Venoso G, Ampollini M, Antignani S, Carpentieri C, Bochicchio F
Istituto Superiore di Sanità (Italian National Institute of Health), National Centre for Radiation Protection and Computational Physics, Viale Regina Elena 299, 00161 Rome, Italy.
J Radiol Prot. 2016 Dec;36(4):922-933. doi: 10.1088/0952-4746/36/4/922. Epub 2016 Nov 28.
Measurements covering a 1 year period are often used and required by legislation to assess the average radon concentration within a house or a workplace. This kind of long-term measurement-generally carried out with techniques based on nuclear track detectors-can be affected by a reduction in sensitivity due to ageing and fading of latent tracks during the exposure period, thus resulting in an underestimation of the actual average concentration. In order to evaluate in field conditions the ageing and fading effects on annual radon concentration measurements, two different studies in a large sample of rooms in dwellings (162) and in workplaces (432) were conducted using two different techniques (detector and track read-out system): (i) CR-39 plastics readout with a fully automated image analysis system, and (ii) LR 115 films with a spark-counter for track counting. Study design and data analysis aimed to evaluate both the average and the variability of ageing and fading effects in real conditions, and to reduce and separate the contribution of measurement uncertainty to the observed variability. For the CR-39 based technique, the results show that radon concentration measurements over a 12month period are on average about 16% lower than those evaluated with measurements of two consecutive 6 month periods, implying the need for a correction factor to avoid measurement bias (i.e. underestimation) due to ageing and fading effects. The observed variability of ageing and fading effects among the sampled rooms is not negligible (coefficient of variation about 18%), although a considerable fraction is attributable to measurement uncertainty, which is presumably not related to ageing and fading. For the technique based on LR 115 spark counting, ageing and fading do not significantly affect the results of radon concentration measurement.
立法通常要求采用涵盖1年时间段的测量数据来评估房屋或工作场所内的平均氡浓度。这种长期测量——通常采用基于核径迹探测器的技术进行——可能会受到以下因素影响：在暴露期间，潜径迹会因老化和褪色而导致灵敏度降低，从而造成对实际平均浓度的低估。为了在实地条件下评估老化和褪色对年度氡浓度测量的影响，利用两种不同技术（探测器和径迹读出系统），在大量住宅房间样本（162个）和工作场所样本（432个）中开展了两项不同的研究：（i）使用全自动图像分析系统读取CR - 39塑料探测器数据，以及（ii）使用火花计数器对LR 115薄膜进行径迹计数。研究设计和数据分析旨在评估实际条件下老化和褪色效应的平均值及变异性，并减少和区分测量不确定度对观测到的变异性的贡献。对于基于CR - 39的技术，结果表明，12个月期间的氡浓度测量平均值比连续两个6个月期间测量所评估的值平均低约16%，这意味着需要一个校正因子来避免由于老化和褪色效应导致的测量偏差（即低估）。在采样房间中观察到的老化和褪色效应的变异性不可忽略（变异系数约为18%），尽管相当一部分可归因于测量不确定度，而这大概与老化和褪色无关。对于基于LR 115火花计数的技术，老化和褪色对氡浓度测量结果没有显著影响。
