THE DIMENSIONS OF AIRBORNE ASBESTOS FIBRES— I. CROCIDOLITE FROM KURUMAN AREA, CAPE PROVINCE, SOUTH AFRICA

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Abstract
The dimensions of airborne fibres collected at an underground mine and two mills producing crocidolite in the Kuruman area of Cape Province, South Africa, and of those collected at a plant manufacturing pipes in South Africa using Cape crocidolite and chrysotile asbestos are reported. The measurements were made using a transmission electron microscope, a scanning electron microscope and a light optical microscope. There was no apparent change in diameter with stage of processing although in certain processes, such as cutting asbestos cement pipe, the presence of chrysotile fibres altered the size distribution markedly. However, there was some change in length with stage of processing. The finding that the observed diameter distributions in airborne samples in this study are similar to those previously reported in the lungs of workers exposed to Cape crocidolite may indicate that, if diameter is the important parameter in relation to health effects, the hazard associated with exposure to Cape crocidolite should, dose for dose, be similar for all stages of processing. The proportion of long fibres in the air has been found to be very small and observations on very large numbers of fibres are necessary to confirm their presence.