Many of these possible limitations are difficult to study in the laboratory since they depend on the variety of atmospheric conditions that can be found in different homes. Currently we are also studying the relationship between long-term integrated radon gas exposure and implanted activity in houses in Minnesota and Finland. Other researchers from the Swedish Radiation Institute and University College Dublin are collaborating in these studies. We hope to have all the world's glass-based retrospective reconstruction systems intercalibrated. To assay the radionuclide content and emanation rates, we've measured the natural and man-made gamma emitting radioisotope contents of hundreds of samples of rock, soil, and water from throughout the upper Midwest.
Granites have an undeserved reputation for being a major source of radon in our region.
Currently we are measuring an extensive set of glass samples to determine the range of intrinsic radioactivity in domestic glass. 137 Cs , generated by the testing, began depositing in North America in 1954, reached a peak in 1964, and then stopped. We've had some experience looking. We've found some from both waste generators. These systems should be stable against a variety of environmental attacks including earth quakes and floods.