| Abstract: | A dedicated research house is used to investigate the interactions of the house, and atmosphere on indoor radon concentrations. Semi-diurnal variations of atmospheric pressure, resulting from atmospheric tides, are observed to produce differential pres- sures capable of driving radon-containing sail gas into slab-on-grade structures built over low permeability soils. These naturally induced pressure differentials could continue to provide major contributions to radon entry when other sources of house pressurization or depressurization, and consequently outdoor air infiltration rates, are small. The observed driving force pressure differentials are well predicted from atmospheric pressure changes by a simple model based on an exponentially damped response of the sub-slab pressures to changes in atmospheric pressure. The observed radon entry rates are in good agreement with the predictions of radon entry models developed by other investigators when time-averaging of the driving forces is applied. |
