Numerical modelling is a powerful tool for studies of soil gas and radon-222 entry into houses. It isthe purpose of this paper to review some main techniques and results. In the past, modelling hasfocused on Darcy flow of soil gas (driven by indoor-outdoor pressure differences) and combineddiffusive and advective transport of radon. Models of different complexity have been used. Thesimpler ones are finite-difference models with one or two spatial dimensions. The more complexmodels allow for full 3D and time dependency.
Soil radon concentrations together with climatic and seismic data were continuously observed in theKanto area (Japan). During fall 1998, several typhoons and earthquakes occurred. In the meanwhile,continuous measurements of the following parameters were carried out: air pressure, temperature inthe air and in the soil, humidity in the soil, wind speeds, wind direction, rainfall and earthquakesmagnitudes.Data were analyzed using time-series analysis method, i.e. Correlation and Spectrum Analysis, so asto point out the possible relationship between radon and an environmental variable.