1970 年 39 巻 2 号 p. 114-118
The filter pack method used for measuring the radon concentration in air is described. We may estimate the radon concentration by this method assuming radioactive equilibrium among radon and its daughter products. The absolute collection efficiency of a millipore filter whose pore size was 0.3 microns was examined, and it was clarified that the filter collects almost perfectly radioactive aerosols in the air. The radon concentration in the air was measured simultaneously by the charcoal trap method and the filter pack method. The filter pack method was found to be fairly useful for measuring radon concentration in the air.