Harmful airborne particles may be released and inhaled by employees when containers are filled with solid substances. Measurements of the respirable and inhalable particle fractions were therefore taken in ten enterprises when this activity was being carried out. These investigations were intended to assess workers' exposure and the efficacy of different protective measures. The dustiness of all the substances being handled was measured.
The results show it is necessary to distinguish between manual filling using tools (e.g. a hand shovel) and (semi-)automatic filling machines. These tasks have to be considered and assessed separately when risk assessments are carried out. Personal air sampling of both particle fractions during specific activities provided more informative data than stationary sampling. Generally, personal air sampling is therefore to be preferred.
The strongest correlation between the concentrations of the respirable and inhalable particle fractions was found using a power function. This should be kept in mind in future when converting measurement results or deriving limit values. This correlation was noticeably stronger for stationary devices than manual filling, for which exposure was determined to a greater extent by workers´ individual behaviour.
The results of the investigation are presented in video clips that compare different techniques with superimposed graphics of the signals from direct-reading instruments to demonstrate the efficacy of the protective measures that were taken.
The correlation between the airborne particle concentration and dustiness was much stronger for the inhalable particle fraction than for the respirable particle fraction. This indicates that, as a measurable characteristic, dustiness can be drawn on to categorise solid substances’ potential to release inhalable particles when assessments are conducted on the basis of the “Easy-to-use Workplace Control Scheme for Hazardous Substances” (EMKG).
There is a need for continued investigation of the correlation between the dustiness values of both particle fractions, which is found as an exponential function. Further measurements and considerably larger data sets are required in order to clarify this assumed relationship.
Unit 4.4 "Measurement of Hazardous Substances"
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