Defining the convective driving force for soil gas intrusion into houses.

One exposure pathway which has a significant influence on the outcome of a site specific risk assessment when volatile contaminants compounds are involved, is the leakage of contaminated subsurface gases into the indoor air environment. Evaluation of this pathway largely is completed with the use of mathematical models. The current level of understanding is that both convective and diffusive contaminant transport processes in the soil and across the subsurface building envelope will contribute to degraded indoor air quality.