Measurements of volumic activity of radon in indoor air in dwellings and enclosed work areas in Morocco

The principal source of exposure to radiation for public in built-up areas is known to be the inhalation of radon and 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 are usually higher than outdoors. For measure these volumic activity, cellulose nitrate films LR-115 type II already calibrated of volumic activity of radon are used. The measurements were performed in 30 dwellings and enclosed work areas in different regions of Morocco. The volumic mean activity obtained in dwellings is 64 +- 5 Bq/m sup 3 in Rabat, 59 +- 6 Bq/ m sup 3 in Kenitra, 124 +- 8 Bq/ m sup 3 in youssoufia and 136 +- 9 Bq/ m sup 3 in Khouribga. It was showed that the volumic activity of radon are more higher in two factory locals of moroccan ores treatment than in dwellings. The average volumic activity of radon in geophysical observatory cellar in Berchid was 1541 +- 64 Bq/ m sup 3. We also observed that the volumic activity of radon in indoor air is more higher in winter than in summer and it decrease with altitude and increase with depth. 4 tabs. 2 refs. (author)