US EPA

1434219 

Journal Article 

Intercomparison between conimetric and gravimetric sampling of respirable dust in uranium mines in Saxony and Thuringia - Results and conclusions in view of retrospective exposure assessment 

Bauer, HD; Dahmann, D; Stoyke, G 

1998 

Yes 

Gefahrstoffe, Reinhaltung der Luft / Air Quality Control
ISSN: 0949-8036
EISSN: 1436-4891 

58 

4 

153-160 

WOS:000073914800005 

In a research project funded by the Hauptverband der
gewerblichen Berufsgenossenschaften the dust concentrations in workplaces of former SDAG Wismut
mines will be estimated retrospectively. The evaluation is to be performed on a gravimetric base.
A large amount of konimetric measurement data for respirable dust is available from the successor
company, the Wismut GmbH, beginning in the year 1960. Until the early eighties konimetry was the
only measurement procedure applied on a routine base for the grouping of work procedures and job
categories respectively. Even until 1990 it was the predominat procedure. Prerequisite for the
recalculation of particle number concentrations into gravimetrical respirable dust concentration
is the availability of a sufficient statistically sound recalculation function between the two
methods. For this purpose a large number of intercomparison experiments between gravimetry and
konimetry were performed in underground workplaces of the Wismut GmbH, steadily increasing the
number of measurement instruments and the frequency of konimetric samples taken during the
measurement intervals in the course of the experiments. Intercomparisons were performed in
different lithologies representative for the conditions of uranium mining and under varying
ventilation velocities in the range between 0.1 and 2.2 m/s. The preparation and treatment of the
konimeter discs before the counting and the counting itself were performed according to the
original standards of the former GDR and the requirements of the SDAG Wismut respectively.
Nonplausible deviations between two identical konimetric measurements within the same experiment
could be recognized and eliminated eventually by use of registrating tyndallometric devices in
parallel. This was only done in proven single cases and thus only 64 of the total of 4300
konimetric data (i. e. 1.5 %) had to be disregarded. This small number of not included singular
data had no consequences for the statistical evaluation. While using all pairs of intercomparison
measurements a non-linear regression curve was found to be the most appropriate fit. The
correlation factor was found to be r = 0.832. For the Thuringian uranium mining district a
special recalculation function could be deviated with a regression factor of r = 0.96. A further
differentiation, for example according to different lithologies, was not possible as the number
of measurement pairs was not sufficient to allow for the deduction of a satisfying specific
recalculation function between particle number concentration and gravimetric concentration.