EXPOSURE TO NATURAL SOURCES OF RADIATION IN SPAIN

Studies carried out by us over the last 3 yr have produced a map of natural radiation for Spain. The map contains the respective contributions of outdoor and indoor terrestrial gamma-rays, of cosmic-rays and indoor radon, shown by administrative region. Terrestrial gamma-rays were measured outdoors in situ at more than 1000 locations. Data for indoor gamma-rays were derived from the radioactive content of the most typical building materials used in Spain and by in situ measurements in approximately 100 houses. The cosmic-ray component was calculated according to latitude and altitude. Values for indoor radon exposure were derived from a national survey, which covered more than 2000 individual measurements employing active and passive detectors. By taking account also of other exposures, the mean annual effective dose equivalent from these and the sources under study has been evaluated. Doses from thoron decay products and internal exposure are not dealt with in this evaluation.