Indoor Radon Prevention and Mitigation

Abstract

Indoor radon risk reduction depends on the extent and effectiveness of prevention strategies included in the design and construction of new buildings and the mitigation or remediation of radon in existing buildings. The specific techniques used for indoor radon control depend on the mix of radon sources and radon transport mechanisms as well as the design, construction, and operation of the building(s). The primary radon source is predominantly the soil and the underlying geology, and radon is mainly transported from the soil to the indoor occupied space due to air pressure differences. Occasionally, radon may be transported by diffusion, emanation from building materials, or well water. The principal way indoor radon concentrations are controlled is by reversing the air pressure relation between the soil and the indoor space via either active or passive soil depressurization (ASD or PSD). ASD has a continuously operating fan whereas PSD relies upon thermal buoyancy to change air pressure relationships. ASD produces greater and more reliable radon reduction than PSD. The vast majority of mitigation techniques use ASD whereas PSD may be used in new construction. In schools and large buildings, ventilation systems may be used to reduce radon entry due to pressurization of the indoor space.