Indoor activity size distribution of the short-lived radon progeny
Indoor activity size distribution of the short-lived radon progeny
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DOI：
10.1007/s00477-015-1057-x
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发表时间：
2015
影响因子：
4.2
通讯作者：
M. Yuness;A. Mohamed;Hyam Nazmy;M. Moustafa;M. El-Hady
中科院分区：
文献类型：
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作者：
M. Yuness;A. Mohamed;Hyam Nazmy;M. Moustafa;M. El-Hady
连续几周测量了室内空气中短寿命氡子体的活度分布。使用了两种不同的测量技术：低压伯纳级联冲击器直接测量~(214)Pb和~(214)Bi的附着分数(≥100 nm)和基于丝网扩散电池测量的间接测量(未附着分数0.5~5 nm，218Po，214Pb)。同时，记录了温度、湿度等气象参数。测得的氡子体活度分布可以用三种对数正态分布模式(成核、积累和粗略)的总和来近似。最大的活度组分吸附在气溶胶颗粒上，其活度中位数空气动力学直径(AMADA)和几何标准偏差(GSDA)值分别为250-500 nm和1.5-3.5。气象条件对累积颗粒物活性的影响不显著。与测量结果相反，一小部分但相当大的氡子体(平均值为5%)附着在粗颗粒(>；1000纳米)上。这一比例在0到10%之间变化。另一方面，虽然独立活动的量不超过总活度的10%，但被认为产生的辐射剂量约为总辐射剂量的50%。测得~(218)Po和~(214)Pb的平均热力学当量直径分别为1.28和1.30 nm，相对平均几何标准偏差分别为1.30和1.24。根据所获得的氡子体大小分布(附着体和非附着体)的结果，利用肺沉积模型估算了人肺的总沉积分数。
Activity size distribution of the short-lived radon progeny in indoor air was measured continuously over several weeks. Two different measurement techniques were used: a direct measurement with a low-pressure Berner cascade impactor for attached fraction of214Pb and214Bi (≥100 nm) and an indirect determination based on measurement with a wire screen diffusion battery (unattached fraction 0.5–5 nm,218Po,214Pb). In parallel, the meteorological parameters like temperature, humidity were registered. Measured activity size distribution of radon progeny can be approximated by a sum of three log-normal distributions modes (nucleation, accumulation and coarse). The greatest activity fraction was adsorbed on aerosol particles in the accumulation size range (100–1000 nm) with activity median aerodynamic diameters (AMADa) and geometric standard deviations (GSDa) values of 250–500 nm, and 1.5–3.5, respectively. The influence of the weather conditions on the activity of the accumulation particles was not significant. In contrast to the results of measurements a small but significant fraction of the radon progeny (average value 5 %) was attached to coarse particles (>1000 nm). This fraction varied between 0 and 10 %. On the other hand, although the amount of unattached activities not more 10 % of the total activity, but is considered to yield about 50 % of the total radiation dose. The mean thermodynamic equivalent diameters of218Po and214Pb were determined to be 1.28 and 1.30 nm with relative mean geometric standard deviations of 1.30 and 1.24, respectively. Based on the obtained results of radon progeny size distributions (attached and unattached), the total deposition fractions of the human lung were evaluated by using a lung deposition model.