Predicting the Rate of 222Rn Entry from Soil into the Basement of a Dwelling Due to Pressure-Driven Air Flow

Abstract

Abstract A combination of analytical and numerical methods is applied to the problem of computing 222Rn transport from soil into a dwelling having a basement. Transport is assumed to occur solely by pressure-driven air flow, and the basement shell is assumed to have a single dominant leak that is uniformly distributed around the perimeter at the level of the floor. The results show that for small flow rates of air through the soil, the radon entry rate into the basement increases in proportion to ?Po, the outdoor-indoor pressure difference at the soil level. For large flow rates, the entry rate increases only in proportion to ?Po2/3, due to depletion of radon concentration in the soil. A sample calculation indicates that via this transport mode, soil having ordinary 226Ra content and moderately high permeability can be responsible for indoor radon concentrations of the order of 500 Bq.m-3, greater than recommended guidelines for new housing.