Effectiveness of a Passive Subslab Ventilation System in Reducing Radon Concentrations in a Home

• Published in: Environmental science & technology Vol. 30; no. 10; pp. 2914 - 2920
• Main Authors: Holford, Diana J, Freeman, Harley D
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.10.1996
• Subjects: Applied sciences; Atmospheric pollution; Chemistry; Exact sciences and technology; Houses; Indoor pollution and occupational exposure; Measurement; Pollution; Radon; Ventilation; Performance evaluation; Radioactive pollution; Radon; Indoor pollution; Numerical simulation; Ventilation; Housing; Modeling
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es950790q

The effectiveness of a passive subslab ventilation system in reducing radon concentrations in an occupied home was investigated by measuring radon concentrations and pressure differentials during a 1-year period when a passive subslab ventilation system was being cycled on and off. Radon concentrations in the house were 30% lower during periods when the stack was open to the atmosphere. This effect was most pronounced when the home was unoccupied and during the winter and spring months. Furnace use and wind speed were the best predictors of transient changes in basement radon concentrations, whether the stack was open or closed. Pressure differential measurements show that subslab depressurization oc curs when the stack is open during the winter and spring months due to bouyancy-driven air flow up the stack, but not during the summer. Numerical simulations of gas flow and radon transport into the house from the surrounding soil were calibrated to observed pressure differentials and radon concentrations. The model predicts that peak radon concentrations caused by furnace use will be reduced by flow out of the stack. However, the model is unable to account for the reduction in average radon concentrations observed while the stack is open in the winter.