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Managing Risks of Respirable Crystalline Silica

What is Respirable Crystalline Silica?​

Respirable crystalline silica (RCS) is fine dust containing silica particles small enough to be inhaled deep into the lungs. Silica is a natural component of many materials including:

Dust particle sizes

  • Sand, soil, granite, sandstone
  • Concrete, mortar, brick, tiles
  • Engineered stone (artificial stone benchtops, up to 95% silica)

When these materials are cut, ground, drilled, crushed, or demolished, silica dust is generated.

[!warning] Serious Health Hazard Breathing silica dust causes silicosis (incurable lung disease), lung cancer, chronic obstructive pulmonary disease (COPD), and kidney disease.

High-Risk Construction Activities​

Dry cutting/grinding/drilling:

  • Concrete, masonry, brick, tiles
  • Engineered stone (kitchen benchtops, bathroom vanities)
  • Natural stone, sandstone
  • Asphalt, roadways

Abrasive blasting:

  • Using sand or silica-containing abrasives

Demolition:

  • Concrete structures
  • Brick and masonry buildings

Tunneling and excavation:

  • Rock containing silica

Exposure Standard​

WHS Regulation 50:

  • 0.05 mg/m³ (8-hour time-weighted average)

[!important] Extended Shifts The TWA must be adjusted for shifts longer than 8 hours or weeks longer than 40 hours, and must not be adjusted upwards.

This is a very small amount—effective dust control essential.

Who Has Duties?​

PCBUs​

Must:

  • Identify if silica dust generated
  • Assess risks of exposure
  • Implement dust control measures following hierarchy of control
  • Conduct air monitoring
  • Provide health monitoring
  • Provide information and training
  • Keep exposure records

Designers, Manufacturers, Suppliers​

Must:

  • Design plant/processes to minimize silica dust
  • Provide information on silica content
  • Include dust control features in equipment

Risk Management Process​

1. Identify Hazards​

Check if materials contain silica:

  • Concrete, brick, stone, tiles (assume contain silica)
  • Engineered stone (very high silica content)
  • Safety Data Sheets for manufactured products
  • Natural stone and rock

Identify dust-generating activities:

  • Cutting, grinding, drilling, sanding
  • Demolition, breaking, crushing
  • Dry sweeping of silica-containing dust

2. Assess Risks​

Consider:

  • Silica content of material (engineered stone = extreme risk)
  • Type of activity (dry cutting worse than wet)
  • Duration and frequency of exposure
  • Enclosed vs. open-air work
  • Number of workers exposed

Risk Indicators:

  • Visible dust clouds
  • Dust settling on surfaces
  • Workers coughing or irritated

3. Control Risks: Hierarchy of Control​

Level 1: Elimination

  • Order pre-cut materials (no on-site cutting required)
  • Use alternative materials (lower silica content)
  • Design out need for cutting/modification

Example: Pre-fabricated concrete panels eliminate on-site cutting.

Level 2: Substitution

  • Substitute lower-silica alternatives where possible
  • Use non-silica abrasives for blasting

Example: For certain applications, use low-silica aggregate concrete.

Level 2: Engineering Controls (CRITICAL)

Engineering controls are the primary defense against silica dust:

On-Tool Water Suppression:

  • Continuously supplies water to cutting/grinding point
  • Binds dust before it becomes airborne
  • Mandatory for most silica work

On-Tool Dust Extraction:

  • Captures dust at source via vacuum system
  • HEPA-filtered vacuum (H or M-class)
  • Effective for drilling and some grinding

Operational view of local exhaust ventilation

A worker cutting/grinding with on tool dust extraction

Combined Water + Extraction:

  • Most effective control
  • Example: Wet-cutting saw with vacuum shroud

Ventilation:

  • Local exhaust ventilation for enclosed work
  • Natural ventilation for outdoor work (still requires other controls)

Isolation:

  • Separate cutting area from other workers
  • Exclusion zones during high-dust activities
  • Enclose dust-generating processes

An example of an isolation booth used for automated wet cutting

Level 3: Administrative Controls

  • Limit time workers exposed to dust
  • Rotate workers to reduce individual exposure
  • Safe work procedures and Safe Work Method Statements
  • Regular housekeeping (wet methods or HEPA vacuum only—never dry sweep)
  • Training on silica risks and controls

Level 3: Personal Protective Equipment

[!warning] PPE is Last Line of Defense Never rely on PPE alone. Engineering controls must be primary.

Respiratory Protection:

  • P2 or P3 respirators (disposable or reusable)
  • Must be fit-tested to individual worker
  • Quantitative fit testing required
  • Replace when breathing resistance increases

For high-risk work (e.g., engineered stone):

  • Powered air-purifying respirators (PAPR)
  • Supplied-air respirators

Other PPE:

  • Safety glasses/goggles
  • Hearing protection (tools generate noise)
  • Work clothing (changed regularly, not taken home)

Personal protective equipment

4. Maintain and Review​

  • Inspect and maintain water suppression systems daily
  • Test dust extraction equipment regularly
  • Replace vacuum filters as needed
  • Check respirators before each use
  • Conduct air monitoring
  • Review controls after incidents

Engineered Stone—Specific Requirements​

Extremely High Risk: Engineered stone contains up to 95% silica. Special controls required.

Mandatory Controls:

  • On-tool water suppression for all cutting, grinding, drilling
  • On-tool dust extraction where water alone insufficient
  • Respiratory protection (P2/P3 minimum, PAPR recommended)
  • Health monitoring for all workers

Recommended Controls (Best Practice):

  • Silica Dust Control Plan (highly recommended tool for ongoing management)

Prohibited Practices:

  • Dry cutting (without water suppression)
  • Using compressed air for cleaning
  • Dry sweeping

Air Monitoring​

When Required:

  • Uncertain if exposure exceeds standard
  • To verify control effectiveness
  • After changing work methods or controls
  • Regularly for high-risk work (engineered stone)
  • Baseline Air Monitoring: Recommended when commencing work with engineered stone to establish exposure levels.

Who Conducts Monitoring:

  • Competent person (occupational hygienist)
  • Personal air samplers worn by workers
  • Samples analyzed by NATA-accredited laboratory

Worker's breathing zone

Results:

  • If exposure exceeds 0.05 mg/m³, immediate action required
  • Improve controls, re-monitor to confirm effectiveness
  • Keep records for 30 years

Health Monitoring​

When Required (WHS Reg 56)​

Health monitoring mandatory if worker:

  • Carries out ongoing work with silica materials, AND
  • Uses powered tools or equipment, OR
  • Is at risk of exposure exceeding 0.05 mg/m³

This includes:

  • All workers cutting, grinding engineered stone
  • Workers regularly cutting/grinding concrete, brick, stone
  • Abrasive blasters using silica abrasives

What Health Monitoring Involves​

  • Medical history and examination
  • Respiratory function tests (spirometry)
  • Chest X-ray or CT scan (baseline and periodic)
  • Conducted by qualified medical practitioner
  • Records kept for 30 years

Worker Rights:

  • Access to own health records
  • Confidential medical information
  • No cost to worker

See Health Monitoring for details.

Silica Dust Control Plan​

For ongoing silica work, prepare written plan including:

  • Tasks that generate silica dust
  • Risk assessment results
  • Control measures for each task
  • Air monitoring schedule
  • Health monitoring requirements
  • Training requirements
  • Review schedule

Practical Construction Example​

Scenario: Cutting concrete slabs for plumbing penetrations

Hazard Identification​

  • Concrete contains crystalline silica
  • Dry cutting generates respirable dust
  • Multiple cuts required daily
  • Workers exposed throughout project

Risk Assessment​

  • High risk: Regular exposure, high dust generation
  • Multiple workers involved

Controls Implemented​

Engineering:

  • Wet-cutting saw with continuous water supply
  • On-tool extraction for handheld grinder (backup)
  • Work outdoors where possible (ventilation)
  • Exclusion zone 3 meters around cutting

Administrative:

  • SWMS prepared for silica work
  • Trained operators only
  • Wet methods for cleanup (no dry sweeping)
  • Work clothing changed daily

PPE:

  • P2 respirators (fit-tested to each worker)
  • Safety glasses
  • Hearing protection
  • Gloves

Monitoring:

  • Air monitoring conducted (initial and periodic)
  • Results below 0.05 mg/m³ (controls effective)
  • Health monitoring arranged for all exposed workers

Review​

  • Daily check: Water system functioning
  • Weekly: Inspect equipment, confirm procedures followed
  • After project: Review effectiveness, update controls for next project

Clearance and Cleanup​

After Silica Dust Work:

Never:

  • Dry sweep or use compressed air
  • Allow dust to accumulate
  • Use standard shop vacuums (spread dust)

Always:

  • Wet wipe surfaces
  • Use HEPA-filtered vacuum (H or M-class)
  • Dispose of waste properly (sealed bags)
  • Clean work clothing (commercial laundry, not home)

Information and Training​

Workers must know:

  • Health effects of silica dust (silicosis, lung cancer)
  • How to identify silica-containing materials
  • Dust-generating activities
  • How to use control measures (water systems, extraction, PPE)
  • Importance of health monitoring
  • Never remove or bypass controls

Dust warning signs

Summary of Key Requirements​

For All Silica Work: ✓ Use water suppression or dust extraction ✓ Never dry cut, grind, or drill ✓ Use appropriate respiratory protection ✓ Conduct air monitoring ✓ Provide health monitoring ✓ Train all workers

For Engineered Stone: ✓ All above controls PLUS ✓ Mandatory water + extraction ✓ Higher-level respiratory protection (PAPR recommended) ✓ Silica Dust Control Plan ✓ Regular air monitoring