As dermatologists, we probably talk more than anyone else about the danger of sun exposure– after all, we see its effects firsthand every day. By now, most people are aware of the importance of using sunscreen daily, but here at Arizona Dermatology, we’ve been telling our patients about another powerful tool to protect against skin cancer– UPF clothing.
What is UPF clothing?
UPF stands for Ultraviolet Protection Factor, similar to SPF for sunscreen. While SPF refers to the amount of protection a topical sunscreen offers from UVB rays, the UPF factor describes how much protection a piece of clothing offers from both UVA and UVB rays.
As with SPFs, the higher the number, the more protection.
What amount of protection does UPF clothing provide?
UPF clothing is specifically engineered to provide maximum protection from UV rays and may be rated from 15 to 50+. The rating refers to the fraction of UV radiation that is able to pass through the material. For example, a shirt with a UPF of 50 lets only 1/50th of the sun’s UV rays penetrate through, offering a formidable shield against damaging UV radiation.
Of course, any type of clothing will give some amount of sun protection, as you can see when you wear a T-shirt over your bathing suit (generally speaking, a T-shirt offers a UPF factor of about 5, meaning it allows about 20% of the sun’s radiation to pass through).
A UPF factor of 15-20 is considered “good,” allowing only 4.2%-6.7% of ambient UV radiation to penetrate the fabric. A rating of 25, 30, or 35 is considered “very good,” allowing only 4.1%-2.6% through. Factors of 40, 45 and 50 protect from all but about 2.5% of the sun’s UV rays. And anything that allows transmission of less than 2% of UV radiation is labeled 50+.
Clothing with a UPF of 15 or less is not considered UV-protective.
How does UPF clothing work?
Several factors affect the UPF rating of an article of clothing.
Construction. If you look at a piece of material under a microscope, you’ll note how close together the threads are and how much light passes through the spaces between them. In the same way, more UV radiation passes through looser weaves, while tighter weaves provide more protection. Thicker materials keep out more UV rays as well.
Fiber. Synthetic materials such as polyester and nylon generally provide greater protection against UV rays than natural fibers. Wool and silk offer better UV disruption than cotton. Rayon, although synthetic, typically scores low.
Color. Darker colors absorb more UV light than lighter colors. A bright shade of the same color is more protective than a pale shade.
Treatments. Chemicals or dyes may be added to UPF clothing to help absorb UV rays.
As UPF clothing ages, it may lose some of its effectiveness. Clothing that is faded or stretched out will let in more UV radiation that it did when it was first purchased. UPF clothing that has been treated with a chemical will lose some of its effectiveness as the chemical is washed out over time (check labels to see if the item is advertised to withstand a certain number of washes). It is also important to note that many types of clothing lose significant UPF points when wet (that’s why many UPF options are made with fast-drying materials.) Curiously, polyester appears to be the one fabric which may actually provide more protection when wet.
What are some common types of UPF clothing?
Rash guards. Probably the most common type of UPF clothing, these popular swim shirts are usually made of synthetic material and come in both short and long-sleeve versions (we recommend the long sleeve). They are great for kids and adults alike.
Sportswear. Whether you are a watersports enthusiast or a mountain hiker, outdoor clothing companies like Patagonia are offering UPF clothing, including long-sleeved UPF shirts, hoodies, and even hiking pants.
Daily wear. As it gains popularity, UPF clothing has become more stylish as well. Coolibar is a popular UPF brand offering clothing in a variety of styles for men, women and children, including dresses, tops, bottoms, gloves and sleeves, swimwear and more. Other popular clothing manufacturers such as Lilly Pulitzer and Athleta now offer UPF lines as well.
If you prefer chemical-free UPF clothing, there are companies such as Nozone and Solartex that specifically offer UPF clothing without added treatments.
Of course, it’s important to remember that UPF clothing only protects the skin that it covers! To fully protect your skin, don’t forget to use sunscreen on exposed areas, wear a wide-brimmed hat, and limit time in the sun during the hottest times of the day.