A worksite that looks clean can still put workers at risk. Respirable crystalline silica particles are so small in size they cannot be seen and visual inspection alone cannot measure whether dust concentrations are below Australian thresholds.
Objective monitoring is essential.
This article covers why silica dust remains a hazard even when it appears absent, what controls are required and how our tailored monitoring systems provide the data you need to protect workers.
Crystalline silica is a mineral form of silicon dioxide. Respirable crystalline silica refers to the fraction of airborne particles small enough to bypass the nose and throat and reach the deep lung. This is typically particles smaller than 10 micrometres.
The health risks linked to prolonged silica exposure include:
Silicosis, a potentially fatal lung disease that can present as chronic, accelerated or acute forms
Lung cancer
Chronic obstructive pulmonary disease (COPD)
Kidney disease and elevated tuberculosis risk
Symptoms of these diseases can take years to appear, which makes prevention and early detection through monitoring essential.
Australia has set a clear standard for RCS: 0.05 mg/m³ measured as an eight-hour time-weighted average. This standard applies to all sites, especially those working with CS containing materials such as concrete, sandstone and brick.
Respirable crystalline silica particles are smaller than 10 micrometres. At that size, they are invisible to the naked eye, but remain suspended in air and can be inhaled deep into the lungs. A workspace that appears dust-free may still contain airborne RCS concentrations above safe levels.
But that dust isn’t only a risk when suspended in the air. When it settles on surfaces, tasks like sweeping, walking across the shop floor or using compressed air can re-release particles into the air. That means exposure can occur long after a dust generating activity has ceased.
In short, visual cleanliness does not correlate with RCS concentrations. If you can’t measure it, you can’t confirm that it’s safe.
High risk tasks that generate respirable crystalline silica include:
Cutting, grinding, drilling, and polishing concrete, brick, tiles or stone
Demolition and jack-hammering
Wall chasing and dry sanding
Sandblasting and abrasive blasting
Crushing, milling and stockpile handling in mining
Earthworks, blasting and conveyor drop zones
Even tasks that appear low risk, such as sweeping settled dust or transferring material between stockpiles, can produce airborne RCS if the dust is fine enough.
But regulations don’t just focus on the activity, they also focus on the material. Those with silica content above 1% are considered high risk and require silica risk control plans in order to be used.
Visual checks may reveal bulk accumulations and large particles, but they cannot identify particles below 10 micrometres, the size that causes disease, so visual inspection alone is not enough.
Preventing exposure to respirable crystalline silica requires a hierarchy of controls. Elimination of silica hazards is the most effective control method; where elimination is not practicable, substitution and engineering controls take priority, followed by administrative controls, with respiratory protection the last line of defence.
Engineering controls reduce dust at its source to maintain exposure limits. The primary dust control measures for silica include:
Water suppression: Wet suppression methods, such as on tool water feeds, should be used during cutting and grinding to control dust.
Local exhaust ventilation (LEV): LEV captures dust at the point of generation using ventilation systems. Shrouded tools, ducted extraction and bench-mounted systems all fall into this category.
Air scrubbers: Air scrubbers with HEPA filtration remove particles as small as 0.3 micrometres, providing additional ambient air cleaning in enclosed work areas.
Equipment enclosures: Enclosed cabins on earthmoving equipment, isolated cutting stations and pre-designed service routing all reduce the number of workers exposed.
It is important to note that any engineered control requires regular inspection and maintenance to ensure its efficacy.
Administrative controls include scheduling high-dust tasks to limit worker exposure duration, rotating workers between tasks, confining heavy silica work to less-staffed shifts and restricting access to active cutting areas. Consistent and effective housekeeping using damp cleaning methods and filtered vacuums can minimise dust settlement.
Training is also essential. Workers need practical knowledge of how silica dust forms, how controls function, correct use of water suppression and LEV and the importance of hygiene practices to avoid take-home exposure. Training is required by SafeWork WA and records must be retained for five years after an employee leaves.
Employers must provide respiratory protective equipment (RPE) when exposure cannot be eliminated or controlled below the standard. RPE is the last resort in the hierarchy and should never be seen as a substitute for engineered controls.
Respirator selection depends on the exposure level. P2 or P3 filter face masks suit most tasks, while powered air-purifying respirators (PAPR) are recommended for prolonged high-hazard tasks or where workers have facial hair that prevents a seal with full face masks.
To ensure the effectiveness of RPE, it is recommended that fit testing is conducted before first use, then annually, or when a worker’s facial condition changes. ENVSS conducts quantitative fit testing for both respiratory and hearing protection equipment either on site or at our West Leederville facility. Click here to arrange a booking.
If exposure levels cannot be controlled below standards and RPE is necessary, it may also be worth considering personal exposure monitoring. Situations where this can prove useful include:
Introducing new materials such as engineered stone or high-silica concrete
Modifying or replacing control equipment
After accidental dust releases or control failures
When workers report respiratory symptoms
During baseline assessments for health monitoring programs
Personal monitoring typically includes respiratory health assessments (lung function tests etc.), questionnaires and, in some circumstances, imaging. ENVSS also conducts re-assessment to confirm whether controls are proving effective over time in the face of equipment wear and operational changes.
Australia’s workplace exposure standard for RCS is 0.05 mg/m³ as an 8-hour TWA. Silica exposure limits are set at 50 μg/m³ for general industry under OSHA’s silica rule. The MSHA rule for mining allows 100 μg/m³ of silica exposure. For WA operations running extended shifts, adjustments to the allowable concentration apply.
We compare monitoring results against Australia’s workplace exposure of 0.05 mg/m³ (as an 8-hour TWA). Results that consistently exceed 50% of that standard suggest that controls are degrading and health and compliance is at risk.
Our team assist your project managers with monthly or quarterly trend analysis, assessing whether maintenance issues, operational changes or other factors are affecting exposure. Should results suggest the need for action, we help with:
Reviewing and improving engineering controls
Retraining workers on safe systems of work
Increasing respirator use until controls are corrected
Documenting corrective actions taken
Under WA regulations, air monitoring records must be retained for 30 years.
Our team provides silica exposure assessment and air monitoring services to projects across Western Australia. Our team has practical experience on active mine sites, construction projects and industrial facilities where silica dust is present.
Our silica monitoring services include:
Personal exposure sampling using calibrated pumps and cyclone samplers
Area air monitoring to identify dust sources and assess control effectiveness
Defensible data collection with full QA/QC procedures and accredited laboratory analysis
Monitoring program design tailored to your site, materials, and shift patterns
Support with regulatory compliance and record keeping under WA WHS legislation
We mobilise experienced field technicians and specialist monitoring equipment. They understand the practical realities of working on remote sites, managing extended rosters and delivering data that stands up to regulatory scrutiny.
Our knowledge of WA environmental and occupational hygiene regulations means we can help your team build safe systems of work supported by reliable monitoring data, not assumptions.
A dust-free worksite does not guarantee low silica risk.
The only way to confirm whether your RCS controls are working is to measure airborne concentrations against WA exposure standards. Our team designs tailored monitoring programs that gather the evidence your business needs to protect workers and demonstrate compliance.
Click here to speak with the ENVSS team and discuss your silica monitoring requirements.