With summer being hotter than ever, sun protection for your skin could not be more important. But the world of sun protection can be hard to understand when there are industry terms like SPF, UPF, UVB, and UVA. What do they actually mean? Let’s take a look at what SPF and UPF are and how they differ.
SPF (sun protection factor) and UPF (ultraviolet protection factor) refer to protection levels against ultraviolet (UV) radiation in sunscreen and in clothing, respectively. Both are rating scales that refer to how long you can stay in the sun with them before getting burned. SPF only refers to protection against UVB rays, while UPF measures the protection level against both UVA and UVB rays.
According to the American Cancer Society, the SPF number you see on sunscreen bottles is the level of protection the sunscreen is providing against UVB rays. UVA ray protection does not have a formal rating system in the United States yet, unfortunately, though in the past a star rating system was used.
UVA and UVB Rays
But what is the difference between UVA and UVB rays? They are both potentially damaging and have interesting differences in main effect, though they are, of course, part of the same section of the light spectrum– the ultraviolet end, past the violet end of the visible light spectrum.
According to the Skin Cancer Foundation, UVA rays have a longer wavelength and are more associated with aging. UVB rays, on the other hand, have a shorter wavelength and are more associated with skin burning. Previously, we thought these two effects were separate, but nowadays we know the two effects do overlap.
The longer wavelength of UVA rays penetrate to the deeper layers of the skin and cause damage to the pigment cells, collagen, and elastin, contributing to aging, but have also been proven to contribute to the development of skin cancer. UVA rays are the main type of rays we often think of when we think of commercial tanning beds. But where once we didn’t know the danger of tanning beds, now we know how damaging they can be. They are labeled with Class 1 carcinogen warnings, just like cigarettes.
UVA rays are also all around us. According to the Skin Cancer Foundation, 95% of the UV radiation that reaches the earth is UVA. UVA rays even penetrate windows and clouds, so it’s important to keep that in mind if you are thinking of protection from sun damage and aging.
UVB rays don’t penetrate as deeply but they pack a damage punch. These are the rays that cause sunburns, blistering, and major DNA damage. And you don’t need to be in a warm climate for UVB rays to affect you. At high altitudes or near reflective surfaces like snow and ice, they can do significant damage to your skin.
What is SPF?
While most people know that SPF is important and that it’s on all sunscreen bottles, what does it mean? SPF stands for sun protection factor, and it is the number that rates how well sunscreen filters out UVB rays.
More specifically, according to the FDA, SPF measures how much time exposure to UVB radiation is required to produce a sunburn on protected skin. The higher the number, the more protection. SPF 30 provides more protection than SPF 15, but not exactly twice as much. The number scale is not direct. But a very high SPF does not give total protection. It can give people a false sense of security and have them expose themselves to more sun than is safe, partially because UVB rays still come through, and partially because SPF only refers to protection against UVB rays and doesn’t refer to protection against UVA rays. For that, we are reliant for now on looking for bottles labeled “Broad-Spectrum”.
What is Broad-Spectrum?
When you see “broad-spectrum” on a sunscreen bottle, it means that the manufacturers are claiming that the ingredients have a significant level of protection against a wider ultraviolet spectrum across both UVB and UVA wavelengths.
Early sunscreens only protected against UVB rays, but once we learned how dangerous UVA rays are, the makers of sunscreen added ingredients to ensure their formulas were protecting against both UVB and UVA rays. The broad-spectrum term came about because the sunscreen is protecting against a “broad spectrum” of UV radiation.
Wearing a broad-spectrum sunscreen of at least SPF 30 and staying out of the sun as much as you can is best practice. You will also want to make sure you’re reapplying broad-spectrum sunscreen every 2 hours or more often. If you can, use one rated to be water resistant for up to 80 minutes. According to the Centers for Disease Control and Prevention (CDC), you also need to apply it after swimming, sweating, and when toweling off.
What is UPF?
You may have seen the term UPF+ or “UPF-rated” on certain clothing items. UPF stands for ultraviolet protection factor and measures the protection level a piece of fabric has against UV radiation. More specifically, it measures the level of protection against both UVA and UVB rays.
Since not all fabric has the same level of protection, the UPF rating can tell you how much a piece of clothing can protect you from the sun.
Unfortunately, not all clothing provides this rating. But some brands offer clothing specifically for sun protection, and they will list the UPF rating. They typically will show “UPF-rated” on the label, and if it shows a specific number, the higher, the better. A UPF rating above 40 provides quality sun protection. You can also look out for the Skin Cancer Foundation Seal of Recommendation on the label.
If there is no rating, according to the Skin Cancer Foundation, fabric that is dark or bright in color, densely woven, loose-fitting, and covers the body is more likely to provide quality protection from the sun.
You will also want to be careful with washing a UPF-rated garment. As shown in the Current Problems in Dermatology series, washing clothing can affect how much protection it provides.
Differences Between the SPF and UPF Rating
The major difference between SPF and UPF is in what they rate. UPF exclusively rates the amount of sun protection a fabric provides. SPF measures how much UV radiation sunscreen filters out. You won’t see a sunscreen bottle with a UPF rating on it and you won’t see a piece of clothing with an SPF rating.
Schedule A Consultation
How important protecting your skin from the sun is cannot be overstated. It is vital to ensure your skin stays healthy and youthful-looking.
Are you looking to protect your skin from the sun with a skincare regimen that’s customized to your unique needs? Dr. Krant at Art of Dermatology can address any skin concerns you have and recommend research-tested skincare products that meet your specifications.
To schedule a consultation today, call our New York City office at 212-488-5599 or use our online contact form.
Jessica Krant, M.D., MPH, is a board-certified dermatologist with specialized experience in cosmetic, laser, surgical, and medical dermatology, but above all, Dr. Krant is most proud to be a caring, comprehensive physician who takes the time to listen and send her patients home with a smile.