Research works on the atmosphere radon and its' daughters have been carried out. The correlations among the concentrations of unattached 218Po and 218Po ions, the number and size of condensation nuclei, and the effective attachment coefficients were clarified. The variations of radon and thoron concentrations were analyzed in relation to the wind speed and turbulent diffusivity.Outdoor and indoor 222Rn concentrations in Japan and China have been surveyed using passive electrostatic integrating 222Rn monitors. The annual mean outdoor 222Rn concentrations ranged from 2.4 to 9.7 Bq m-3 and 4.8 to 14.6 Bq m-3 in Japan and China, respectively. The ratios of indoor and outdoor 222Rn concentrations were about 2 to 3. Outdoor 222Rn concentrations were measured continuously with ectrostatic radon monitors at six locations in Japan and China. The 222Rn concentrations at Nagoya, Kasugai, Toki, Beijing and Fuzhou showed a diurnal variation clearly in autumn. At Kanazawa, the clear diurnal variation appeared in summer. An analytical model of one layer long range transport of "background component" of 222Rn was proposed using air mass trajectory technique. This model could explain the temporal variation of background component of 222Rn. In addition, a three-dimensional numerical simulation model was developed for calculating the temporal variation of 222Rn. The variation of observed 222Rn concentration agreed with that of calculated one.
Ikebe et al. (Fri,) studied this question.