What does SPF stand for in relation to sunscreen?

SPF stands for Sun Protection Factor, which is a measure that indicates the level of protection a sunscreen provides against ultraviolet (UV) radiation, specifically UVB rays that cause sunburn and contribute to skin cancer. The SPF value represents the amount of time a person can be in the sun without getting burned compared to the time without sunscreen. For example, if someone typically burns after 10 minutes in the sun, using a sunscreen with an SPF of 30 theoretically allows them to stay in the sun 30 times longer—around 300 minutes—without burning.

Understanding SPF is crucial for effective sun safety practices, as it helps individuals choose appropriate sunscreen products based on their skin type and expected sun exposure. The other options don't accurately represent the common terminology used in sunscreen labeling and would not provide the correct context for measuring sun protection.