Ultraviolet Protection Factor Clothing
Learn about the science behind sun protective clothing
Edited By:Raja Sivamani , MD MS AP
Your skin is your largest organ and regardless of the weather or season, your skin is exposed to the sun's harmful rays daily. There are nearly 3.7 million skin cancers diagnosed in the US annually, which is more than any other type of cancer combined. We know that the vast majority of skin cancer is caused by UV radiation (UVR). We also know that up to 90% of the visible changes commonly attributed to aging including wrinkles, sagging skin, and brown spots are also caused by UVR. So what is the most effective way to protect your skin? In an “ideal” scenario you are armed with sun-protective clothing, a wide-brimmed hat, sunglasses, and sunscreen, but since “ideal” isn’t always realistic make clothing your top priority. The Skin Cancer Foundation ranks clothing as THE single most effective form of sun protection. I am in agreement. Sun damage to exposed skin is cumulative over your lifetime, contributing to your risk of premature skin aging and skin cancer. By limiting the amount of skin exposure via protective clothing, you minimize your risk.
As with many things, success is achieved through the collaboration of multiple factors to produce a better end product. Take, for instance, winemaking as an example. The creation of a fine wine is dependent on certain factors including the varietal of grapes used, the light, temperature, and soil conditions affecting the grapes and vines respectively, the length of the fermentation process and yes, you guessed it the skin. Similar to creating fine wine, creating clothing that can provide sun protection requires integral factors be present in its basic construction. These factors include tightness of weave or knit, type of fiber, thickness or density of a material, and color.
UVR can pass directly through the spaces between woven or knitted fibers in the fabric. Therefore, the tighter the knit or weave, the smaller the spaces between fibers and the less UVR getting through. Wool or twill (used to make denim) are examples of tightly woven fabrics that provide excellent protection, compared to a fabric like lace, a loose weave fabric which provides little protection. With regard to fiber type, both composition and texture lend themselves to greater or lesser protection. For example, a fabric composed of synthetic fibers such as polyester, lycra, and nylon offer greater protection than cotton. Compared to matte fabrics like linen which tend to absorb UVR, shiny semi-synthetic fabrics like rayon reflect more UVR and provide greater protection. When considering the fabric’s weight and density, it is the heavier and thicker fabric that will absorb more UVR. Think of a denim shirt compared to a gauzy silk blouse. Color is integral to determining the degree of protection a garment provides with darker or more intense colors like red absorbing more UVR than pastels.
Taken together, the synergy of these factors lend themselves to a qualitative measure of their ability to provide sun protection referred to as UPF (Ultraviolet Protection Factor). UPF ratings indicate how much UV can penetrate the fabric. For instance, a shirt with a UPF of 50 allows just 1/50th of the sun’s UV radiation to reach your skin which is considered excellent protection. Of note, your basic cotton t-shirt provides a UPF 5. Keep in mind that this can decrease as both the tension on the fabric (stretch from tight-fitting clothing) and moisture can decrease the UPF rating of any fabric.
So what do you do when heading outdoors and want to play it safe? Keep it simple: cover up as much of your exposed skin with loose-fitting, lightweight, tightly woven fabrics in darker colors. If you can find UPF rated clothing that fits your style choose UPF 30-50 to provide you with the best protection.
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