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TESTING OF INDOOR RADON REDUCTION TECHNIQUES IN 19 MARYLAND HOUSES
Citation:
Gilroy, D. AND W. Kaschak. TESTING OF INDOOR RADON REDUCTION TECHNIQUES IN 19 MARYLAND HOUSES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/8-90/056 (NTIS PB90-244393), 1990.
Impact/Purpose:
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Description:
The report gives results of testing of indoor radon reduction techniques in 19 existing houses in Maryland. The focus was on passive measures: various passive soil depressurization methods, where natural wind and temperature effects are utilized to develop suction in the system; and sealing of radon entry routes into the house. Active (fan-assisted) soil depressurization techniques were also tested. Passive soil depressurization systems typically gave moderate radon reductions (30-70%), although the reductions ranged from zero to 90%. Only two houses were reduced 4 pCi/L with the passive systems. A passive system is most likely to be successful when sub-slab communication is very good, when the house has a basement with no adjoining slab-on-grade or crawl-space wings, and when the foundation walls are poured concrete instead of hollow block. Entry route sealing as a stand-alone radon mitigation measure gave zero-50% reduction in the only house where it was tested. Active soil depressurization, tested in 18 houses, reduced 16 of them 4 pCi/L, and 12 of them 2 pCi/L; reductions were often > 90%. Poor sub-slab communication prevented this approach from being fully successful in the other two houses; later modifications to these two systems reduced these houses 4 pci/L also.