Radon exhalation from the ground; method of measurements and preliminary results

The paper will present a method for measurements of radon exhalation from the ground. The method is based on a combination of activated charcoal and TLD. This method is superior to the traditional charcoal method, because it yields a mean value for the exhalation rate during the whole in-growth time. Furthermore, by using the activated charcoal/TLD method, the decay time is not critical, because the TLD is irradiated from absorbed radon during the decay time. In this way, the method is usable for remote measurements by mail. The method has been tested in areas with "normal" ground and in areas where high indoor radon concentrations previously have been measured. Exhalation measurements were performed near to houses where the indoor radon concentrations were known, and in most cases there was a strong correlation between exhalation rate and indoor radon concentrations. The method thus seems to be usable for classification of building ground.