The Measurement and Analysis of Solar UVB Irradiance and its Application to the Photoclimatherapy Protocol for Psoriasis at the Dead Sea, Israel

The Dead Sea basin offers a unique site to study the attenuation of solar ultraviolet radiation, as it is situated at the lowest terrestrial point on the earth, about 400 m below sea level. In view of its being an internationally recognized center for photoclimatherapy of various skin diseases, it is of interest to study both its UV intensity and attenuation as a function of wavelength relative to other sites. In order to provide a basis for inter-comparison of the solar radiation intensity parameters measured at the Dead Sea, a second set of identical parameters are measured simultaneously at a second site (Beer Sheva), located at a distance of ca. 65 km to the west and situated above sea level. The existing database consists of measurements from January 1995 to the present. The results of this on-going research project will be presented and the relevance of these findings with regard to the success of photoclimatherapy at the Dead Sea medical spas.

In addition, the broad-band normal incidence UVB beam irradiance has been measured at Neve Zohar, Dead Sea basin, using a prototype tracking instrument composed of a Model 501A UV-Biometer mounted on an Eppley Solar Tracker Model St-1. The application of the results of these measurements to the photoclimatherapy protocol for psoriasis patients at the Dead Sea medical spas is now under investigation. The suggested revision would take advantage of the very high diffuse fraction by allowing the patient to receive the daily dose of UVB irradiance without direct exposure to the sun, viz., receive the diffuse UVB irradiance under a sunshade. This would require an increase in sun-exposure time intervals, since the UVB irradiance intensity beneath a sunshade is less than that on an exposed surface.