Respirable Crystalline Silica (RCS) monitoring and analysis

Silica is silicon dioxide (SiO₂), a naturally occurring mineral that forms a major component of most rocks and soils. There are non-crystalline and crystalline forms of silicon dioxide. Mechanical processes such as crushing, cutting, drilling, grinding, sawing or polishing products containing silica can generate respirable particles (PM₁₀) small enough to penetrate deep into the lungs, which can cause irreversible lung damage. These compounds are referred to as respirable crystalline silica or RCS.

There has been significant work at a state and national level to understand the health implications for workers − including a review of safe levels − since they may be exposed to hazardous levels of RCS. More information can be found in Silicosis in Mining and Quarrying in South Australia information sheet.

The EPA, with input from SA Health, undertook an extensive literature review of the modern criteria for RCS in ambient air for mining and extractive industries. Based on this, the EPA is adopting an interim RCS criterion for the mining and extractive industries of 3 μg/m³ (annual average) for the PM₁₀ size fraction of dust in ambient air. The PM₁₀ size fraction selected is based on a precautionary approach, which will ensure communities are well protected from any adverse impact of RCS in ambient air.

Hanson is undertaking a 12-month crystalline silica monitoring campaign to determine background concentrations from its current operations. The results of the campaign can then be used to determine if the concentrations are within acceptable limits inside the quarry and the likely predicted ground level concentration at receptors.

After active engagement with the EPA, DEM and other stakeholders, on 7 July 2022 Hanson commenced its Ambient Air Quality Campaign for Respirable Crystalline Silica (RCS). The EPA’s criterion for RCS is that Hanson must operate below the 3 micrograms per cubic metre (μg/m3) on an annual average. At this stage we are pleased that Hanson is undertaking a regular RCS monitoring and providing data on a regular basis to the EPA. Early data indicates that this is currently being achieved however the EPA will conclude whether Hanson is compliant after a full 12 months of monitoring is complete and will work with DEM to ensure compliance.