UV stands for ultraviolet, and both UVA and UVB are ultraviolet radiation (rays) from the sun that penetrate the ozone layer. Both UVA and UVB rays are harmful to unprotected skin when exposed for prolonged periods with no sun cream.
UVB is the main cause of burning, and mainly affects the outer layer or epidermis of the skin. However, UVA can penetrate deeper into the skin and affect cells within the dermis and subcutaneous layers of the skin. Both UVA and UVB can cause cells to mutate and lead to cancer.
SPF stands for sun protection factor and is the indicator of the protection a sunscreen offers against the ultraviolet (UVB) rays from the sun. Without any protection, skin can burn and prolonged exposure to the sun’s rays can cause premature ageing and, in some cases, skin cancer.
A sun cream with an SPF of 15 means it will take approximately 15 times longer for the skin to burn than if you have no sun cream on; or with an SPF of 30 means it will take 30 times longer and so on.
The SPF offers a screen from the UVB rays from the sun: SPF 15 will screen approximately 93% of the UVB rays, SPF 30 screens 97% and SPF50 screens 98%. Remember the SPF is just an indicator, and unless you apply ample amounts of sun cream, you may not reach these protection levels.
It is vital that the sun cream you choose also offers protection against UVA radiation too.