Norwegian Radiation and Nuclear Safety Authority, 0213 Skøyen, Norway.
Centre for Environmental Radioactivity (CERAD CoE), NO-1432 Ås, Norway.
Radiat Res. 2019 Aug;192(4):431-439. doi: 10.1667/RR15403.1. Epub 2019 Aug 7.
Radon (Rn) and thoron (Rn), and especially their short-lived decay products, are major contributors to dose received by the public from naturally occurring radioactive material (NORM), particularly in areas with elevated levels of naturally occurring radionuclides. Mining in such areas can involve ventilation of high amounts of these gases, which may influence outdoor levels. In this work, we assessed indoor and outdoor levels of Rn, Rn and Rn decay products (TnDP) in close proximity to an area with elevated bedrock levels of thorium (Th) and a NORM legacy mining site with high natural ventilation. We assess municipal buildings at distances from a few hundred meters to 2 km from the NORM legacy mines. In some buildings, high indoor levels of Rn were observed in winter, as expected for temperate areas. In summer, high indoor levels of Rn and Rn were observed in some buildings, and very low associated levels of TnDP in actively ventilated buildings may suggest entry by ventilation and an outdoor source. Outdoor levels of TnDP increased with decreased distance from the legacy mines, suggesting dispersal from these during both summer and winter.
氡（Rn）和钍射气（Rn），特别是它们的短寿命衰变产物，是公众从天然放射性物质（NORM）中接受剂量的主要贡献者，特别是在自然放射性核素水平升高的地区。在这些地区进行采矿可能涉及大量这些气体的通风，这可能会影响室外水平。在这项工作中，我们评估了紧邻钍（Th）基岩水平升高地区和具有高自然通风的 NORM 遗留矿区的近区室内和室外的Rn、Rn 和 Rn 衰变产物（TnDP）水平。我们评估了距离 NORM 遗留矿几百米到 2 公里的市政建筑。在一些建筑物中，冬季观察到 Rn 的室内水平很高，这是温带地区的预期情况。在夏季，一些建筑物中观察到 Rn 和 Rn 的室内水平很高，而在通风活跃的建筑物中，非常低的相关 TnDP 水平可能表明通过通风和室外源进入。室外 TnDP 水平随着与遗留矿的距离减小而增加，表明在夏季和冬季都从这些矿中散发出来。
