In general measurements of UV-radiation are taken on horizontally orientated surfaces as e.g. for the internationally standardized UV-index (UVI). For relevant assessment of UV-exposure of the human body or specific parts of the skin, however, data of UV radiation fluxes in the directions of the human surfaces is needed.

In the frame of the Bavarian Research Network BayForUV we carry out continuous measurements of erythemally effective UV-radiation on inclined surfaces during two years. The measurements are done with three new self-developed measuring systems (ASCARATIS), each allowing to scan automatically 27 different spherical angles within two minutes. The measurements are made at six sites in Bavaria: on mountain "Zugspitze" (2700 m.a.s.l.), mountain "Hohenpeissenberg" (1000 m.a.s.l.) as well as in the cities of Munich (500 m.a.s.l.) and Würzburg (200 m.a.s.l.) each in the center and in the outskirts. The routine measurements have started in August 2000 at the site Zugspitze and will be finished in September 2002. First results from clear days show that UV-indices measured on a 45° inclined surface (comparable with bridge of the nose) or on a vertical surface (e.g. back), can exceed those on a horizontally orientated surface by about 70% around noon. Thus, large sections of the skin of a standing person receive much higher UV-irradiation intensities than UVI, related to a horizontal surface, would indicate.

The measured UV-data on inclined surfaces will be used to create UV-irradiation maps of the human body.

Sponsored by Bavarian Research Network BayForUV and Environmental Research Station Schneefernerhaus