Conventional coal characterisation such as proximate and ultimate analysis as well as determination of sulphur forms in coal samples were carried out following the ASTM and ISO standards. Key characteristics of coal samples from the supply stock to the newly commissioned South African National Power Utility's (Eskom's) Medupi Power Station - which receives its supply coal from the Waterberg coalfield in Lephalale (Limpopo Province, South Africa) - were evaluated. Makgato, Stanford S Chirwa, Evans M Nkhalambayausi Waterberg coal characteristics and SO2 minimum emissions standards in South African power plants. CDE contributed to a statistically significant 0.19% and 0.11% greater decline in the percent predicted 1-second forced expiration volume (FEV1) and forced vital capacity (FVC), respectively, among current miners with pneumoconiosis than among those without. A significant (P<0.0001) additional 58 mg-years/m3 CDE was seen among those with pneumoconiosis compared to those without. A significant association (P<0.001) and trend (P<0.001) was seen for pneumoconiosis with increasing categories of CDE among current miners only. The degree of agreement between the two readers for profusion was moderate to high (kappa=0.58).
The overall prevalence of pneumoconiosis was low (2%-4%). Because of possible confounding by employment status, most analyses were stratified on current and ex-miner status. An average profusion score was used in the analysis for the outcomes of interest. kappa-Statistics compared the radiographic outcomes predicted by the two readers. Cumulative respirable dust exposure (CDE) estimates were constructed from historical company-collected sampling and researcher-collected personal dust measurements. Spirometry was performed by trained technicians. Interviews were conducted to assess symptoms, work histories (also obtained from company records), smoking, and other risk factors. Chest radiographs were read according to the International Labour Organization (ILO) classification by two experienced readers, one an accredited National Institute for Occupational Safety and Health (NIOSH) "B" reader.
A total of 684 current miners and 188 ex-miners from three bituminous- coal mines in Mpumalanga, South Africa, was studied. This study, the first to document the prevalence of pneumoconiosis among a living South African coal mining cohort, describes dose-response relationships between coal workers' pneumoconiosis and respirable dust exposure, and relationships between pneumoconiosis and both lung function deterioration and respiratory symptoms. Naidoo, Rajen N Robins, Thomas G Solomon, A White, Neil Franzblau, Alfred Radiographic outcomes among South African coal miners.
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