These detectors use the implanted 210 Po activity in glass and the deposited 218,214 Po activity to reconstruct past radon concentrations and radon-related dose. The analysis of the risk of lung cancer from the radon progeny exposure reconstructed from RRDs is underway. Most of these homes were first measured in the mid 1980's. This project is scheduled to run until 2000. Some houses show a systematic change in radon.
Some houses show a dramatic change when they are renovated.
We're studying possible correlation with climatic changes. We used ATD detectors in Minnesota and Iowa to measure, and map, outdoor radon concentrations. We had about one measurement in every county in Iowa. In Minnesota, we studied more localized variability and found it to be small. We found that there were sections in the western part of both states where the outdoor radon concentration was higher than it is indoors in most places in the world. .