Photoprotection properties of clothing measured across ultraviolet and visible wavelengths

This study evaluates the photoprotective performance of commercially available clothing using a spectrophotometer with an integrating sphere. 37 different garments were analysed across multiple spectral protection factors. In addition to ultraviolet protection factor (UPF, 290-400 nm), measurements included UVA protection factor (UVA-PF, 315-400 nm), high-energy visible light protection factor (HEV-PF, 400-469 nm), visible light protection factor (Visible-PF, 400-800 nm), and Protoporphyrin IX protection factor (PpIX-PF, 350-800 nm), providing a broader assessment relevant to photosensitive skin disorders. Spectral transmittance of garments was measured and used to calculate the multiple protection factors across ultraviolet (UV) and visible wavelength ranges. Most garments demonstrated substantial UV protection, including items not marketed as sun protective. Darker fabrics, particularly black cotton and polyester, showed the highest UPF values, frequently exceeding 50, whereas lighter fabrics, especially white cotton, generally offered lower protection (a UPF < 40). Protection was not correlated with garment cost, with some low-priced items providing excellent performance. Dark-coloured garments also offered superior attenuation of high-energy visible light, although transmission increased at longer visible wavelengths across all samples. These findings highlight the limitations of relying on UPF alone to assess textile photoprotection. A multi-spectral approach reveals important differences in protection against UVA, HEV, and visible light, which are clinically relevant for individuals with photosensitivity. This work supports the inclusion of extended photoprotective metrics in textile evaluation and clinical guidance.