Table_1_A large and feasible national survey representative of population exposure to outdoor gamma radiation in urban areas.XLSX

BackgroundAlthough data on outdoor gamma radiation are available for many countries, they have generally been obtained with measurements performed in undisturbed environments instead of in urban areas where most of the population lives. Only one large national survey, with on-site measurements in urban areas, has been identified worldwide, probably due to high costs (e.g., personnel and instrumentation) and difficulties in selecting measuring points.
MethodsA campaign of outdoor gamma radiation measurements has been carried out in the entire Italian territory. All measurement points were selected at the infrastructures of an Italian telecommunications company as representatives of all the possible situations of outdoor exposure to gamma radiation for population in urban areas. Ten replicates of portable gamma (X) detectors carried out all the measurements.
ResultsApproximately 4,000 measurements have been performed. They are distributed across 2,901 Italian municipalities, accounting for 75% of the Italian population. The national population-weighted mean of the gamma ambient dose equivalent rate (ADER) is 117 nSv h−1, and it ranges from 62 to 208 nSv h−1 and from 40 to 227 nSv h−1 for 21 regions and 107 provinces, respectively. The average variability at the municipal level, in terms of the coefficient of variation (CV) is 21%, ranging from 3 to 84%. The impact of land coverage and the distance from a building on the outdoor gamma radiation level was assessed with complementary measurements, leading to differences ranging from −40 to 50% and to 50%, respectively.
ConclusionA representative campaign of outdoor gamma dose rate measurements has been performed in Italy, only in urban areas, to assess the exposure effect due to outdoor gamma radiation on the population. It is the largest national campaign in urban areas worldwide, with a total of 3,876 on-site measurements. The land coverage and the distance from surrounding buildings were recognized to strongly affect outdoor gamma radiation levels, leading to high variability within small areas. The collaboration with a company that owns a network of facilities on a national territory as dense as the residing population made this survey feasible and affordable. Other countries might adopt this methodology to conduct national surveys in urban environments.

研究背景：尽管许多国家已拥有室外伽马辐射（gamma radiation）相关数据，但这些数据大多采集自未受干扰的自然环境，而非多数人口聚居的城市区域。目前全球范围内仅发现一项针对城市区域开展现场测量的大型全国性调查，这可能源于高昂的成本（如人员与仪器设备投入）以及测点选取的重重困难。

研究方法：本研究在意大利全境开展了室外伽马辐射测量调研项目。所有测点均选取自某意大利电信公司的基础设施点位，以代表城市区域人群可能面临的各类室外伽马辐射暴露场景。本次测量全部采用便携式伽马（X）探测器完成，共开展10组重复测量。

研究结果：本次调研共完成约4000次测量，覆盖意大利2901个市镇，覆盖人口占意大利总人口的75%。全国人口加权的伽马环境剂量当量率（gamma ambient dose equivalent rate，ADER）平均值为117 nSv·h⁻¹，在21个大区与107个省中的取值范围分别为62~208 nSv·h⁻¹与40~227 nSv·h⁻¹。市镇级别的平均变异程度以变异系数（coefficient of variation，CV）计为21%，取值区间为3%~84%。本研究通过补充测量评估了土地覆盖类型以及与建筑物的距离对室外伽马辐射水平的影响，二者分别导致的辐射水平差异幅度为-40%~50%与50%。

研究结论：本研究仅针对意大利城市区域开展了具有代表性的室外伽马剂量率测量调研，以评估人群所受室外伽马辐射的暴露影响。本次调研共计完成3876次现场测量，是目前全球范围内规模最大的城市区域全国性伽马辐射测量项目。研究证实，土地覆盖类型以及与周边建筑物的距离会对室外伽马辐射水平产生显著影响，进而导致小区域内出现较高的辐射水平变异。本研究通过与一家在全国范围内布设了密度与居住人口相当的设施网络的企业开展合作，使得本次调查兼具可行性与经济性。其他国家可借鉴本次研究方法，在本国城市环境中开展全国性辐射调查。