The distribution of biologically effective UV spectral irradiances received on a manikin face that cause erythema and skin cancer

Solar ultraviolet (UV) radiation is a major cause of erythema and skin cancer in humans and the face is one of the highest risk sites. Biologically effective UV irradiation (UVBE) is wavelength-dependent, and risk assessment has been demonstrated based on the value of the received UV radiation. Therefore, this study measured the face skin exposure to UV spectral irradiance using a spectroradiometer and a head manikin, which were weighted by action spectra to calculate the UVBE that causes erythema (UVBEery), non-melanoma (UVBEnon-mel), human squamous cell cancer (UVBEh-SCC), and DNA damage (UVBEDNA-d). We determined that the biologically effective UVB and UVA irradiances on clear sky days had peak values at 65–73° SEA (8–9 UVI) and 55–68° SEA (6–7 UVI), respectively. In the 10–30° SEA range, the highly skin-damaging wavelengths were all observed at 300 nm. However, in the 30–60°, 60–81°, and 10–81° SEA ranges, the highly skin damaging wavelengths were 300 nm, 304 nm and 300 nm for UVBEery, respectively; 304 nm, 306 nm and 304 nm for UVBEnon-mel, respectively; all 305 nm for UVBEh-SCC, and two small peaks at 302 nm and 312 nm for UVBEDNA-d.