What does SPF really mean?

What does SPF really mean?

SPF stands for Sun Protection Factor and the number beside it indicates how well the sunscreen protects skin from sunburn. In other words, it’s an indicator of how much longer it takes untanned skin to begin to redden with sunscreen compared to untanned skin without sunscreen. To determine the SPF number, laboratory tests are carried out on human volunteers using an untanned patch of skin. A simple formula is then applied dividing the number of seconds it takes the patch of skin to slightly redden with sunscreen, divided by the number of seconds it takes the patch to redden when no sunscreen has been applied.

1. 300 seconds to redden with sunscreen/10 seconds to redden with no sunscreen = SPF 30

It is also important to understand that the SPF number is only an indicator of how well the sunscreen blocks UVB radiation not the deeper penetrating UVA radiation. If you want protection against both, you’ll need to ensure that your sunscreen is labelled as Broad Spectrum as this means additional laboratory tests have been carried out.

You’re using sunscreen but you’re still getting burnt. Why?

The short answer is no sunscreen is able to block out 100% of UV radiation no matter how high the SPF and therefore no sunscreen has the ability to completely block sunburn and associated skin damage. Sunscreen is merely one part of an effective sun protection regime and in order for it to work most effectively it must be applied liberally and regularly. SPF tests are determined on volunteers on which a liberal amount of sunscreen has been applied. This means in order to achieve the protection on the label you need to apply sunscreen thickly and regularly (every 1-2 hours), and lots of people don’t.

What’s the difference between SPF 30 and SPF 50?

Most people assume that bigger SPF means much better protection, but the reality is there’s very little difference between an SPF 30 and an SPF 50. SPF 50 sunscreens filter 98% of UVB radiation compared to 96.7% for SPF 30 sunscreens and the reality is that an SPF 30 sunscreen applied properly will give better protection than an SPF 50 sunscreen applied too thinly or too infrequently.

{SIMPLE as that}