Radioactive Aerosols - Aerosols: Measurement, Dosimetry, and Health Effects - page 398

0.6

y = 0.099 + 0.28 x
R 2 = 0.16

0.5

0.4

0.3

0.2

0.1

0.0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

The average annual radon decay product concentration,
based on measurements by "individual dosimeter"
(kBq/m 3 )

FIGURE 15.1 Average annual radon decay product concentration, based on measurements by individual
dosimeter (kBq/m 3 ).

assessment have brought results that have led to important conclusions concerning the reliability
and validity of these systems.
The summary of the results of these measurements is presented in Figure 15.1. The irst general
conclusion is that these systems yield inconsistent results. It can be seen from Figure 15.1 that the
correlation coeficient is very low—0.16. Thus, the general question arises as to which system is
more reliable and practicable.
The ratio of annual concentration, that is, mean ASS/mean IDS, varies from 11 to 0.14, depend-
ing on the mine and the year of implementation of the ASS. The results show that the policy of air
sampling is very important, because soon after ASS implementation the effect which the authors
called “hunting for results” takes place, that is, radiation oficers or dosimetrists look for places
where concentration will be higher, or in other words they “hunt” for results, neglecting the strict
instruction given to them during the training courses before implementing ASS. The opposite
effect, revealed by results collected in two other mines, can be called the “avoidance of inconve-
nient results.” The authors suspected that in these cases, the radiation safety oficers probably tried
to hide the results that would increase the mean value, or simply avoid places in which miners work
at relatively higher concentration.
Both the aforementioned effects distort the real picture of both concentrations and miners' expo-
sure. The “hunting” effect appears to be disappearing over the years, but it sometimes turns into the
“avoidance” effect, and the “avoidance” effect appears to be more serious.
The conclusion was drawn that IDS is more reliable in miners' exposure assessment than the cur-
rently implemented ASS. Nevertheless, ASS should not be abandoned, because it is obviously better
than nothing and plays a useful role as a tool for technical preventive actions.
Still, as a measure of real irradiation of the lungs of all miners, these standard types of measure-
ments should be called into question, because the calculation of the activity (dose) to the lungs of
individuals or groups of miners based on the results of such measurements will yield results with
such uncertainty, which is unacceptable in the dose and, correspondingly, the risk assessment.