Measurements and modelling of radon infiltration into a dwelling

This paper reports on in situ measurements in a Dutch test dwelling of radon exhalation of walls, floor and soil in and under the dwelling which are interpreted in terms of source strengths. Continuous measurements of radon concentration in various compartments (e.g. crawl space and living room) of the same dwelling together with measurements of leakage parameters, temperature, pressure differences between compartments and ground-water table are used to obtain information on the dynamic aspects of the radon infiltration. Source strengths and dynamic variables are used as input for a multi-room model to describe the variations and interrelations of radon concentrations in various compartments. Despite the relatively low radon concentration in the soil gas (∼10000 Bq.m-3) and low permeability of the soil, preliminary analyses suggest pressure driven flow through the soil to the crawl space to be an important radon source. A possible influence of precipitation on this flow and on the source strength for the soil of the crawl space is discussed. Measurements with forced depressurization of the crawl space indicate an additional entry for radon in the living room. Entry of radon with soil gas into the cavity wall and from there into the living room seems to be a likely path