Deciphering the Sunscreen Numbers

dermatologist in orange countySince the first “sun protection factor” -€ SPF -€ numbers started appearing on sunscreen labels, an entire generation of children are now in their 30s. For many people, however, what those numbers mean remains a mystery. As a dermatologist in sun-splashed Orange County, I consistently hear questions about how to choose sunscreen and whether an SPF 50 product is really necessary.

First, it’s important to know what the SPF numbers mean and what type of sun rays are being screened when you spray or slather on sunscreen. The first SPF numbers in the late 1970s were 4, 8, 12, and 15. An SPF of 15 means someone who applies the sunscreen can stay in the sun 15 times longer before getting sunburned. So, SPF 30 offers twice the protection, right? Well, no.

That’s because the SPF number refers to the sunscreen’s ability to screen ultraviolet B (UVB) radiation. An SPF of 15 screens 93 percent of the sun’s UVB rays, so there is only an incremental increase for higher SPF numbers. A sunscreen with SPF 50 screens about 99 percent of the UVB rays.

Just as important as the SPF number is finding a product that offers “broad-spectrum” protection, which means it screens both UVB and UVA rays. UVA rays penetrate deeper into the skin and pose a greater risk of non-melanoma skin cancer. In fact, a recent study concluded that triple protection factor broad-spectrum sunscreen (TPF50) is more effective than traditional sunscreens.

The bottom line is sun protection should be part of your daily routine, with a minimum SPF of 30. A number of high-quality products that don’t leave your skin oily exist today, such as moisturizers that include sunscreen. My Beauty Bar MDSM, OC Dermatology’s exclusive center for premium skincare products, offers several options, and our skincare team can help you find one that’s easy to incorporate into your beauty regimen.

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