Photoprotection by clothing is one of the most effective protective measures against solar ultraviolet radiation (UVR), and the related concept of UV protection factors (UPF) for fabrics has proven itself for decades. Although immense work has been carried out regarding factors influencing textile sun protection, the idea of UPFs for artificial UVR, if necessary with different action spectra, is payed little attention. In this work, a modified UPF equation is proposed utilizing welding arcs and the ICNIRP action spectrum. These welding UPFs (wUPF) were calculated for some workwear as a function of welding power, technique and welded material. No wUPF welding power dependence existed. By means of normalized standard emission spectra, that were further clustered with regard to welding technique, it was found that the wUPF depends exclusively on the fabric’s transmittance and the ICNIRP weighting function yielding a reduced wUPF formula. Finally, a comparison of solar and welding UPFs, based on either their full or reduced equations, is discussed.
Ultraviolet protection factors (UPF) for clothing are based on the solar ultraviolet radiation (UVR) spectrum in conjunction with the CIE erythema weighting function and consider the textile’s UVR transmittance for wavelengths above 290 nm. However, workwear exposed to welding arcs that emit significant UVR at shorter wavelengths has to fulfill additional textile photoprotection criteria. Therefore, a welding UPF (wUPF) is proposed taking into account the welding arc’s full UVR emission spectrum and ICNIRP’s relative spectral effectiveness for UVR hazards. Analyzing the new protection factor regarding welding power, technique and welded material led to a reduced wUPF equation.