Karst Geology, Radon Fluctuations, and Implications for Measurement and Mitigation
Authored by:Jack R. Hughes, Brad Turk, Robby Cardwell, Patsy Brooks, Gene Fisher,
Marsha White, Francis Fitzgerald, David Wilson, James O. Bryant, Jr.
Abstract:
Results of an investigation into factors contributing to elevated indoor radon concentrations in supposedly mitigated homes suggest that, in areas of extensive karst geological development, fluctuations in indoor radon concentrations may be extraordinary in magnitude, duration and seasonal occurrence. Long-term monitoring of radon concentrations and other building and environmental parameters indicate that the dominant factor producing these variations is the temperature difference between the ground and ambient air, acting with elevation gradients to cause movement of radon-bearing soil gas through the karst formation. The extreme nature of these variations may necessitate alternative measurement strategies and mitigation procedures to reduce 'false negatives' and 'false positives' and to enable effective reduction of indoor levels.
Intensive diagnostic investigations of the study houses were carried out, and procedures were developed to predict and simulate mitigation system mechanical performance. The investigation continues with efforts to evaluate various measurement strategies.
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