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Fluctuation of Indoor Radon and VOC Concentrations Due to Seasonal Variations
Citation:
Schumacher, B., J. H. ZIMMERMAN, R. Truesdale, AND C. Lutes. Fluctuation of Indoor Radon and VOC Concentrations Due to Seasonal Variations. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R/12/673, 2012.
Impact/Purpose:
This EPA project report will be used by OSWER to improve vapor intrusion guidance documents currently being prepared and reviewed as well as for guidance document updates in the future. The information provided in the report fills in knowledge gaps identified by the Program Offices, in particular for this report, on seasonal variations of radon and VOC concentrations which are important considerations in VI monitoring and modeling. The extensive database of measurements throughout a year and a half or more cycle will provide OSWER, as well as other VI research professionals, with data and information to put into their modeling efforts to better understand the movement and driving forces of vapors into a residence and, ultimately, the exposure to the residence’s occupants.
Description:
This research was conducted to better characterize the spatial and temporal variability of vapor intrusion by collecting a full year’s dataset of weekly measurements of subslab soil gas, external soil gas, and indoor air, on a single house that is impacted by vapor intrusion of radon and VOCs. By examining both short-term and long-term (average annual) concentrations, the research will provide valuable information on how to best take and evaluate measurements to estimate long-term, chronic risk for VOCs. The relationship between radon and VOC vapor intrusion in a house affected by both was studied. The radon literature could provide valuable lessons for VOC vapor intrusion if there is a relationship, and radon, being much cheaper to measure than VOCs, could be an important tool in improving the investigation and mitigation of VOC vapor intrusion. The long-term performance of modified sorbent-based measurement techniques for time-integrated measurements of indoor air VOCs was examined. The project investigated distributional changes in VOC and radon concentrations in the indoor air, subslab, and subsurface soil gas from an underground source (groundwater source and/or vadose zone source) adjacent to a residence or small commercial building. The time frame of this study is 2 years in order to evaluate the effects due to seasonal variations on radon and VOC vapor intrusion.