Radioactive Aerosols - Aerosols: Measurement, Dosimetry, and Health Effects - page 397

6. For deposited activity in lungs, the combination of breathing rate and deposition coeficient
is important, and not these values separately.
A new value, FAL, was introduced as a combination of breathing rate v and deposition
coeficient k (FAL = vk ) as a bridge between concentration in the breathing zone and activ-
ity in the lungs. FAL can be estimated by measurement of the gamma-activity in the lungs
of miners and radon progeny concentration in the breathing zone. This method permits
measurements on miners without disturbing their real working conditions (noninvasion
approach) and was used for the measurement of different groups of miners. The error in
estimating FAL was 20%, which is many times smaller than the combined error in the
assessment of breathing rate and deposition coeficient (Urusov, 1972; Alterman, 1974;
Ruzer et al., 1995).
7. In Ruzer (1958, 1964) and Ruzer and Urusov (1969), the method of direct measurement of
the activity in the lungs of miners was developed and used in miner measurements both for
the assessment of activity in the lung and for the estimation of deposition of radon decay
products. The accuracy of activity assessment in the lungs of miners, including corrections
on the shift equilibrium in the air and geometric factors, was 30%-40%.
No correlation was found between direct measured activity in the lungs of miners and calculated
activity based on radon progeny concentrations measured by the standard procedure. On the other
hand, a relationship was found between the concentration in the breathing zone, the parameter of
physical activity (FAL), and direct measured activity in the lungs.
As a result of this, conclusions should be made that the total uncertainty of the activity in the
lungs or the dose for miners calculated on concentration measurements can be on the order of hun-
dreds of percent. But because errors close to even 100% make no sense, it is better to express this
uncertainty in such a way that the true value of the dose or the activity in the lung can be at least on
the order of magnitude lower or higher than calculated.
Only direct measurements of activity can produce an accuracy acceptable from the dosimetric
point of view and close to the statistical error that is used in the assessment of lung cancer mortality.
In Domanski et al. (1989), the results of a long-term study were described by comparing two
independent systems, that is, the ASS and the IDS, which were implemented and tested for 6 years
simultaneously in Polish underground metal-ore mines.
Each of these systems has certain different inherent advantages and critical weak points. The
main feature of the ASS is usually the relatively high precision of each single measurement; how-
ever, the strategy of monitoring and the selection of the proper frequency of monitoring and the site
of the system on the area of the mine still remains the weak point of the ASS.
On the other hand, the critical point of the IDS lies in the cost of the measuring devices or in
the doubtful precision of the measurement technique. The term “dosimetry system” should also not
be used, because such types of instruments measure only concentration, not the dose, which in this
case depends on physical activity.
The ASS system was implemented in all Polish underground copper and zinc—lead ore mines
between 1981 and 1983, and the crucial point, that is, strategy of monitoring and sampling, was
thoroughly considered, discussed, and inally approved by the Institute of Occupational Medicine.
It was recommended that from tens to several hundreds of potential alpha-energy concentration
measurements of radon progeny in the year would be done at the sites where miners actually work
and in the local air stream outlets.
The IDS, based on “individual dosimeters” worn by miners on the backs of their helmets, was
introduced in all the mines under consideration in the period between 1977 and 1979. This system
is based on the use of small cassettes containing a track etch detector foil sensitive to alpha-particles
emitted by radon decay products.
Thousands of measurements conducted simultaneously in 11 metal-ore mines under these
two technically compatible, but entirely independent, long-term systems of radiation exposure