Fig. 1.

Solar simulated radiation is primarily composed of penetrating, yet low energy, UVA wavelengths. (a) Normalised spectral outputs of broadband UVB, solar simulated radiation (SSR) and filtered SSR (UVA) sources. The spectral output of SSR (WG320 filtered xenon arc lamp) is composed of 5.0% UVB radiation. Further filtration (with WG345) removes the majority of the UVB component (UVA: 99.6%, UVB: 0.4%). In contrast, the spectral output of a broadband UVB source such as the Philips TL-12 [15] contains UVA (44.3%), UVB (55.3%) and UVC (0.4%) components whilst the output of many UVC-rich sources peaks at 254 nm. (b) Although such 254 nm UVC radiation can influence the epidermis, solar UVB and UVA radiations can penetrate the papillary dermis and subcutaneous tissue respectively (adapted from [31]).