Radon and geology
Residential radon concerns came onto most Americans ’ radar in the 1980s , when engineer Stanley Watras set off radiation detectors while entering the Limerick nuclear power plant in Pottstown , Pennsylvania , — before it had any radioactive material onsite . State and federal officials subsequently found the average radon level at Watras ’ house to be 2,500 picocuries per liter .
Colorless , tasteless and odorless , radon is produced by the decay of uranium , which is found in varying amounts throughout the earth ’ s crust .
Scientists have long known that radon concentrations are connected with geology .
“ Because of the known presence of uranium-bearing materials in some of the rocks that compose the Piedmont and Blue Ridge , these provinces are more ‘ suspect ’ than the Coastal Plain , the Valley and Ridge , and the Appalachian Plateaus ,” wrote a task force convened by Virginia ’ s secretary of human resources in 1988 to study the risks of residential radon .
Thirty years later , a study by the Office of Radiological Health on whether radon testing and mitigation professionals should be licensed added a caveat : “ It should be understood that areas in Tidewater , not to mention the commonwealth at large , have pockets of elevated radon levels due to the existence of mineable-quality uranium .”
While not linked to mining , Berquist and Kaste found such a pocket throughout the fossil-heavy Yorktown Formation , whose high concentrations of uranium appear to be linked to the high levels of radon detected in homes built above or into it . The researchers have since developed an interactive radon risk assessment map for the Williamsburg area .
“ We want to know how the uranium got in there ,” said Berquist . Multiple theories related to fossil composition , geologic events and ground and water chemistry are possible , he added . “ I don ’ t know the exact mechanism .”
Radon risks in homes
How radon gets into houses is clearer : Because it is a gas , it is capable of moving through rock fractures and soil and therefore can seep inside houses , where it can get trapped .