types Of SPF Products Are There?
Any area of your body that is exposed to sunlight would ideally be protected from UV rays. While this can be achieved by wearing long clothing, a hat and seeking shade, most of us are likely to, at some point, want to enjoy full sunshine without additional layers – that’s where SPF protection comes in.
There are five main categories of SPF: Hair, Lips, Face, Body, Child.
Believe it or not, the UV rays and heat from the sun affects our hair as well as our skin. Though it doesn’t cause the same health concerns, UV damage to hair can leave it dry, frizzy and untameable.
Shop SPF Hair Protection
The skin on our lips is only 3 to 5 layers thick, compared to around 16 layers on the rest of the body. This makes our lips much more susceptible to burning. Using a lip balm or lipstick with SPF protection is an absolute must for this reason.
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Our face is exposed to more sunshine than most other areas of our body, but it’s also the area of the body that is most susceptible to sensitivity, dryness, acne or other skin complaints. For this reason, complexion specific sunscreens are a great choice.
Shop SPF Face Sunscreens
Providing overall coverage on all areas that are exposed to the sun, body sunscreens are designed with a range of activities in mind. With SPFs ranging from 15 to 50+ and in a range of textures, there’s something for everybody.
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SPF sunscreen for children is designed using gentler formulations that prioritise sensitivity. For this reason, it is often also recommended for adults with particularly sensitive skin, such as those suffering from eczema or dermatitis.
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Are you all set for the warmer weather? You can browse our full Sun & Tan range here.