RADON RISK MAPPING USING HIGH RESOLUTION GAMMA SPECTROMETRY AND SOCIAL VULNERABILITY INDICES IN NORTHEASTERN NORTH CAROLINA

Radon (²²²Rn) is a colorless, odorless, inert radioactive gas that emits alpha radiation, making radon inhalation the leading cause of lung cancer among non-smokers worldwide. Previously published radon hazard maps for the United States are low-resolution and rely on coarse geologic maps, aerial radioactivity, soils, and typical home foundation types. Based on these data, the Mid-Atlantic Coastal Plain is broadly generalized as low radon risk, yet indoor radon tests in the coastal plain of North Carolina show measurements as high as 54 pCi/L, approximately 18 times the U.S. Environmental Protection Agency’s action level. Here we combine uranium-series radionuclide measurements from sediment cores with social vulnerability data to create higher resolution radon hazard maps. Using ultra low background high resolution gamma spectrometry, we measure ²³⁸U, ²²⁶Ra, and ²¹⁰Pb in sediment cores within Nash and Edgecombe Counties in the North Carolina Coastal Plain. Because radon gas exposure does not impact all populations equally, we propose to include social vulnerability data alongside geological and geochemical data in radon hazard mapping.

Radon disproportionately affects socially vulnerable and historically excluded populations, such as military veterans, LGBTQ adults, low-income households, indigenous peoples, and those with mental or behavioral health conditions. Thus, the effects of radon gas cannot be generalized across a county’s population. We overlay demographic data relating to the themes of socioeconomic status, household composition/disability, and race/ethnicity/language from the Center for Disease Control’s Social Vulnerability Index (SVI) with measured values of ²²⁶Ra in core sections. In addition to high indoor radon levels, our study area shows a high vulnerability with regards to these three SVI themes. Preliminary measurements indicate that ²²⁶Ra varies widely within a single core, from 8.41 to 71.1 Bq/kg, and we will study the factors controlling this variability. Our results support the need for further mapping efforts in the North Carolina Coastal Plain to encourage radon mitigation and public health efforts within an area previously deemed low risk.