If your workplace handles or generates respirable crystalline silica (RCS) or respirable dust, one of the most common questions is: Are we legally required to conduct air monitoring?
The short answer is: If you cannot be certain that exposure is below the WES (Workplace Exposure Standard of 0.05 mg/m³ for RCS), you must monitor.
This article explains the legal basis for this requirement, which employers and industries are most likely to be obligated, what happens if you don’t monitor when you should, and how to know if you’re in the “uncertainty zone” that triggers monitoring.
The Legal Basis: The WHS Act and the “Uncertainty Trigger”
The Work Health and Safety Act 2011 (and equivalent state legislation) places a primary duty on all PCBUs (persons conducting a business or undertaking—essentially, employers and self-employed people) to ensure, so far as reasonably practicable, the health and safety of workers.
This duty includes identifying hazards and assessing risks. Crystalline silica is a known hazard, so if your work involves or creates silica dust, you must:
- Identify the presence of silica
- Assess the risk of exposure
- Implement controls in accordance with the hierarchy of controls
- Monitor to verify that controls are effective and that the WES is not exceeded
The key trigger for air monitoring is what occupational hygienists call the “uncertainty principle”:
If you cannot reasonably demonstrate through other evidence (e.g., historical data, similar industry data, task analysis) that exposure is below the WES, you must conduct air monitoring to confirm.
In other words, you don’t need to monitor every task all the time if you have strong evidence that exposure is already well-controlled. But if you’re unsure, monitoring is the appropriate response. The onus is on the employer to demonstrate safety; if you can’t, you must measure.
What Is a “Duty Holder” for Monitoring Purposes?
A PCBU is legally responsible for ensuring that monitoring occurs. This includes:
- Employers (businesses, organisations, government agencies)
- Self-employed people (sole traders, contractors)
- Principals (organisations that hire contractors to do work involving silica)
A PCBU may engage a competent occupational hygienist to conduct the monitoring, but the PCBU remains ultimately accountable for ensuring that:
– Monitoring is conducted
– Results are obtained and reviewed
– Controls are adjusted if WES is exceeded
– Records are kept for 30 years
Contractors and subcontractors do not escape this duty by virtue of being contractors. If a contractor controls a work environment where silica is present, they are a PCBU and must ensure monitoring occurs. In practice, this often means:
– The main contractor is the PCBU for the overall project
– The specialist silica contractor (e.g., stone fabricator, demolition company) is also a PCBU for their specific work
– Both parties have obligations, and coordination is essential
The Uncertainty Trigger Explained: When Must You Monitor?
You must conduct air monitoring if any of the following apply:
1. No Historical Data or Industry Baseline
If this is your first time performing a task or work activity involving silica, you have no internal data to show that exposure is low. For example:
– A building contractor is demolishing a concrete building for the first time—they must monitor
– A plumber is now breaking out concrete to install pipes—they must monitor
– A quarry is extracting a new ore body with different silica content—they should monitor to establish baseline
Action: Conduct initial air monitoring (personal and/or area samples) on representative workers/tasks.
2. Process Changes or Control Upgrades
If you’ve changed your work method, equipment, or controls, your previous data may no longer apply. For example:
– You’ve upgraded from wet cutting to dry cutting, or vice versa
– You’ve changed suppliers and now use a different stone product
– You’ve modified your equipment (new saw, new grinder, new extraction system)
Action: Re-monitor after the change to confirm that the new method does not result in higher exposures.
3. Regulatory or WES Changes
The WES for RCS was tightened on 1 September 2020 from 0.10 mg/m³ to 0.05 mg/m³. If you were monitoring under the old standard and your results were between 0.05 and 0.10 mg/m³, you are now required to take action, which may include enhanced controls and re-monitoring to demonstrate that you now comply with the new lower WES.
Additionally, the WES is due to transition again in December 2026. Employers should review current monitoring data against future limits well in advance.
4. Worker Complaint or Health Concern
If a worker reports health symptoms (cough, chest tightness, shortness of breath) or complains of visible dust, you must investigate. This may trigger the need for air monitoring to determine if exposure is a factor.
5. Regulator Inspection or Directive
If a WHS regulator (SafeWork NSW, WorkSafe Victoria, etc.) raises concerns about silica exposure during an inspection or issues a compliance direction, you must conduct or increase monitoring as directed.
Industries Where Monitoring Is Almost Always Required
Certain industries are presumed to involve significant silica exposure risk, and monitoring is standard practice:
Construction and demolition: Concrete cutting, jackhammer work, brick removal, grinding, sawing.
Mining and quarrying: Extraction and processing of silica-bearing ore (quartz, feldspar, sandstone, granite).
Tunnelling and underground work: Drilling, blasting, and excavation through silica-bearing rock.
Foundries: Sand handling, core-making, knockout, grinding.
Stonemasonary and fabrication: Cutting, grinding, polishing of granite, marble, sandstone.
Ceramics and refractories: Handling and processing of clay, feldspar, silica products.
Sandblasting: High-exposure activity; strict controls and monitoring are legally required.
Paving and road work: Crushing and laying of aggregate.
In these industries, not conducting air monitoring is a red flag for regulatory action. If you work in one of these sectors, assume monitoring is required and plan accordingly.
Industries Where Monitoring May Be Required, Depending on Tasks
Some industries involve silica exposure only in specific tasks:
General building maintenance and renovation: Monitoring may be required if work involves concrete cutting, grinding, or drilling.
Plumbing and electrical installation: Required if work involves drilling or breaking concrete.
Agriculture and soil work: Required if work involves crystalline silica-bearing soil disturbance or handling (e.g., diatomaceous earth handling).
Vehicle repair and manufacturing: May be required if work involves grinding, cutting, or abrading silica-bearing materials (e.g., grinding weld spatter, cutting composite materials with silica fillers).
For these industries, the decision hinges on whether the specific task generates silica dust and whether you can be certain that exposure remains below the WES.
What Happens If You Don’t Monitor When Required?
Failing to monitor when you are legally required to do so can result in:
Regulatory Enforcement
Improvement notice: The regulator issues a notice requiring you to conduct monitoring and correct any deficiency within a specified timeframe (typically 7–28 days for urgent matters).
Prohibition notice: In serious cases, the regulator may prohibit the work entirely until you can demonstrate that it is safe (via air monitoring and control evidence).
Infringement notice (penalty): A financial penalty is issued immediately, typically ranging from AUD $650 to $3,000 for a company, or AUD $325 to $1,500 for an individual (depending on the jurisdiction and severity).
Prosecution
If a failure to monitor results in a worker’s injury or death, or if there is a pattern of systematic non-compliance, the PCBU may be prosecuted under the WHS Act. Penalties for individuals can include imprisonment; penalties for bodies corporate can be very substantial (in the hundreds of thousands of dollars or more).
Personal Liability
Directors and senior managers can also be prosecuted for a breach of their due diligence duty, which includes ensuring that the business has appropriate monitoring and control systems.
Worker Compensation and Common Law Claims
If a worker develops silica-related disease (silicosis, lung cancer, COPD) and the employer did not monitor, the worker may claim:
– Workers compensation (medical expenses, loss of earnings)
– Common law damages (for pain and suffering, lost lifetime earnings)
– The employer’s failure to monitor is strong evidence of negligence and breach of duty
Who Conducts the Monitoring? The Competence Requirement
Air monitoring for silica must be conducted by a competent person. In Australia, this typically means:
- An occupational hygienist certified by the Australian Institute of Occupational Hygienists (AIOH)
- A consultant employed by a consulting firm with AIOH-certified staff
- An internal occupational hygienist (if the employer has one on staff)
- A laboratory technician (for sample preparation, but analysis must be supervised by a competent person)
A “competent person” is not simply someone with general safety knowledge. They must have:
– Formal qualification in occupational hygiene (degree or diploma level)
– Experience in air monitoring design and interpretation
– Knowledge of Australian WHS law and standards
– Understanding of sampling methods, equipment, and analytical techniques
– AIOH membership or equivalent recognised qualification
Verification: Always ask a potential consultant or contractor about their AIOH status or equivalent qualification. If they cannot demonstrate formal occupational hygiene credentials, they are not competent to conduct silica air monitoring.
Monitoring vs Risk Assessment: One Doesn’t Replace the Other
A common misconception: “If we’ve done a risk assessment, we don’t need to monitor.”
This is incorrect. Risk assessment and air monitoring serve different purposes:
Risk assessment (qualitative or quantitative) identifies hazards and evaluates the likelihood and severity of harm. A risk assessment can help you identify which tasks are likely to pose silica exposure risk and should be prioritised for controls.
Air monitoring (quantitative) measures actual airborne RCS concentrations and compares them to the WES. It tells you whether your controls are working in practice.
You need both:
1. A risk assessment to identify the hazards and design appropriate controls
2. Air monitoring to verify that the controls are effective and that the WES is not being exceeded
If you have only a risk assessment but no monitoring data, you cannot demonstrate compliance with the WHS Act’s requirement to “ensure health and safety, so far as reasonably practicable.”
Frequently Asked Questions
Q: If I employ only 5 people and we occasionally do tasks that might involve silica (e.g., drilling concrete), do I still have to monitor?
A: The WHS Act applies to all PCBUs, regardless of size. If you regularly perform silica-generating work, you must assess the risk and implement controls. If you cannot be certain that exposure remains below the WES (which is likely if this is occasional work with no historical data), you must monitor. Small business does not exempt you; however, you may engage a consultant to conduct monitoring rather than building in-house capability.
Q: Can we use the industry benchmark data (e.g., “stone cutting usually generates X mg/m³”) instead of monitoring our specific workplace?
A: Industry data is useful for initial risk assessment and can inform your control strategy. However, it is not a substitute for site-specific monitoring. Your workplace is unique: your equipment, processes, worker practices, and environmental conditions differ from industry benchmarks. You must measure your own workplace to confirm that exposure is below the WES. Industry data alone will not satisfy a regulator or a court if a worker is overexposed.
Q: How often must we monitor? Is once per year enough?
A: Monitoring frequency depends on the hazard level and control effectiveness. High-risk tasks (e.g., jackhammer work, grinding) typically require quarterly or more frequent monitoring. Once-yearly monitoring is generally insufficient for high-risk work; it may be acceptable for lower-risk, well-controlled tasks if baseline data demonstrates consistent compliance. Always discuss frequency with your occupational hygienist; they can advise on an appropriate schedule.
Q: If a worker requests health monitoring (medical surveillance), does that replace air monitoring?
A: No. Health monitoring (chest X-rays, lung function tests) is a complementary control, not a substitute for air monitoring. Health monitoring detects early signs of silica-related disease in workers; air monitoring demonstrates that you are controlling exposure to prevent disease in the first place. You may need both: air monitoring to show compliance, and health monitoring (if workplace exposure is above a trigger level) to detect early disease.
Q: If we hire a contractor to do silica-generating work, are we responsible for monitoring?
A: Yes, as the principal (PCBU), you have a duty to ensure that silica exposure is managed, including monitoring. You may require the contractor to conduct the monitoring (as part of the contract), but you remain accountable. Always include monitoring requirements in the contractor brief and verify that competent monitoring is being conducted.
Q: We’ve been told by a supplier that their product (e.g., stone, aggregate) is “low silica” or “silica-free.” Can we rely on this and skip monitoring?
A: Not entirely. Supplier claims may be accurate, but they do not eliminate your need to assess and monitor. Product composition can vary (different quarries, different batches, weathering, contamination). If this is critical to your compliance case, request test data from the supplier and conduct your own validation monitoring. A responsible supplier will provide technical data; if they won’t, treat the product as potentially high silica and monitor accordingly.
Summary
The requirement to conduct silica air monitoring is rooted in the WHS Act’s primary duty to ensure health and safety. If you cannot be certain that exposure is below the WES, monitoring is not optional—it is legally required. This applies to all PCBUs, regardless of business size or industry, though certain industries (construction, mining, foundries) are particularly subject to scrutiny.
Engaging a competent occupational hygienist to design and conduct your monitoring program is the best way to ensure compliance and protect your workers.
Anitech Group works with Australian employers to determine monitoring obligations, design monitoring programs, and interpret results. Unsure if your business is required to monitor? Our hygienists provide obligation-free advice.
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- FEATURE: 1200x630px. Split-screen image: left side shows a compliance checklist with a green checkmark over “Air Monitoring Required”; right side shows an occupational hygienist conducting a sampling session with a worker, with visible monitoring equipment (cassette sampler, pump).
