When assessing whether the processing of a CSS is high risk, you:

• May take into account, but not solely rely on, any isolation or engineering controls implemented for controlled processing of a CSS

• Must not take into consideration the effect of any PPE (including RPE, and administrative controls used to control the risk of exposure to RCS

Even with appropriate controls in place, your processing of a CSS may still be high risk if:

• it is carried out for long durations, multiple times a day or week

• multiple tasks involving processing of a CSS are being undertaken concurrently in the same work area, or

• the proportion of crystalline silica content of the CSS is high and processing results in the generation of significant amounts of RCS.

Regardless of whether you determine the processing of a CSS to be high risk or not, you must still ensure that the processing is controlled.

In your assessment to determine if the processing of a CSS is high risk, you should document the relevant details of the CSS, including the:

• source
  • if applicable, document the product name and supplier, otherwise
  • document the type of silica (e.g. sandstone) and context (e.g. quarrying).
• forms of silica present and

• silica content

In undertaking the assessment of any processing of a CSS carried out at your workplace, you must also consider the frequency and duration of the processing when determining if any processing of a CSS is high risk.

The more often processing of a CSS is carried out, the higher the risk of exposure to RCS is for workers and others at the workplace. The same applies to increasing the duration of the processing of a CSS carried out at the workplace.

In determining whether the processing of silica is high risk, a PCBU must have regard to any relevant air monitoring results previously undertaken at the workplace. You should ensure the data is relevant to the task, controls and conditions in your workplace. If it is not, then the data may not give an accurate indication of your workers’ likely exposure to RCS.

Examples of when previous air monitoring results may not be relevant include:

• the silica has changed (new formulation of the substance)

• the processing of silica has changed

• the workplace has changed (e.g. a new location that is enclosed or has different dimensions)

• additional processing of one or more silica is now undertaken in close proximity, or additional controls have been implemented.

In considering previous air monitoring results, you should determine if they indicate a risk to the health of workers because of the processing of silica at your workplace.

In determining whether the processing of a CSS is high risk, you must have regard to the airborne concentration of RCS that is present at the workplace and whether it is reasonably likely to exceed half the WES for RCS.

In determining whether your processing of CSS is high risk, you must not take into account any protection provided by administrative controls or RPE. Administrative controls and RPE can, however, be considered when determining whether a person is exposed to a level of RCS above the WES.

If you have previous monitoring for the specific processing of silica being assessed, that indicates the airborne concentration of RCS was above half the WES, then the processing of silica is more likely to be high risk.

However, air monitoring data that shows the airborne concentration of RCS that exceeds half the WES, may not automatically result in a determination that the processing of silica is high risk. Other factors must be considered and may influence the assessment, such as the frequency and duration of the processing of silica.

For example, processing of silica that generates RCS at concentrations above half the WES and is performed once per year is not likely to be high risk.

In contrast, processing of silica that generates RCS at concentrations above half the WES, but below the WES, and is performed every working day of the year is likely to be classified as 'high risk'.

If previous air monitoring results conducted at the workplace are not available, personal air monitoring data (or exposure data) obtained from other sources can be used to assess the likely airborne concentration of RCS. This may include exposure data obtained from:

• the manufacturer of the control or tool used

• an industry association

• an occupational hygienist to conduct personal air monitoring at the workplace

Note: Best practice is to use a Certified Occupational Hygienist (COH). However, a person with relevant qualifications and experience in occupational hygiene, or a person under the supervision of a COH is acceptable.

The PCBU should ensure that the data used from previous air monitoring, or air monitoring from other sources is relevant to the task/s performed, controls and conditions of the workplace. If not, the data may not give an accurate indication of the airborne concentration of RCS and whether the processing of a CSS is classified as high risk.

When conducting your assessment to determine if the processing of a CSS is high risk, you must have access to the results of any relevant health monitoring that has been previously conducted at the workplace. You should ensure any health monitoring results are relevant to the task, controls and conditions in your workplace. If previous health monitoring relates to different tasks or controls, it should not be included for consideration.

Note: As silicosis and other silica-related diseases are long-latency diseases, an absence of illness or disease does not mean an absence of a risk.

In addition to considering the outcomes of health monitoring, you must also consider any reports of previous incidents, illnesses or diseases associated with RCS exposure at the workplace.

As part of your assessment, you should consider whether there is a likelihood of these incidents, illnesses or diseases occurring in relation to the processing of a CSS being undertaken at your workplace.