An analysis of the impact of geology on indoor air radon concentration

Radon ( 222 Rn 86 ), a radioactive gas formed by the decay of uranium and radium in rocks and minerals, can seep into houses, accumulating in the indoor air. Breathing radon-rich indoor air is the leading cause of lung cancer, after smoking, resulting in around 21,000 deaths in the US each year. The US Surgeon General advises taking action at 4 pCi/L or higher. Approximately 1 in 15 homes could have an indoor air radon concentration at or above 4 pCi/L. In this study, 134,496 indoor air radon test results from the state of Georgia, USA were analyzed. The tests were conducted between 1990 and 2022. The test results were analyzed in relation to the five well-recognized physiographic provinces in the state with contrasting underground geological features. Significantly different mean/median/mode and spread of radon concentration, frequency of high radon, and potential lung cancer risk were evident for different physiographic provinces. The highest indoor air radon levels and the highest lung cancer risk in Georgia were associated with the underground metamorphic rocks Gneiss-Schist-Quartzite, followed by Granite, Limestone-Dolomite-Shale, and Limestone-Sandstone-Shale. The lowest radon and lung cancer risks were associated with the unconsolidated marine sediments, but the risk was still significant. These findings help to substantiate the need for supporting policies and education related to increasing radon testing, mitigation, and regulations, especially in states with similar geological features. Population density, diversity, rurality, and health-literacy in various physiographic provinces should be considered together with these findings to properly realize the risk of radon from a public health standpoint. • Georgia’s Blue Ridge and Piedmont regions contain Uranium-rich rocks and minerals. • Homes on Gneiss-Schist-Quartzite and Granite rocks had higher indoor radon levels. • Radon levels and lung cancer risk were different in the 5 physiographic provinces. • Radon levels and lung cancer risk were related to underground geological features. • Both radon levels and lung cancer risk followed the order of CP<APP<VR< P < BR.