By: Jenna Trubschenck, PA-C
Clothing can be utilized as a good option in aiding daily sun protection. However, just having a white t-shirt on does not necessarily mean that you are getting total sun protection.
Ultraviolet Protection Factor (UPF) is a standardized measurement of photo protection from the sun. You can think of it like SPF; however, SPF specifically only measures UVB protection (unless specified as broad-spectrum), whereas UPF incorporates both UVA and UVB protection. A shirt with a UPF of 50 will allow only 1/50th of the sun’s UVA and UVB rays to pass through.
Studies show that, in regular clothing, lycra/elastane fabrics are most likely to have UPFs of 50 or higher, followed by clothing with plastic, nylon and polyester. This is far superior protection than a white cotton T-shirt, which has a UPF of about 5 (that’s 1/5th of the sun’s rays that are passing through). It is difficult to tell how protective clothing is just by looking at it, because visible light passing through material can differ from the amount of UVR (UV radiation) that penetrates.
Factors that play into clothing’s UPF factor include:
Weave density – how much of the fabric is actually composed of fibers (as opposed to space through which UVR can pass)
Composition of fabric – synthetic fibers such as polyester, lycra and nylon are more protective than cottons or linen
Color – darker colors tend to be better than lighter colors, as they absorb more UVR
Weight – thicker, heavier clothing absorbs more UVR
Stretch or tension of fabric – the more the fabric is stretched, the lower the UVR rating
Moisture – wet clothing decreases the UPF rating
Fabric condition – the more worn and frayed, the more UVR can pass through
In general, clothing worn in highly UV radiated regions should have a UPF of 50+ (especially when considering water wear, as UPF decreases when clothing is wet).
Everyday clothing can be adequately photoprotective if you pay close attention to the aforementioned factors that contribute to clothing’s UPF rating (jeans have a UPF rating of 1700!). It is also possible to wash in UV blocking agents or sun guard.
For certainty’s sake, UPF-rated clothing allows you to know upfront exactly how much photoprotection you are getting.