Do Recycling and Crushing Sites Need Silica Air Monitoring?

One of the most common questions we get from recycling and crushing operators is: 'Do we have to do silica air monitoring?' The honest answer is — not automatically. Whether monitoring is required depends on what the business already knows about its exposures and the controls in place.

Under the WHS Regulations 2012 (SA), an air monitoring obligation arises in two main situations: where the person conducting a business or undertaking (PCBU) is not certain on reasonable grounds that the airborne concentration of a hazardous chemical (including respirable crystalline silica) does not exceed the workplace exposure standard; or where monitoring is necessary to determine whether there is a risk to health.

The current workplace exposure standard for respirable crystalline silica in Australia is 0.05 mg/m³ as an 8-hour time-weighted average. This is a statutory health-based limit, not a target — it is the level above which an exceedance must be addressed.

Concrete crushing, brick and masonry processing, and screening of mixed C&D material can generate RCS at concentrations that approach or exceed this limit, particularly when controls are inadequate or have degraded. Tasks like jaw and impact crushing, dry screening, conveyor transfer points, stockpile management and front-end loader work are well-recognised exposure sources.

If the business cannot point to documented evidence — risk assessment, similar exposure group analysis, manufacturer data or prior monitoring — that confirms exposures stay below 0.05 mg/m³, then air monitoring is the mechanism the regulations expect operators to use.

A practical silica monitoring plan typically includes: identification of similar exposure groups (e.g. crusher operators, loader operators, maintenance, plant supervisors); selection of representative workers and tasks; personal sampling using cyclone samplers in accordance with AS 2985 or equivalent; analysis at a NATA-accredited laboratory; comparison to the workplace exposure standard; and a written report with corrective actions where required.

Monitoring is not a one-off exercise. Where exposures are close to the standard, where processes change, where new input streams arrive, or where controls are modified, repeat monitoring is the way to confirm that controls remain effective. Where exposures are well below the standard and processes are stable, the frequency can be reduced — but the rationale should be documented.

For most South Australian operators, the right starting point is a baseline assessment: a site walk-through, a documented exposure assessment, and a recommendation on whether monitoring is required, and if so, for which roles and how often. AX4 prepares this kind of plan, coordinates the sampling, and delivers a report that is defensible if SafeWork SA asks to see it.

Related in this cluster: the broader dust and silica risk picture, asbestos contamination in C&D recycling, the documentation a site should hold, and dust control measures for crushing, screening and stockpiling.