SPF stands for Sun Protection Factor, and it is a measure of a sunscreen's ability to protect the skin from harmful ultraviolet (UV) radiation emitted by the sun. SPF primarily indicates the level of protection a sunscreen provides against UVB rays, which are responsible for causing sunburn and increasing the risk of skin cancer.
The SPF number on a sunscreen product represents the level of protection it offers against UVB rays. The higher the SPF number, the greater the protection. For example:
SPF 15: Provides moderate protection against UVB rays. It allows you to stay in the sun without burning for approximately 15 times longer than without sunscreen.
SPF 30: Offers higher protection against UVB rays compared to SPF 15. It allows you to stay in the sun without burning for approximately 30 times longer than without sunscreen.
SPF 50+: Provides the highest level of protection against UVB rays. SPF 50+ sunscreens offer significantly more protection than lower SPF sunscreens.
It's important to note that no sunscreen can block 100% of UVB rays, regardless of its SPF. Additionally, SPF only measures protection against UVB rays, so it's crucial to choose a broad-spectrum sunscreen that also protects against UVA rays, which contribute to skin aging and can cause skin cancer.
When using sunscreen, it's essential to apply it generously to all exposed skin and to reapply regularly, especially after swimming, sweating, or towel-drying, as well as every two hours when spending prolonged periods in the sun.