You may be confused when shopping for an SPF, seeing numbers such as 15, 30, 50, 70. SPF Sun Protection factor is a measurement of ultraviolet B (UVB) Protection.
- SPF 15 blocks 93% of UVB
- SPF 30 blocks 97% of UVB
- SPF 50 blocks 98% of UVB
therefore, a higher SPF does not significantly increase your protection; as long as you are using an SPF of at least 30 daily.
Ensure to choose a sunscreen which says Broad Spetrum; it covers both UVB (the burning rays) and UVA (the aging rays).
With prolonged sun exposure, it is important to re-apply every 2 hours.