What does SPF stand for?

• A. Sun protectant factor
• B. Sun Protection Factor
• C. Solar Protection Factor
• D. Sun Protectant Finish

Answer: (A)

SPF stands for Sun Protection Factor. This is the label term used to describe how much longer you can stay in the sun without burning when using sunscreen, compared with unprotected skin. It’s a ratio: MED (the minimum amount of sun exposure that causes a sunburn) with sunscreen divided by MED without sunscreen. So, an SPF 30 product suggests you could stay in the sun about 30 times longer before burning, under ideal conditions, than you could without protection.

In practice, higher SPF means more protection from UVB rays, which are the primary cause of sunburn. However, SPF mainly reflects UVB protection; it does not measure UVA protection, so you want a broad-spectrum product to cover both UVA and UVB. Also, real-world factors like sweating, water exposure, and reapplication every two hours (or after swimming) affect actual protection.