Silica Assessments and Air Monitoring

What is Silica and why is it hazardous?

Crystalline silica is found in sand, stone, concrete and mortar. It is also used to make a variety of products including artificial stone products (such as kitchen and bathroom benchtops), bricks and tiles.

When workers process materials containing crystalline silica by using power tools or other machinery, dust particles are generated that are small enough to lodge deep in the lungs and cause serious illness or disease including silicosis.

These dust particles are defined as Respirable Crystalline silica (RCS).

Work activities generating silica dust

Examples of work activities involving respirable silica are:

• using power tools to cut, grind or polish natural and engineered stone countertops
• excavation, earth moving and drilling plant operations
• clay and stone processing machine operations
• paving and surfacing
• mining, quarrying, mineral ore treating processes
• mechanical screening
• cutting fibre cement products
• road construction and tunnelling
• construction labouring and demolition
• brick, concrete or stone cutting; especially using dry methods
• abrasive blasting
• foundry casting
• angle grinding, jack hammering and chiselling of concrete or masonry
• hydraulic fracturing of gas and oil wells
• pottery making
• crushing, loading, hauling and dumping of rock, and
• clean-up activities such as sweeping.

Workplace requirements

The primary duty of employers (or PCBU’s) is to assess and manage the risk of respirable silica.

Air monitoring for respirable crystalline silica

Air monitoring is used in workplaces where dust is generated when working with products containing silica.

Under regulation WHS 49 and 50 air monitoring is required if there is a potential risk to health or a possibility that the exposure limits could be exceeded.

In simpler terms, this is done to determine if workers are at risk from exposure to RCS, or if you are unsure of whether the amount of RCS exceeds safe levels.

Air monitoring must be caried out by a hygienist or a similarly qualified person. In a workplace, air monitoring must be measured in a worker’s breathing zone. This is done for the duration of a worker’s shift to gauge the average amount they could be exposed to during normal work activity. The filter is then analysed in a lab with the results are compared against the Workplace Exposure Standard.

Static or boundary monitors can also be used when a monitor pump and air sampling filter are set around the site to see if controls are adequate to ensure that the public or other receptors are not at risk.

Air monitoring is a method of measuring airborne hazardous substances. It is not a control measure, but can be used to check the effectiveness of the control measures you implement to minimise the risks of exposure to silica dust.

Assessments

Results record where and when the monitoring took place, the type of work carried out and the control measures. Reports should identify the source of the potential exposure, how well the controls measures worked and whether any changes are required to reduce dust levels.