Ivanova Kremena, Stojanovska Zdenka
National Centre of Radiobiology and Radiation Protection, 3 Sv. Georgi Sofiyski St., 1606, Sofia, Bulgaria.
Faculty of Medical Sciences, Goce Delcev University of Stip, 10-A Krste Misirkov st, 2000, Stip, Republic of Macedonia.
Radiat Environ Biophys. 2019 Aug;58(3):337-344. doi: 10.1007/s00411-019-00789-y. Epub 2019 Apr 6.
In this study, temporal variations of indoor radon concentrations in Bulgaria were investigated. The radon concentrations were measured by nuclear track detectors as part of the Bulgarian National Survey, performed in the dwellings of 28 regional districts. The detectors were exposed through a year in two consecutive time periods of different lengths. For 2433 dwellings, measurements could be completed for both time periods, while for 345 dwellings they could only be completed for one of the periods. To estimate any missing radon concentrations, a temporal correction procedure was developed. This procedure, which included development of a linear correlation between the ln-transformed radon concentrations from the 9-month period [CRn(L)] and from the 3-month period [CRn(S)]. A normal distribution of the data, which is a condition for linear regression, was achieved when the ln-transformed radon concentrations were grouped by climate zone, then by regional districts, and finally by the presence/absence of a basement in the investigated building. The linear models obtained for each group showed reasonable coefficients of determination (R ≈ 0.50) and root mean square errors (RMSEs) of about 0.50. When these correlations were used to reconstruct radon concentrations in missing measurement periods, it turned out that the reconstructed data (for 345 dwellings) were within the 95% confidence interval of the measured data (for 2433 dwellings). The geometric means of CRn(L) and CRn(S) were 76 Bq/m and 100 Bq/m, respectively, for 2433 dwellings, which are almost equal to those of 75 Bq/m and 98 Bq/m, which represent the measured and reconstructed data together (for 2778 dwellings).
在本研究中，对保加利亚室内氡浓度的时间变化进行了调查。作为保加利亚国家调查的一部分，使用核径迹探测器在28个地区的住宅中测量了氡浓度。探测器在一年中连续两个不同长度的时间段内暴露。对于2433户住宅，两个时间段的测量都可以完成，而对于345户住宅，只能完成其中一个时间段的测量。为了估计任何缺失的氡浓度，开发了一种时间校正程序。该程序包括建立9个月时间段[CRn(L)]和3个月时间段[CRn(S)]的对数转换后的氡浓度之间的线性相关性。当按气候区、然后按地区、最后按被调查建筑物是否有地下室对对数转换后的氡浓度进行分组时，数据实现了正态分布，这是线性回归的一个条件。为每个组获得的线性模型显示出合理的决定系数（R≈0.50）和均方根误差（RMSE）约为0.50。当使用这些相关性来重建缺失测量时间段内的氡浓度时，结果表明重建数据（345户住宅）在测量数据（2433户住宅）的95%置信区间内。对于2433户住宅，CRn(L)和CRn(S)的几何平均值分别为76 Bq/m和100 Bq/m，这与代表测量和重建数据总和（2778户住宅）的75 Bq/m和98 Bq/m几乎相等。
