SPF Rates Protection from UVB Rays
The sun emits ultraviolet rays that are categorized as UVA or UVB.
UVA rays are responsible for a tan but they also penetrate the skin deeply to cause damage that can lead to premature aging and skin cancer.
UVB rays are the main cause of sunburn and are also linked to skin cancer.
The sun protection factor, or SPF, rating that you may be familiar with protects you from UVB rays and burning, but not from the damaging UVA rays.
“It’s important for people to read and understand what’s on the sunscreen label because you might not have the protection you think you do,” said Ashley Johnson, LA, a medical aesthetician at Samaritan Plastics, Reconstructive & Hand Surgery.
The SPF number correlates to the percentage of UVB rays that are blocked. The Skin Cancer Foundation reports that sunscreen with an SPF of 15 blocks 93 percent of UVB rays, SPF 30 blocks 97 percent and SPF 50 blocks 98 percent of UVB rays. It might seem like a small increase, but for people who burn easily the extra protection afforded by higher SPF is valuable.
“In theory, the SPF number is a multiplication factor that also tells you how long you can be in the sun before you will burn, so someone who might normally burn after 15 minutes could use SPF 15 and be in the sun for 225 minutes,” said Johnson. “In reality, that time is much less because the intensity of the sun’s rays change during the day. If you have fairer skin, you probably need a higher SPF, and we always recommend people reapply sunscreen every two hours no matter what SPF they use.”
The American Academy of Dermatology recommends everyone use a broad spectrum SPF of 30 or higher and to avoid the sun between 10 a.m. and 2 p.m., when the sun’s rays are the strongest.
PA Rates Protection from UVA Rays
It’s not a given that sunscreen will block UVA rays that are responsible for skin damage and cancer, even if it has a high SPF number. Look for “broad spectrum” on the label, which indicates there is also UVA protection. As the SPF number gets higher the UVA protection also increases on broad spectrum sunscreen; however, the amount of filtering power that’s provided is not specified like it is with UVB.
The new “protection of UVA” (PA) grading system evaluates how much skin will tan while using a product, meaning consumers now have a way to compare how much UVA protection they are getting.
“The system is good to use in conjunction with an SPF rating when you are evaluating sunscreens because it can give you an idea of what the protection is from UVA rays,” said Johnson. “However, because each person’s skin can darken and tan at a different rate, the PA grade is not an absolute measure of UVA blocking power.” Despite its shortcomings, the PA rating is a good place to start when comparing UVA protection. In general, more pluses translates to more protection:
• PA+, some UVA protection
• PA++, moderate UVA protection
• PA+++, high UVA protection
• PA++++, extremely high UVA protection
“Ideally, you want the PA rating to be as high as possible to give you the most protection from the damage that leads to skin cancer or premature aging like spots, leathery skin and wrinkles,” said Johnson.
Johnson recommends SkinMedica sunscreens, which are rated PA++++. The brand carries two formulas for different skin care needs.
If your sunscreen doesn’t include a PA rating on it, look for active ingredients like avobenzone, titanium dioxide or zinc oxide. These are all approved by the U.S. Food & Drug Administration to block UVA rays.
“A good quality, broad spectrum sunscreen is one of the best ways to protect your skin,” said Johnson.
Request a complimentary skin consultation at Samaritan Plastics, Reconstructive & Hand Surgery, and find the right sunscreen for your skin type.