How to Use Sunscreen

Choosing the right sun protection and applying it properly are the most important steps you can take to protect your skin from the sun’s harmful rays. It sounds simple, but these steps are often misunderstood. Here are the basics: 

• Use a sunscreen with an SPF of 30 or higher.
• About two tablespoons (six teaspoons) is enough sunscreen for the average adult body, with about one teaspoon allotted for just your face.
• Apply sunscreen about 15 minutes before going out in the sun and reapply it every couple of hours.

 In 2013, new labels began appearing on sunscreen bottles, per orders from the FDA. Some of the changes affect the terms permitted on labels. “Sunblock” must now be called sunscreen, and the descriptions “sweat proof” and “waterproof” aren’t allowed. Now, a sunscreen can be called “water resistant” only for either 40 or 80 minutes—and only if it passes an FDA test. 

But the more important terms focus on what sunscreen can prevent. For a label to claim the sunscreen can prevent sunburn, the product must pass the sun protection factor (SPF) test. This test shows how long a sunscreen protects you from ultraviolet B (UVB) rays that cause sunburn. SPF levels range from 2 to more than 70. The higher the number, the longer the protection lasts. Say, for example, your skin turns red after 10 minutes in the sun. Sunscreen with an SPF of 15 would prevent your skin from turning red for 150 minutes under the same conditions.

You might think that an SPF of 30 would work twice as well as an SPF of 15. But that’s not necessarily the case. While SPF 15 filters out approximately 93% of all incoming UVB rays, SPF 30 filters out 97%, and SPF 50 boosts that to 98%. The American Academy of Dermatology recommends using a sunscreen with an SPF of at least 30. According to the FDA, you don’t need a sunscreen with an SPF higher than 50, because there’s no evidence that sunscreens with an SPF above 50 offer any additional protection.

For a product to claim it can prevent skin cancer, it must pass the broad-spectrum test. This shows whether a sunscreen can protect your skin from ultraviolet A (UVA) radiation, which contributes to skin cancer and early skin aging, as well as UVB rays.