Department of Radiation Measurement and Physical Dosimetry, Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan; Department of Radiation Science, Graduate School of Health Sciences, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan; Center for Environmental Remote Sensing, Chiba University, 1-33 Yayoi-cho, Inage, Chiba, 263-8522, Japan.
National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, 2 Xinkang Street, Dewai, Beijing, 100088, China.
J Environ Radioact. 2022 Apr;244-245:106830. doi: 10.1016/j.jenvrad.2022.106830. Epub 2022 Feb 3.
Radiation exposure due to radon contributes most of the ionizing radiation exposure to people among natural radiation sources. This research measured the Rn, Rn by the RADUET and their progeny concentrations by the improved deposition based Rn and Rn progeny monitor, and the contribution of outdoor PM concentrations to indoors by a modified steady-state mass balance model in Beijing, Changchun, China and Aomori, Japan. Based on these results, we preliminarily explored the relevance between the city level outdoor PM exposure and indoor Rn, Rn inhalation exposure in these three metropolises with different air quality levels. The average equilibrium equivalent radon concentration (EERC) and equilibirum equivalent thoron concentration (EETC) indoor were 17.2 and 1.1 Bq m in Beijing, 19.4 and 1.3 Bq m in Changchun, and 10.8 and 0.9 Bq m in Aomori, respectively. The indoor EERC and EETC in Beijing showed 1.4 and 2.2 times as high as that measured in 2006. The indoor radiation dose due to inhalation presented in a descending order as Changchun, Beijing and Aomori, which were in accordance with their outdoor Rn concentrations. The indoor radiation doses due to Rn contributed 30% of the total dose in the three cities, indicating that Rn cannot be neglected when evaluating indoor radiation dose. It should be noted that, the indoor PM concentrations of outdoor origin presented strong correlation (r = 0.772) with indoor EETC and moderate correlation (r = 0.663) with indoor EERC, indicating that the PM of outdoor origin can break the concentration balance of the indoor PM, then affect the indoor Rn and Rn behaviors, and further affect the inhalation exposure of radon.
氡辐射暴露是人们在自然辐射源中所受电离辐射暴露的主要来源。本研究采用 RADUET 测量氡浓度及其子体浓度，采用改进的基于沉积的氡和氡子体监测仪测量氡及其子体浓度，并采用改进的稳态质量平衡模型测量室外 PM 浓度对中国北京、长春和日本青森室内的贡献。在此基础上，我们初步探讨了这三个城市不同空气质量水平下，城市层面的室外 PM 暴露与室内氡、氡吸入暴露之间的相关性。北京、长春和青森室内的平均平衡等效氡浓度（EERC）和平衡等效钍浓度（EETC）分别为 17.2 和 1.1 Bq m、19.4 和 1.3 Bq m、10.8 和 0.9 Bq m。北京室内 EERC 和 EETC 比 2006 年测量值高 1.4 倍和 2.2 倍。室内吸入辐射剂量呈长春、北京、青森依次降低的趋势，这与它们的室外氡浓度一致。室内氡所致辐射剂量占总剂量的 30%，表明在评估室内辐射剂量时不能忽视氡。需要注意的是，室外来源的室内 PM 浓度与室内 EETC 呈强相关（r = 0.772），与室内 EERC 呈中度相关（r = 0.663），表明室外来源的 PM 可以打破室内 PM 的浓度平衡，从而影响室内氡及其子体的行为，进而影响氡的吸入暴露。
