PARTICLE SIZE DISTRIBUTION OF AN AEROSOL AND ITS SUB-FRACTIONS

Particle size distribution of an aerosol and its sub-fractions was carried out as part of an epidemiological study by using a Retsch Precision High Volume Cascade Impactor. The impactor was used in the underground and surface mining operations as they are currently practised. It was also used in experimental stopes in gold, uranium and nickel mines where conditions of dry drilling were simulated. The impactor fractionates airborne dust into seven ranges of particle size from submicron to 32 μm aerodynamic diameter, when operating at 40 l. min−1 Since the impactor operated at high flow rate, sufficient dust was collected to permit further analysis of the sub- fractions, such as free crystalline silica or metal (iron). A unique system was designed by using a venturi and compressed air for its use in an underground environment. For some tasks the particle size distribution of the sub-fraction was found to be similar to that of the total dust but different for other tasks.