Mayya Y S, Prasad S K, Nambiar P P, Kotrappa P, Somasundaram S
Health Phys. 1986 Dec;51(6):737-44. doi: 10.1097/00004032-198612000-00004.
The concentration of 220Rn in the exhaled breath of workers currently employed in a Th plant was measured using a double filter system. The results are expressed in terms of the equivalent activity of 224Ra freely emanating 220Rn at the mouth. Measurements performed on 176 subjects, without isolating them from day-to-day work, showed 220Rn levels having a median of 0.74 Bq, with the group consisting of sweepers and helpers showing the highest average level (1.68 Bq). Measurements performed on 15 selected workers, after isolating them from work for a minimum duration of 48 h yielded 220Rn levels which were consistently lower than those obtained in the first measurements. This is attributed to the material undergoing short term elimination from the body. It was also found from the latter measurements that the group consisting of workers engaged in radioactive work for more than 24 y has an average 220Rn level of 2.65 Bq which is significantly higher than that (1.27 Bq) found in the group that has worked for less than 12 y. A conversion factor of 0.09 deduced by earlier investigators is assumed to be valid for estimating the actual 224Ra burdens from the 220Rn data.
采用双滤器系统测量了钍厂在职工人呼出气体中220Rn的浓度。结果以口腔中自由释放220Rn的224Ra等效活度表示。对176名受试者进行的测量（未将他们与日常工作隔离）显示，220Rn水平中位数为0.74 Bq，其中清扫工和助手组的平均水平最高（1.68 Bq）。对15名选定工人进行测量（将他们与工作隔离至少48小时后）得到的220Rn水平始终低于首次测量结果。这归因于该物质从体内的短期消除。从后一次测量中还发现，从事放射性工作超过24年的工人组的平均220Rn水平为2.65 Bq，显著高于工作年限少于12年的组（1.27 Bq）。假定早期研究人员推导的0.09的转换因子对于根据220Rn数据估算实际224Ra负荷是有效的。
