SPF Sun Protection Factor numbers explain sun lotion active ingredients that begin at two and go up to 70.

To work out how long you can sit in the sun wearing a particular SPF Sun Protection Factor you apply the following equation:

Minutes it takes to burn wearing no sun protection at all multiplied by the SPF Sun Protection Factor.  This equals the maximum time you can stay in the sun.

If you would normally burn after 10 minutes in the sun and are using a SPF of 10, this means that theoretically you could stay in the sun for 100 minutes and not burn.  A higher SPF number equals a longer safe sun-exposure time

The number is also relevant to the absorption level of UVB, but this can lead to confusion.  This is because it is not exponential.  An SPF marked 15 will absorb 93.3% of the UVB rays, whereas an SPF of 30 will absorb 96.7%. Although the SPF is double in this particular example, the actual rate of absorption has increased only by 3.4%.

Sun Lotion prevents the strong ultraviolet component in sunlight from causing damage our skin.  UV light falls into two categories: UVA is the cause of sunburn, and UVB causes more long term damage, such as premature ageing and can penetrate clouds and glass.

While it is important to be aware of the science behind SPFs, you should also use basic common sense when it comes to protecting yourself in the sun.  Stay out of the sun between midday and 3pm and protect your eyes with sunglasses, use the correct SPF lotion and apply plenty of it, reapply frequently.

When applying your sun lotion, make sure you have covered absolutely all exposed areas, including the back, a place that is notoriously hard to apply sun lotion to.  Use a BackBliss back lotion applicator and you’ll be surprised at just how quick and easy it is to cover your back.