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During, July 2000 we used an electronic personal dosimeter (X-2000) and a biological dosimeter (Deutsches Zentrum, fur Luft- und Raumfahrt: Biofilm) to characterize the UV radiation exposure of arctic field scientists involved in biological and geological fieldwork. These personnel were working at the Haughton impact structure on Devon Island (75 degreesN) in the Canadian High Arctic under a 24 h photoperiod. During a typical day of field activities under a clear sky, the total daily erythermally weighted exposure,. as, measured by electronic dosimetry, was up to 5.8 standard erythemal dose (SED). Overcast skies. (typically 7-8 okta of stratus); reduced exposures by a mean of 54%. We estimate that during a month of field activity in July a typical field scientist at this latitude could potentially receive similar to 80 SED to the face. Because of body movements the upper body was exposed to a UV regimen that often changed on second-to-second timescales as assessed by electronic dosimetry. Over a typical 10 min period on vehicle traverse, we found that erythemal exposure could vary to up to 87% of the mean exposure. Time-integrated exposures showed that the type of outdoor field activities in the treeless expanse of the polar desert had little effect on the exposure received. Although absolute exposure changed in accordance with the time of day, the exposure ratio (dose received over horizontal dose) did not vary much over the day. Under clear skies the mean exposure ratio was 0.35 +/- 0.12 for individual activities at different times of the day assessed using electronic dosimetry. Biological dosimetry showed that the occupation was important in determining daily exposures. In our study, scientists in the field received an approximately two-fold higher dose than individuals, such as, medics, and computer scientists, who spent the majority of their time in tents.