[en] Distribution of ²²⁶Ra activities and ²²⁸Ra/²²⁶Ra activity ratios were measured in the surface waters of the Irish Sea and in the English Channel. ²²⁶Ra activities vary from 0.001 Bq.1^-1 for the Atlantic water to 0.002 Bq.1^-1 for coastal waters, whereas ²²⁸Ra/²²⁶Ra activity ratios increase from 0.18 to 2.18. The coastal waters are clearly dominated by radium injection from nearshore sediments. (author)

[en] Full text: The principal source of exposure to radiation for public in built-up areas is known to be the inhalation for radon its short-lived daughters.Most of this exposure occurs inside homes,where many hours are spent each day and where the volumic activity of radon is usually higher than outdoors. The compelling effects of radon and its short-lived decay products spread slowly but surely through a wide range of biological problems encountered in such areas as the mortality rates and lung cancer in uranium mines,the results of experimental work with animals, and the discovery of unsually high levels of radon in the living environments of the general population. As a way of prevention, we have measured the volumic activities of indoor radon-222 and we have calculated their effective equivalent dose in some dwellings and enclosed areas in Morocco. The obtained results show that the effective equivalent dose of activities measured indoor dwellings are inferior to the admissible annual limit fixed by ICRP for population, except in two twons situated in regions rich in phosphate deposits where the calculated doses are slightly upper than this limit. The results obtained for enclosed areas are inferior to the admissible annual limit fixed by ICRP for workers, except in the cave of geophysical observatory situated at depth of-12 meters where the obtained value don't present in risk for workers health because workers pass only a few minutes by day in this cave. The risks related to the volumic activities for indoor radon could be avoided by simple precautions such the continuous ventilation