Construction dust is created when working with materials such as cutting timber studs, chasing or cutting into concrete, mixing plasterboard mortar or during demolition work. The dust usually contains silica (the most abundant mineral on earth found in large amounts in sand, sandstone, granite and quartz), non-silica (like gypsum, cement, limestone and marble) or wood (softwood, hardwood and wood-based products such as MDF and chipboard).
Planning and risk assessment
You should consider the risks of dust exposure before work starts to ensure appropriate actions are taken to limit the amount of dust generated during work tasks.
Anyone working on a construction site could be exposed to hazardous levels of silica dust, but those especially at risk include bricklayers, carpenters and plasterers (when installing fibre cement products), labourers, demolition workers and floor finishers.
Hierarchy of Controls
Use the following Hierarchy of Controls to determine what level of control you need to manage the risks associated with breathing in dust:
- Elimination – work with the building designer to standardise room sizes and eliminate the need to cut materials to length on-site by having materials pre-cut to length before being delivered
- Substitution – substitute materials for ones that don’t contain silica and use fibre cement shears instead of circular saws or grinders
- Engineering – use on-tool dust collection and dust extraction when cutting materials with saws or other tools that produce dust and use water suppression when demolishing buildings
- Administration – perform cutting tasks outside in well-ventilated areas and rotate workers on cutting tasks to reduce exposure
- Personal protective equipment – use the right respiratory protective equipment (RPE) for the task and ensure it's fit-for-purpose. Ensure the RPE fits the individual correctly using fit testing. RPE should never be used as the only control measure for dust exposure. Train workers on the correct use and maintenance of RPE.
Respirable Crystalline Silica (RCS)
While breathing in any quantity of dust is a health risk, silica dust is particularly harmful because the particles are small enough to be inhaled into the lungs. When inhaled into the lungs it can cause scarring and irreparable damage that over time leads to respiratory diseases such as silicosis, lung cancer and even renal failure.
Respirable crystalline silica (RCS) is a hazardous substance, which requires a risk assessment to identify whether it poses a significant risk in your workplace. There is no recognised safe level of exposure to RCS but you mustn't exceed the standard of 0.1mg/m3 in an eight-hour work day.
You must monitor the air and workers' health to determine levels of exposure and assess the risks for anyone performing ongoing work with silica containing products.
Master Builders gets lots of questions about wearing respirable protective equipment, for example tight-fitting respirators and the legal requirement to fit test individual workers. Here's some of the most common ones:
What is fit testing and why is it required?
Fit testing detects if air is leaking into a respirator through gaps in the seal between the respirator face piece and the worker’s face.
The performance of any tight-fitting respirator relies heavily on having a good seal between the respirator and the wearer’s face. If the respirator doesn’t create an effective seal, contaminated air can leak into the respirator.
Respirators are not a one-size-fits-all item of Personal Protective Equipment (PPE). As each individual person’s face varies significantly in shape and size, it’s important that a suitable tight-fitting respirator is chosen for each worker.
How is fit testing done?
There are two methods used for fit testing:
- Qualitative fit testing – a pass/fail test that relies on the wearer’s ability to taste or smell a test agent. This type of test can be used on half-face respirators.
- Quantitative fit testing – uses specialised equipment to measure how much air leaks into the respirator. This type of test can be used on half-face and full-face respirators.
When and how often should fit testing be done?
Fit testing should be carried out before the respirator is selected and used by a worker for the first time. It should also be carried out:
- At least once per year to ensure it continues to fit adequately
Whenever there’s a change in the wearer’s facial characteristics or features which may affect the facial seal, such as weight loss or gain.
Who can complete a fit test?
Any fit testing should be carried out by a competent person. This could be someone within your business who has appropriate qualifications and experience, the manufacturer or supplier of the respirator, or a consultant, such as a hygienist of medical professional.
How do I know if a worker’s been fit tested?
Once a worker passes a fit test, a written record of the results should be kept for each worker with information that should include:
- Type of test performed (qualitative vs. quantitative)
- Make, model, style and size of respirators tested
- Date of the test
- Result of the test.
This information will guide you – as their employer – to which type of respirator they have been fit tested to use safely. Workers are only permitted to use the specific respirator outlined in their written record.
We recommend that this information be produced in the form of a fit test record card that can be easily kept on hand by the worker.
It is important to choose the right respirator for the job. The fit of a respirator to a worker's face is critical . Have workers fit tested to ensure the respirator is comfortable and capable of giving the right level of protection. The amount of time the respirator is worn also needs to be considered.