Comparison of sun protection factors obtained with a xenon solar simulator and an Ultravitalux lamp.

The influence of the type of UV source on the sun protection factor (SPF) was investigated in healthy volunteers with skin Types I to III. In an open-paired comparison, sunscreens with low, medium and high SPF were examined under identical test conditions using either a 150-watt xenon-arc solar simulator or a set of four 300-watt Osram Ultravitalux bulbs as the UV source. Despite wide differences in the spectral output of the two sources, both yielded similar mean SPF for each of the three test sunscreens. The only significant difference observed was with the FRG standard, for which a lower mean SPF (3.1) was obtained with the Ultravitalux lamps compared to the solar simulator (mean SPF 4.0). There were no differences between the calculated arithmetic and geometric means.