When it comes to sun cream, the higher the factor the higher the protection, right? But what happens when you apply less than the recommended amount?
Some people believe that when applying a higher factor, they can use a smaller amount of sun cream and still be adequately protected from the sun’s harmful UV rays, however this is not necessarily the case.
According to the British Association of Dermatologists, most people apply less than half of the amount required to provide the level of protection indicated on the packaging.
A 2007 study published in the British Journal of Dermatology, says that applying half the recommended amount of sun cream would only give you the square root of the stated SPF. This means that the higher the SPF, the more rapidly the protection falls off with under-application.
This shows that it is very important to reapply liberally and frequently.
How much does under-applying affect SPF?
Applying half the amount of:
- SPF15 will give the protection of SPF3.9
- SPF30 will give the protection of SPF5.5
- SPF50 will give the protection of SPF7.1
How much sun cream should I apply?
Sun creams are generally tested at an application level of 2.0mg per cm² of skin. This equates to about 30g to cover the whole of an adult body. If less than this amount is applied, you will not be getting the protection level stated on the bottle.
An easy way to remember how much sun cream to apply is to use an amount the size of a shot glass for the entire body, every time you re-apply.
If you are only applying sun lotion to certain areas of the body, e.g. exposed arms, use an amount the size of a 50p (around 3g) for each arm, or for exposed legs use twice this amount. Your entire face and neck will also need a 50p-sized amount of sun lotion.
It is notoriously difficult to tell how much product you have applied when using a spray-on sun lotion, particularly one packaged in an aerosol can.
Aerosol sunscreens that deliver a fine mist over the skin may seem like a convenient option, but it is very easy to under-apply with this type of product.
Due to the packaging design, there is no real way to tell how much product you have applied, or how much is left in the bottle.
For people with sensitive skin and those prone to prickly heat, spray-on sunscreens are usually best avoided, as they often contain harsh, irritating chemicals such as alcohol denat, which is used to give the product a light skin-feel.
For skin-friendly organic sun creams, try Green People’s award-winning sun care range for adults and children in medium and high factors.
Providing broad-spectrum UVA and UVB protection without harsh chemicals, Green People sun creams are suitable for ultra-sensitive skin and those prone to eczema and prickly heat.