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Respirable crystalline silica (RCS)

RCS is fine silica dust under 10 microns from cutting concrete, brick, fibre cement, stone. WES 0.05 mg/m³ over 8-hour TWA. WEL transition from 1 December 2026.

By Chalkline. Last updated 14 May 2026. Verified 14 May 2026.

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Respirable crystalline silica (RCS) is fine silica dust under 10 microns in particle size, generated when materials containing crystalline silica are cut, drilled, ground, sanded, or broken. The respirable fraction is small enough to pass through the upper airways and lodge in the lungs, where it causes silicosis, lung cancer, chronic obstructive pulmonary disease, and kidney disease.

Sources on a residential build:

  • Fibre cement sheet (cutting Villaboard, HardieFlex, Compressed sheet, soffit lining).
  • Concrete (cutting, grinding, core-drilling, demolition, scabbling).
  • Brick and block (cutting, grinding, cleanup of mortar).
  • Stone (engineered stone benchtop fabrication, natural stone cutting).
  • Tile (wet tile saw work, edge grinding for fits).
  • Plasterboard (sanding joint compound; the gypsum core has lower RCS but compound contains some silica).
  • Autoclaved aerated concrete (AAC) (cutting Hebel panels and blocks).

The Australian exposure standard. Schedule 14 of the model Work Health and Safety Regulation sets the Workplace Exposure Standard (WES) for RCS at 0.05 mg/m³ over an 8-hour time-weighted average (TWA), with no short-term exposure limit (STEL) or peak limit. From 1 December 2026, the WES becomes a Workplace Exposure Limit (WEL): the change is a regulatory tightening of how exposures must be measured, calculated, and demonstrated, not a change in the headline number. The 0.05 mg/m³ number itself is one of the lowest exposure standards in any Australian airborne-contaminant schedule.

Hierarchy of controls. Like every WHS hazard, RCS controls apply in priority order:

  1. Eliminate: design out the cut (use pre-cut sheets, factory-finished benchtops).
  2. Substitute: use a lower-silica product where one exists (some engineered stones now offer <10% silica; many states have banned high-silica engineered stone outright).
  3. Isolate: cut in a dedicated bay with extraction and barriers.
  4. Engineering controls: wet cutting, on-tool dust extraction.
  5. Administrative: rotate workers off high-RCS tasks, post warning signage, written SWMS.
  6. PPE: P2 or P3 respirator, eye protection. Respirator-only is the last resort and the most exposed to enforcement scrutiny.

Health-monitoring trigger. When workers are regularly engaged in HRCW that involves RCS exposure, the PCBU must arrange health monitoring (chest imaging, respiratory function tests) at regular intervals through an authorised registered medical practitioner.

For builders. Three practical points:

  1. Wet cut or extracted dry cut, every time. No “just for a quick cut” exceptions; the dust dose accumulates over a career.
  2. Engineered stone work: the regulatory landscape changed sharply in 2024 (QLD banned high-silica engineered stone fabrication from 1 July 2024; other states followed or in progress). Check state-specific bans before quoting kitchen benchtops.
  3. Health monitoring records stay with the PCBU. If you take on regular RCS-exposed work, the records bind to the business.

Also known as: RCS, silica dust, fine silica.

Category: WHS / silica / exposure standards.

See also

Last updated: 2026-05-14. Verified: 2026-05-14.

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