There are two reasons why I chose this topic for my article; first because it’s the sunbathing season; and on the other hand, because it’s the debut of our long-awaited PANDHY’S™ sunscreen products.
Every person’s skin has a certain tolerance for sun, and SPF (Sun Protection Factor) multiplies that tolerance.
If you can spend 15 minutes in the sun without getting burned, applying the appropriate amount of an SPF 15 product would allow you to spend 15 times 15 minutes in the sun.
Minutes to burn without sunscreen x SPF number = maximum sun exposure time
But before you grab your calculator and head for the beach, you should know that this equation is not always accurate.
First of all, people usually use far less sunscreen than the amount used in the testing phase, in laboratory conditions. In the real world, the average sun worshipper uses half the amount of sunscreen used in the laboratory, which can result in a sunburn in half the time.
Furthermore, despite waterproof or sweatproof labels, all sunscreens decrease in effectiveness when exposed to water or sweat, so regular reapplication is very important to secure ongoing protection.
We can define SPF in another way, describing what percentage of UV rays does the sunscreen absorb based on the SPF. For example, that SPF 15 sunscreen would allow 1/15 of the UV rays through, which means that’s about 6.7% of the rays get through the sunscreen.
Here’s where it’s getting interesting. Using this formula, an SPF of 45 allows your skin to absorb 2.2% of the UV rays. As you can see, SPF increased threefold, but the protection of the skin only increased by 4.5%.
Some use that data to claim that SPF 15 is really all you need since higher SPFs don’t add that much protection at all, so higher factor number is only a marketing gimmick.
Because of the confusion about UVB absorption, in 2011 the FDA proposed a cap on SPF numbers. They suggested using “30 plus” label on each product if the SPF was higher than 30. Besides, they were considering banning factor numbers above 50, but finally, it did not happen, and we can still find these products on the shelves.
Thirty was the decided cap because above that, the percentage of UVB absorbed and overall protection of the skin increases only slightly, but people may misinterpret these higher SPF numbers as a much higher level of protection or even a guarantee of all-day protection.
Here is a comparative chart to illustrate this:
|SPF||% UV absorbed|
Often studies show that those who use a higher SPF are more likely to get melanoma (skin cancer), possibly because they’re tricked into thinking they’re safe from the sun and stay out longer.
Tan wisely and enjoy the good weather!