The period of the last three years brought about alarming news of re-identification of Coal Worker’s Pneumoconiosis (CWP) or ‘black lung” in Australia after reports nearly being absent for over five decades. In South Africa, the CWP statistics are unverifiable, but certainly they have not been eliminated. These events have re-kindled the need for better understanding of dust monitoring, performance of sampling devices and compliance determination. Over the last half century, gravimetric sampling has been the fundamental means for dust exposure monitoring using recognised respirable size-selective standards. In both South Africa and Australia, gravimetric sampling technique in coal mines has been followed since 1988 and 1983 respectively using samplers of original Higgins-Dewell (HD) type designs. With an aspirational mine dust exposure limit of 1.5 mg/m3 after the revision of US dust standard, it is equally important to understand the sampling tools used for exposure monitoring. This paper provides the evaluation results of currently used South African and Australian gravimetric samplers compared against the original UK SIMPEDS ‘true reference’ sampler. The results consistently suggested that the South African and Australian cyclones do not conform to the required BMRC or ISO 1995 curve. The results show that the currently used SA and Australian instruments showed a D50 sampling bias as high as 59% and 47% respectively against the size-selective curve. Similarly, when tested under the controlled laboratory coal dust test conditions, the measured levels by South African, Australian and UK standard SIMPEDS sampler were 8.4 mg/m3, 9.8 m/m3 and 6.7 mg/m3 respectively, aligned with the sampling bias. The differences can in part be attributed to the ‘un-auditable’ inherent design and manufacturing quality, or unverifiable data on the size-selective sampling curve. This finding has significant implications towards exposure data collected over the last 25 years and their subsequent use in the arrival of the dose-response curves. Therefore, it is strongly recommended that the harmonised use of ‘true reference’ SIMPEDS cyclone that meets the ISO (1995) criteria uniformly across the industry would benefit the exposure assessment and compliance determination as practiced in the USA.