What is SPF
SPF stands for Sun Protection Factor and protects the skin from UVB radiation. It doesn’t protect against UVA.
How do SPF numbers work?
The numbers which range from 2 to +50 tell you how long your skin will take to redded with the product compared to how quickly it will redden with no protection. So if you have appropriately applied an SPF 15, it would take your skin 15 times longer to go red as compared to having no sunscreen on.
So if your skin normally reddens after 10 mins in the sun, applying an SPF 15 sunscreen would allow you to stay in the sun for 150 mins.The higher the number the longer the protection. However, SPF is actually a measure of the degree of protection it gives you from UVB rays and should not be used to determine the length of sun exposure.
How do I protect against UVA?
UVA protection is rated with stars from 1-5. This rating system is called the UVA Seal, the recommended minimum protection is 4 stars.
Not all countries require the same labelling or use the same system, especially for UVA countries like Japan that use a PA system. It’s always best to bring your own trusted sunscreen from home where possible.
All sunscreens should be applied every 2 hours at the latest and more often if you are sweating or swimming.
Overall for adults, an amount that is equivalent to a full shot glass is adequate.
- Face and neck: Half a teaspoon
- Arms: One teaspoon
- Legs: Two teaspoons
- Front and Back of torso: Two teaspoons
Do I need to wear sunscreen if I’m using SPF moisturisers?
If you are going to be exposed to lots of light with a UV index higher than 3 you should be using SPF 30 or above. SPF moisturisers are otherwise great for less sunny days.