Radon-Reporter-2026-Issue-1FINAL

THE RADON REPORTER | 21 along the vent-facing wall. Due to elevated radon levels in soil gas, continued confirmation of air tightness, both inside and along the vent-side of the home, is critical when the fan is mounted indoors. Overall, despite conflicting information, sidewall venting inherently elevates local outdoor radon concentrations and increases the possibility (compared with roof-level venting) of radon re-entrainment back into living spaces of the emitting house and its neighbors. Radon concentrations along the side of the emitting house can be quite high near the exhaust vent, and air exchange into the house from nearby open windows or air intakes can increase indoor concentrations, depending on atmospheric stability conditions. As the emphasis has been to reduce radon exposures in homes, schools, and workplaces, it seems counterproductive to allow side-wall venting in the U.S. The increased potential for radon exposure is unnecessary. Except for the health-implications of freeze-ups, criticisms of above-roof venting have been economically based (materials, repairs). From an economic viewpoint, the materials and labor needed to exhaust above the roof line, or at least above the breathing zone, are inconsequential relative to the cost of even a single lung cancer case in the neighborhood. Mike Kitto, Retired from the NY State Department of Health Labs; Jane Malone, IEA National Policy Director; Kim Steves, Retired from the KS State Department of Health and the Environment. They serve on the Indoor Environments Foundation’s Board of Directors. References Bernier, James and Brossard, Mathieu (2014) Outdoor Radon Dispersion: Comparison of Lateral vs Vertical Exhaust of Radon Sub Slab Depressurisation Systems. CARST Radon Conference, Mississauga, Canada. Brodhead, Bill (2020) Measuring At-Grade Radon Mitigation Exhaust. International Radon Symposium, virtual meeting . Brossard, Mathieu; Brascoupe´, Marcel; et. al. (2012) Residential Radon Mitigations at Kitigan Zibi Anishinabeg: Comparison of Above Ground Level (Rim Joist) and Above Roof Line Discharge of Radon Mitigation Sub-Slab Depressurization Systems. Health Physics 2012 May;102 (5 Supplement 2):43-47. Henschel, D. Bruce (1995) Re-Entrainment and Dispersion of Exhausts from Indoor Radon Reduction Systems: Analysis of Tracer Gas Data”, Indoor Air, 5(4), 270-284. KSU (2022) https://mediasite.k-state.edu/Mediasite/Play/97dc4bc3ebf34c3eaeb0e0e3152123cc1d?playFrom=25068 &popout=true Posted Jan 4, 2022. Lebel, Luke; John. Aneesh; Korolevych, V.Y. (2021) Dispersion Simulations of Radon Discharges between Neighboring Buildings and Their Sensitivity to Meteorology, Discharge Rate, and Building Geometry. Health Physics, Lebel, Luke; Vu, Kim; John. Aneesh; Korolevych, V.Y. (2022) Method for assessing radon Re-Entrainment risks from above ground level discharges from sub-slab depressurization systems, Building and Environmen t 215(2), 1-18. Lewis, Robert; Bleiler, Denise; et. al. (2025) Radon Re-Entrainment Study – An Initial Investigation, Health Physics 128(6), 467-475. Maeda, Lori Y. and Hobbs, Willard E. (1996) Outdoor Radon Concentrations in the Vicinity of an Active Home Radon Mitigation System, 1996 International Radon Symposium, Haines City, FL Neff, David E.; Meroney, Robert N.; and El-Badry, Hesham (1994) Physical and Numerical Modeling of ASD exhaust Dispersion Around Houses. EPA/600/SR-94/115. RESEARCH