Porstendörfer J, Pagelkopf P, Gründel M
Institute of Physical Chemistry, Georg-August-University Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany.
Radiat Prot Dosimetry. 2005;113(3):342-51. doi: 10.1093/rpd/nch465. Epub 2005 Apr 13.
The fraction of the positively charged unattached radon decay products, 218Po and 214Pb in indoor air was determined by model calculations. The results of the calculations were confirmed by measurements in a test chamber (volume: 8 m3). The fraction of both radionuclides depends on the attachment parameter (S(1)) and the neutralisation rate (nu) in room air. The total removal parameter S1 = lambda1 + v + q(f) + X = lambda1 C1f/C0 considers the attachment rate to aerosol particles (X), plate-out rate to room surfaces (q(f)) and the ventilation rate (nu) (lambda1: decay constant of 218Po). The S1-value of room can be determined by measurement of the concentration of the unattached 218Po clusters (C1f) and radon (C0). The neutralisation rate (nu) in environmental air depends mainly on the ion production rate. The influence of the relative humidity in the range 30-95% (temperature: 20 degrees C) is negligible. In addition, equal neutralisation rates for 218Po and 214Pb could be derived. In room air with ion production rates between 5 and 500 nC kg(-1) h(-1) mainly generated by the alpha emitters of radon, thoron and their short-lived decay products, the fractions for positive 218Po clusters vary between 55 and 17% and for 214Pb clusters between 53 and 14%. For a typical average concentration of radon (50 Bq m(-3)) and thoron (10 Bq m(-3)) in homes, 48% of 218Po clusters and 45% of 214Pb clusters are positively charged.
通过模型计算确定了室内空气中带正电的未附着氡衰变产物（218Po和214Pb）的比例。计算结果在一个测试腔室（体积：8立方米）中通过测量得到了证实。这两种放射性核素的比例取决于室内空气中的附着参数（S(1)）和中和率（ν）。总去除参数S1 = λ1 + ν + q(f) + X = λ1 C1f/C0，其中考虑了气溶胶颗粒的附着率（X）、房间表面的沉积率（q(f)）和通风率（ν）（λ1：218Po的衰变常数）。房间的S1值可通过测量未附着的218Po簇（C1f）和氡（C0）的浓度来确定。环境空气中的中和率（ν）主要取决于离子产生率。在30 - 95%（温度：20摄氏度）范围内，相对湿度的影响可忽略不计。此外，218Po和214Pb的中和率相等。在主要由氡、钍射气及其短寿命衰变产物的α发射体产生的离子产生率在5至500 nC kg(-1) h(-1)之间的室内空气中，带正电的218Po簇的比例在55%至17%之间，214Pb簇的比例在53%至14%之间。对于家庭中典型的平均氡浓度（50 Bq m(-3)）和钍射气浓度（10 Bq m(-3)），48%的218Po簇和45%的214Pb簇带正电。
