Abstract |
The report gives results of an EPA radon mitigation demonstration project involving 14 houses in the Nashville, TN, area with indoor radon levels of 5.6-47.6 pCi/L, using a variety of techniques, designed to be the most cost effective methods possible to implement, and yet adequately reduce radon levels to < 4 pCi/L. For crawl space houses, the techniques included sealing openings between living areas and crawl spaces and then passively venting the crawl spaces, depressurizing the crawl spaces, depressurizing under polyethylene sheeting in the crawl spaces, and depressurizing the crawl space soil itself. For basement and basement/crawl space combination houses, the techniques included sub-slab pressurization and depressurization, block wall depressurization, and combinations of these techniques with some of those listed above for exposed soil areas. Post-mitigation worst-case radon levels in these houses were generally from < 1 to about 5 pCi/L, with one house near 15 pCi/L. These houses are currently being followed with alpha-track detectors to assess the long term exposure levels. |