Assessment of integrated solar ultraviolet radiation by PM-355 detectors

The increase in environmental solar UV radiation due to depletion of ozone layer is a recent challenge to human health (skin cancer and eye effects) i n countries having clear skies. Therefore, applying integrated, passive and inexpensive techniques to assess solar UV radiation is very much essential . Measurements of environmental solar UV radiation in Dhahran, Saudi Arabia area were carried out for a period of two months in the summer period in 1 996 using two techniques in parallel namely: passive nuclear track detector s and active solar UV radiometers. Some of the nuclear track detectors were mounted in different conditions such as: under shadow band, on solar track ing mechanism following the solar rays. Others were mounted on perpendicula r, tilted and horizontal surfaces in sunlight. All detectors were attached to a wooden background of the same thickness (0.5 cm) to eliminate interfer ence of the heat effect of various support materials and have uniformity of the support materials. The assessment was carried out for different period s extending from two to nine weeks continuously. The investigated period co vered the hottest months in Saudi Arabia (July and August) when the sky was clear of clouds. The results indicate linear correlation between alpha tra ck diameters and the integrated exposure to solar UV as measured by the sol ar UV radiometer for all nuclear track detector positions and orientations. The highest slope has been observed for the detectors placed on solar trac king mechanism following the solar rays and the lowest from detectors orien ted under the shadow band on horizontal position (measuring the diffused UV radiation only). The results show that most of the measured UV radiation ( 60%) were from the diffused UV radiation. The characteristics of the upper layer of the detectors are changed after chemical etching very quickly, wit h increase in the exposure time to UV salar radiation at certain orientatio n. The results encourage the use of nuclear track detectors for environment al and personal solar UV dosimetry on a large scale in Saudi Arabia and sim ilar hot and clear-sky countries. (C) 2000 Elsevier Science Ltd. All rights reserved.