Radon in dwellings: a high-voltage method for a fast measurement of radon daughter levels

Indoor concentrations of alpha -emitting radon daughters can be measured by a high-voltage method. The alpha -active atoms usually stick to charged dust particles which can be collected using a long wire (2.1 m) given a negative potential (-5 kV). Such an electrostatic method will influence the air streams in the room less than if the collection were arranged by pumping air through a filter. The alpha counting rate can by calibration be transformed to a radon daughter level in Bq m -3 . A high radon daughter level in a dwelling is caused by the emission of an inert gas, radon, either from building materials or from the ground. The contributions of 'wall radon' and 'ground radon' can be estimated by measuring both the gamma radiation and the radon daughter level.