Ultraviolet Radiation Protection by Clothing: Comparison of In vivo and In vitro Measurements

The protection provided by clothing against solar ultraviolet radiation (UVR) has been the subject of considerable recent research. In general, rated clothing is tested according to standards using laboratory based in vitro measurements of the fabric spectral UVR transmittance and weighting this with the erythemal effectiveness of the CIE (1987) to determine an Ultraviolet Protection Factor (UPF). While in vitro test methods provide a precise determination of protection, there were some concerns they could overestimate the protection in comparison to in vivo measurements. This paper details a comparison of UPFs derived from the in vitro tests for 16 fabric samples against in vivo SPF tests. Agreement between the two sets of results is very good, with no statistically significant difference between the two data sets and with only one misclassification of protection category between the SPFs and UPFs.