Lists three factors causing a high radon and radon daughter concentration in Swedish dwellings:< 1. By energy-saving measures the ventilation rate has become low.< 2. 10% of existing houses are built of light-weight concrete with a high proportion of radium.< 3. Large regions have high radium content in the ground.< Describes a method for detecting high radon daughter levels by measuring gamma radiation from the outside.
Reports measurements of radon daughters in air. The daughters were collected on filters for different lengths of time. A silicon semiconductor detector and the etch foil technique were used to measure the alpha particles from the radon daughters. Finds that alpha particle concentrations in living rooms have the same variation with time as outdoors.