What’s the best way to protect yourself from the sun’s harmful ultraviolet rays (UVR), given that we need to work, travel, and sometimes play outside? Clothing is the most basic and generally the best means of sun protection. Not all clothing is equal, however, and some of it isn’t actually very good at protecting us. So, what makes a piece of clothing sun-safe?
The sun damage done to every exposed part of your body is cumulative over your lifetime, continually adding to your risks of premature skin aging and skin cancer. So, to put it simply, the more skin you cover, the better. A long-sleeved shirt covers more skin than a T-shirt, especially if it has a high neckline or collar that shields the back of the neck; long pants cover more skin than shorts. A wide-brimmed hat protects more of the face than a baseball cap, and close-fitting wraparound sunglasses protect more of the area around the eyes than small lenses do. Cover up.
Of course, you can have clothing over every square inch of your body, but if the sun goes right through it, it’s not much use. Fabrics are made of tiny fibers woven or knitted together. Under a microscope, we can see lots of spaces between the fibers; UV can pass directly through these holes to reach the skin. The tighter the knit or weave, the smaller the holes and the less UV can get through. Twill, used to make tweeds or denim, is an example of a tightly woven fabric. Open weave fabrics provide much less protection.
Fabrics can be made from many types of fibers, including cotton, wool, and nylon. Most fibers naturally absorb some UV radiation, and some have elastic threads that pull the fibers tightly together, reducing the spaces between the holes. Synthetic fibers such as polyester, lycra, nylon, and acrylic are more protective than bleached cottons, and shiny or lustrous semi-synthetic fabrics like rayon reflect more UV than do matte ones, such as linen, which tend to absorb rather than reflect UV. Finally, consider the fabric’s weight and density — light, sheer silk gauze will provide far less UV protection than heavy cotton denim.1,2,3