Personal respirable dust and respirable crystalline silica exposure in two shafts and a concentrator of a Zambian copper mine

Abstract

Objectives: Since the 1920s, Zambia's mining sector has experienced growth, which has increased the number of mine workers employed in the industry. Consequently, the potential for occupational exposure and prevalence of occupational diseases have also increased. Unfortunately, Zambia does not currently have legislative guidelines for workplace air monitoring and compliance. This study's objectives were to evaluate copper miners' personal exposure to respirable dust and respirable crystalline silica (RCS) and to assess workplace compliance using the European Standard for workplace air monitoring and measurement (EN689:2018). Methods: This cross-sectional study collected 100 personal respirable dust exposure samples at a Zambian copper mine in 2023. These samples were weighed using NIOSH method 0600 and analyzed for crystalline silica using Fourier transform infrared spectroscopy (KBr pellet) (NIOSH method 7602). Additionally, 253 respirable dust exposure measurements collected at the mine between 2017 and 2022 were included for comparison. Results: The median respirable dust exposure for the 2023 exposure measurements was 0.200 mg/m3 (95th percentile 2.871 mg/m3 ) compared to 0.400 mg/m3 (95th percentile 3.050 mg/m3 ) for the historic data. The median RCS exposure was 0.012 mg/m3 (95th percentile 0.163 mg/m3 ). Using EN689:2018, it was found that from 15 work areas, only six work areas complied with the standard for respirable dust exposure and only seven work areas complied with the standard for RCS exposure. Conclusions: At the mining site, several work areas had substantial exposure to respirable dust and RCS. Therefore, management needs to prioritize these areas when implementing control measures to reduce dust exposure. For the Zambia mining industry to manage exposure to respirable dust and RCS, it is necessary to implement standardized monitoring strategies. This study has demonstrated that EN689:2018 can be used successfully to determine compliance among Zambian mining work areas.