Most of us, at some point, has spent considerable time scratching their heads on the sunscreen aisle. The common question being, "which product will provide the best sun protection."
We then reach for a bottle of SPF 100, assuming that it is the better option. On the contrary, however, SPF ratings are not like scoring test points, higher does not necessarily mean better.
SPF 101
You may or may not be aware that SPF or Sun Protective Factor, operates under a unique set of rules. Basically, SPF does not follow a linear scale, meaning its numerical representation is not correlational. In short, higher SPF numbers do not automatically assure more UV protection.
For example, you should not expect SPF 100 to be twice as strong as SPF 50. In fact, going for a product with anything more than SPF 30 provides little additional skin protection. According to studies on the effectiveness of SPF, SPF 15 blocks about 93% of sun rays, while SPF 25 blocks about 96% of sun rays. Similarly, SPF 30 blocks 97% of sun rays, while SPF 50 blocks close to 98% of ultraviolet sun rays.
To complicate it further, the non-linear attributes of SPF go both ways. For example, if you apply half of the recommended amount of sunscreen, you do not receive half of its protection. Instead, you will get its square root, proposing that using half of SPF 30 does not give you SPF 15, but 6. This math will definitely give you a head spin, but the following guide will inform you how to maximize your sunscreen products' benefits by assessing SPF levels.
What You Need to Know About SPF
SPF functions like a math equation. Taking the time it takes your skin to burn without applying any sunscreen multiplied by the SPF determines the period of time you can stay in the sun with sunscreen.
This equation is not practical because of several reasons. First, no one goes out in the sun to record the time it takes for their skin to burn without sunscreen. Additionally, results might suggest that some sunscreen products will protect you for more than two hours. This undermines the dermatologist recommendation to apply sunscreen at least every two-hours.
So, What is the Solution?
Professionals suggest that you should apply SPF 25 for day to day protection, rain or shine. SPF 25 protects the skin from about 96% of UV rays, providing reliable protection. SPF 30+ is suggested when engaging in prolonged outdoor activities. Dermatologists also recommend sunscreens labeled broad-spectrum because they offer the ultimate UVA and UVB protection. Moreover, you can implement additional solutions like shading or wearing hats and long sleeves.
In conclusion, don't stress out worrying about which SPF to choose. Focus on appropriately applying your sunscreen and reapplying the recommended every two hours!
