Document Type

Conference Paper

Publication Date


Publication Details

B. Belle, Experiences of the institute of occupational medicine foam respirable sampler use in mines, 12th Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 2012, 202-211.


The mining industry worldwide spends a significant amount of human and financial resources in sampling of safety and health hazards for ensuring adequate control measures. Most mining countries carry out personal exposure monitoring for respirable dust. Unlike Australia, very few countries spend their resources in sampling of inhalable dust in mining industry. Over the years, size-selective sampling curve and instruments which replicate human inhalation have also changed. In addition, since its inception in 1920s, the recommended occupational exposure limits of a substance have varied significantly between mining countries worldwide. This paper discusses the experiences of introducing newly available monitoring instruments through laboratory and field evaluation. The institute of occupational medicine respirable foam sampler was evaluated in coal, diamond, gold and platinum mines. For comparison purposes, Higgins-Dewell type cyclone that conforms to the new size-selective curve with a D50 of four microns was used as a “true” reference sampler. For the laboratory study, the two samplers were exposed to two types of dust, viz. coal and sandstone briquette dust with a quartz content of 50.6%. Based on the results of the laboratory study, the correlation coefficient (r) between the foam and reference sampler was found to be 0.79 and 40% underestimation in measured values by the foam foam sampler (p-value of 0.000). Field evaluations of side-by-side foam and reference samplers in coal, gold, platinum and diamond mines, showed a poor non-linear relationship (r = 0.67) for a wide range of dust levels. From the non-linear regression equation, on average, the foam respirable sampler underestimated the dust levels by approximately 48% for a compliance level of 2 mg/m3. For increased dust levels, the underestimation of the measured dust levels by the foam sampler also increased, which led to the sampler being unsuitable for use during engineering control purposes. In overall, the foam sampler failed to meet the NIOSH accuracy criteria and was not pursued further for use in South African mines. Study suggests sufficient and prior due-diligence of any new instruments or methodologies to industry wide applications. Any modifications to sampling methodology or introduction of new instruments must ensure that the collected exposure data is relevant for continued development of long term dose-response curves and understand potential level of risks.