Silica dust from cutting concrete

Five questions a business works through

1. Is the material a crystalline silica substance?

   For a manufactured product, the code points to the safety data sheet, the label or the manufacturer. For natural ground, as on most civil construction sites, it says testing by a NATA-accredited laboratory, or equivalent, is the best way to know. Without testing or data, the business should assume the silica content is high.

2. Is the work “processing”?

   Processing means using power tools or mechanical plant to crush, cut, grind, trim, sand, abrasively polish or drill the material, among other things. The code’s examples include cutting brick, concrete or stone, angle grinding and jackhammering concrete or masonry, and cleaning up by sweeping or vacuuming silica dust. Hand tools count too if they expose someone to the dust.

3. Is the processing controlled?

   A business must not process a crystalline silica substance, or let a worker do it, unless the processing is controlled. That means three things together:

   • the risks are eliminated or minimised so far as is reasonably practicable;
   • at least one of these is used: isolating people from the dust, a fully enclosed operator cabin with high efficiency air filtration, an effective wet dust suppression method, an effective on-tool extraction system, or an effective local exhaust ventilation system;
   • anyone still at risk after that is given respiratory protective equipment and wears it.

   Respiratory protection on its own counts only where none of those five measures is reasonably practicable, and the code expects the business to be able to explain why.

4. Is it high risk?

   Before work starts, the business has to decide whether the processing is reasonably likely to put someone’s health at risk, looking at the task, the forms and share of silica, how often and how long people are exposed, whether airborne levels are likely to go over half the exposure standard, past air and health monitoring, and past incidents or illness. It may take isolation and engineering controls into account, without relying on them alone, but not respiratory protection or administrative controls. If it cannot decide, it must treat the work as high risk, and it writes the assessment down either way.

5. If it is high risk, what more is needed?

   • A silica risk control plan before the work, made with the workers and given to them before they start. For construction work, a safe work method statement can stand in for it if it holds everything the plan would.
   • Crystalline silica training, nationally accredited or approved by the regulator, with records kept while the worker does the work and for 5 years after they leave the business.
   • Air monitoring, and a report to the regulator as soon as reasonably practicable, and no more than 14 days, after receiving any result above the exposure standard, even if workers wore well-fitted respiratory protection.
   • Health monitoring for workers doing the high risk processing, carried out or supervised by a medical practitioner experienced in health monitoring.

What the controls look like on concrete work