LABORATORY TESTING OF UV TRANSMISSION THROUGH FABRICS MAY UNDERESTIMATE PROTECTION

Laboratory testing of the ultraviolet protection factor (UPF) provided by fabrics normally utilizes a collimated source of UV radiation and either a broadband sensor or spectroradiometer to detect the radiation , both unattenuated and after passing through the fabric sample held i n a fiat tensionless state. We report the results of an in vivo study of UV transmission through various T-shirts at several sites on the tr unk and arms of a life-size mannequin irradiated with diffuse radiatio n and using UV sensitive polymer films as the sensor. We found a varia tion in UPF by a factor of two or more at different anatomical sites f or a given T-shirt, with lower UPFs seen at sites where the fabric is stretched; and found that at every site and for each T-shirt this in v ivo UPF was higher than the conventional in vitro UPF determined using collimated radiation.