BEHAVIOR OUTDOORS AND ITS EFFECTS ON PERSONAL ULTRAVIOLET EXPOSURE RATE MEASURED USING AN AMBULATORY DATALOGGING DOSIMETER

We describe the construction of a small device incorporating a UVB (29 0-320 nm) sensor that can be worn on the lapel site or waistband and w hich is electrically coupled to a portable data logger carried in a tr ouser pocket or worn on a belt. The detector has an approximate cosine -weighted angular response and is linear over a wide dynamic range. It has a spectral sensitivity that follows closely the erythema action s pectrum in the UVB region, is less than one order of magnitude greater than this action spectrum in the UVAII region (320-340 nm) and betwee n one to two orders of magnitude greater in the UVAI region (340-400 n m). The instrument has been used to monitor variations in erythemally effective exposure rate that occurred during three outdoor activities with differing weather conditions. Erythemal irradiance incident on th e trunk was recorded every 2 s for periods ranging from 1 to 2.2 h. Th e results demonstrated that behavior outdoors can be a more dominant f actor in determining personal exposure than ambient ultraviolet and hi ghlighted the very important role that shade from trees plays in reduc ing exposure.