21 Characterisation of airborne particulate exposure at a gold mine tailings dam using real-time personal dust monitors and other methods

Abstract Background South African mining operations are progressively implementing real-time monitoring in their management airborne pollutant exposure. As part of this shift, this study investigated the application of real-time personal dust monitors in conjunction with other methods to characterise personal exposure to airborne particulates at a tailings dam. Methods Full shift side-by-side respirable dust (RD) personal exposure monitoring was conducted using NIOSH 0600 and either the TSI SidePak AM520 or the Nanozen DustCount 9000. Forty pairs of side-by side samples were collected across two sampling campaigns (16 SidePak and 24 DustCount). To investigate respirable crystalline silica (RCS) exposure, filters and bulk samples were analysed using X-Ray diffraction. The performance of the monitors was assessed using Bland-Altman plots and time-series data were examined in conjunction with activities performed and environmental data. Results Results showed varying agreement between the monitors and the gravimetric method. The SidePak recorded an average RD TWA of 52% (Range 8% to 145%) of the gravimetric method (mean bias = −0.089 mg/m3) while the DustCount recorded an average RD TWA of 38% (Range 7% to 114%) of the gravimetric method (mean bias = −0.107 mg/m3). Time-series data recorded peak exposures of up to 11 mg/m3 that were linked to activities and windy conditions on top of the dam. The bulk samples contained 85% quartz and personal RCS exposure varied between non-detectable and 0.170 mg/m3 (mean = 0.028 mg/m3). Conclusions Even though the real-time personal dust monitors generally under-sampled compared to gravimetric monitoring, they can be used in combination with other methods to characterise exposure to airborne particulates.