What does the number following an SPF rating indicate?

The number following an SPF rating specifically indicates the level of protection a sunscreen offers against UVB rays, which are primarily responsible for causing sunburn and contributing to skin cancer. The SPF number essentially reflects the number of times longer a person can theoretically stay in the sun without getting burned compared to not wearing any sunscreen at all. For example, if a person would typically start to burn after 10 minutes of sun exposure, using a sunscreen with SPF 30 would theoretically allow them to stay in the sun for 300 minutes (30 times longer) before experiencing the same level of UV-induced redness.

While it’s important to note that this theoretical duration can be impacted by factors such as skin type, the intensity of the UV rays, and the amount of sunscreen applied, the SPF rating provides a standardized measure of sun protection effectiveness. This understanding highlights the significance of the SPF number in aiding consumers in choosing appropriate sun protection based on their needs and exposure conditions.