Assessing Compliance with Evolving Exposure Standards: Respirable Crystalline Silica (RCS) Exposure in Western Australian Mining

Abstract

The link between occupational exposure to Respirable Crystalline Silica (RCS) and silicosis, a potentially fatal respiratory disease, has been well-established, leading to global reductions in RCS Exposure Standards (ES). In Western Australia (WA), RCS data have been collected by the Department of Energy, Mining, Industry Regulation and Safety (DEMIRS) from 1986 to 2024 (n = 144,141). These results were analysed to assess the impacts of recent changes to the ES on compliance. Findings suggest that the WA mining sector, regardless of commodity type, is compliant with RCS exposures as assessed against the 0.05 mg/m³ ES (2019). Laboratory technicians, exploratory drilling, miscellaneous trades/utilities, trades assistant, sample preparation, and sampler/sample operator are SEGS that had the highest RCS exposures. Exposure assessment did not account for the protection provided by respiratory protective equipment (RPE). In the WA mining sector, a robust respiratory protection regime is enforced that includes respirator fit testing, and this is most likely the case throughout Australia. On the balance of epidemiological evidence, industry compliance over decades, reducing exposure profiles, and robust RPE programmes, it could be argued that further reductions to the RCS exposure standard are not justified. Regulators need to consider the protection provided by respirators in exposure assessment.

Keywords: lung disease; mining; respirable crystalline silica; workplace exposure standards.

Figure 1

Mean RCS concentrations with 95% confidence intervals (1987–2024). Note: The red line from 1986 to 2019 is the repealed ES. The shorter red line from 2019 to 2024 is the current ES, and the blue line represents the proposed ES.

Figure 2

Mean and 95% CI of RCS concentration for selected SEGs (2020 to 2024). The red lines are the repealed ES. The blue lines represents the proposed ES.