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PHOTOPROTECTIVE CLOTHING
The broad range of textiles used in the manufacture of clothing results in highly variable degrees of sun protection. While other countries have mandated the testing required for the labeling of textiles claiming to be photoprotective, no US governmental agencies have regulatory control of such testing. However, the Federal Trade Commission does have the authority to regulate advertising claims regarding the sun protection of textiles.
The European Committee for Standardization published the methodology for determining the UV Protection Factor (UPF). It is based upon in vitro spectrophotometric measurements and standards whereby apparel textiles with a UPF >40 (similar to SPF) are labeled โUPF 40+โ. In addition, UVA transmission needs to be <5%. In the US, textile industry organizations have developed a similar system that covers both UVB and UVA protection. Labeling includes the UPF plus a descriptor, from Good UV Protection (UPF 15โ24) to Excellent UV Protection (UPF 40โ50+); ratings <15 are not allowed.
Important factors that determine the protection afforded by a given textile include fabric porosity, type, color, weight, and thickness as well as the addition of absorbers. In the absence of UPF ratings, porosity is probably the most important factor, with the tighter the weave the greater the protection.