Special Aspects of the 222Rn and Daughter Product Concentrations in Dwellings and in the Open Air

Abstract

From more than 150 simultaneous measurements of the 222Rn and 222Rn daughter product concentrations in dwellings and from more than 100 measurements outdoors, information on the equilibrium between 222Rn and its short-lived daughters was obtained. The equilibrium factor indoors, F, was found to be 0.3 ± 0.1; outdoors F was determined to be about 0.4. A correlation analysis of the data obtained showed that indoors the equilibrium factor, F, is fairly independent of ventilation, 222Rn concentraiton and other parameters. Continuous measurements of the diurnal variations of the 222Rn and daughter product concentrations showed that the activity concentrations of both the 222Rn and 222Rn daughter product concentrations in dwellings vary strongly. It could be shown that because of the higher exhalation rates of the outside walls of cellar rooms and their poorer ventilation compared with living rooms, the resulting 222Rn concentrations in cellars will be higher by a factor of 2 than the concentrations observed in normal living rooms.