A polished floor is made at the top of the slab.

What the regulators mean by the work

SafeWork NSW’s code of practice describes concrete and masonry products as being modified by cutting, drilling and grinding, with specialised techniques, tools and equipment. The same code describes the grinding tools in particular: mobile or handheld machines that strip coatings, glues and paints and also take away part of the concrete itself, to prepare a surface or to finish it, polishing among the finishes. That is the machine working the top of the slab.

The regulators agree on what comes off it. WorkSafe Victoria says crystalline silica dust is generated when these materials are mechanically processed, and gives cutting and grinding as its examples. Workplace Health and Safety Queensland says handheld grinders used to smooth or cut concrete, masonry or other material holding silica can generate respirable crystalline silica dust.

Three Safe Work Australia statements say what kind of work that makes it. Concrete is among the common crystalline silica substances. Grinding and polishing are among the mechanical processes the exposure standard page lists as producing the dust. And the model Code of Practice says processing a crystalline silica substance must be controlled, with no business to carry out, direct or allow it otherwise. Read side by side, the three put a floor grinder’s pass under the duty to control, though no single one of them says it in a line about floors.

Why the duty exists is the regulators’ plain warning. WorkSafe Victoria describes silicosis as a lung disease that cannot be reversed or cured, keeps progressing, and can end in disability or death. The three state pages are written for the people doing the work, and nothing here is a set of steps for doing it.

Whose duty it is

The duty sits on the business doing the work. SafeWork NSW’s code says it is intended to be read by a person conducting a business or undertaking, the PCBU. WorkSafe Victoria puts it on the employer: employers must manage the risk from crystalline silica using the hierarchy of control set out in Part 4.1, hazardous substances, of the Victorian OHS Regulations. The hierarchy is the order in which controls are chosen, and the controls each regulator names for the grinder itself are set out below.

Wet grinding and its slurry

SafeWork NSW’s code says concrete grinding can be done wet or dry, the choice depending on the outcome required and on environmental factors.

WorkSafe Victoria names on-tool water suppression as one of the most effective ways to cut exposure to the dust. It also names the cost of the method: the slurry has to be managed so that it does not dry out. Dried slurry is simply the dust again, and Workplace Health and Safety Queensland says the same in its own words: slurry is to be cleared before it dries and puts silica back into the air.

Queensland’s page is specific about the tool and the place. It covers handheld grinders, and it says a grinder with an integrated water feed to the grinding surface may be used to hold the dust down while cutting, grinding or polishing silica-containing material outdoors. Its list of engineering controls, of which one must be used, marks the integrated water delivery system as outdoor use only. The three are written for different tools and settings: each stands beside its own regulator here, not merged.

Dry grinding, with the dust taken at the tool

The dry method relies on capture at the machine. SafeWork NSW’s code says dry grinding uses local ventilation on the tool, and, among the control measures it lists for grinding safety, that the tools, handheld or mobile ride-on, should be electric with dust extraction built in.

WorkSafe Victoria counts extraction fitted to the tool among the effective ways to cut exposure, because it takes the dust away from the source as it is produced. On the vacuum, Victoria says the extraction has to run to a vacuum rated Dust Class M or H, or to some other system that captures any dust the power tool makes. Workplace Health and Safety Queensland names the same two classes and ties them to the standard AS/NZS 60335.2.69, as the rating a dust collection system can carry for a handheld grinder.

Victoria sums the two methods in one sentence about every silica-containing material: effective dust controls, on-tool water suppression or on-tool extraction among them, are needed for cutting, grinding, crushing, drilling or demolishing.

Clearing the floor without dry sweeping

The pass is not over when the machine stops, and the regulators put cleaning inside the work. WorkSafe Victoria wants the work area cleaned once each job is done, so that no silica dust builds up on plant, equipment, working surfaces or the floor. The cleaning itself must not spread dust. Its examples are a HEPA-filtered vacuum of Dust Class M or H, low-pressure hosing, mopping, squeegeeing and wet wiping. Victoria rules out three methods by name, compressed air, dry sweeping and high-pressure water, because each is likely to raise airborne dust.

SafeWork NSW’s code lists the same pairing under what PCBUs should ensure: an M or H class vacuum cleaner for dry dust on tools, equipment, floors, walls and other surfaces, and low pressure water or wet sweeping for wet slurry. Among its control measures for dust, it lists ensuring the operator is responsible for clean-up, removal and disposal of the dust, slurry included, by a safe method after the task.

Breathing protection, as each source places it

SafeWork NSW and WorkSafe Victoria both put the respirator after other controls. SafeWork NSW’s code lists respiratory protective equipment as something used together with the higher-level controls it names. It adds that selecting and providing RPE and PPE is the PCBU’s responsibility and can be settled by a risk assessment.

WorkSafe Victoria’s order is the same: where a risk remains after the controls, the employer has to supply suitable protective equipment, RPE among it. Its page says the equipment needs at least a P2 filter and a fit test for each person. Workplace Health and Safety Queensland attaches a health duty to frequent use: health monitoring must be provided by the PCBU for a worker whose tasks need RPE 30 times or more in 12 months.

The three pages side by side

Each regulator writes for a different reader, and the differences matter more than the overlaps.

New South Wales

A code of practice for the PCBU. It treats wet and dry as a choice made on the outcome and the setting, and lists making the operator responsible for clean-up among its dust controls.

Victoria

A page for the employer, built on the hierarchy of control. It ranks on-tool water suppression among the most effective controls, and it rules out dry sweeping, compressed air and high-pressure water by name.

Queensland

A page for handheld grinders. It limits the integrated water system to outdoor use, rates the dust collection system by class and standard, and links frequent respirator use to health monitoring.

The floor it leaves

A ground and polished slab ends up as a walking surface. The Australian Building Codes Board’s 2020 advisory note on slip resistance for stairways, landings and ramps says that, for slip resistance, DP2 and P2.5.1 are the mandatory requirements within the National Construction Code. It recalls that the 2014 edition of the code required the treads or nosings of a stairway, and for certain buildings the surfaces of ramps and landings, to meet a slip resistance classification when tested to the 2013 edition of AS 4586, the standard for classifying new pedestrian surface materials. The note says that requirement, for stairway treads and nosings and for the ramps and landings of certain buildings, applies to all finishes and surface types, concrete among them.

No rating for any polished finish is given, because none of the pages linked at the foot of this page sets one.

The note names two ways of classifying a surface. The wet pendulum test gives a classification from P0 to P5 and can be run on site or in a laboratory. The oil-wet inclining platform test gives a classification from R9 to R13 and is a laboratory test.

Wet and dry, in the note’s words

The note separates wet from dry when it works out the surface condition expected at the time of construction. A wet surface includes one that is exposed to weather, such as an external stairway, and one that on occasions becomes wet, such as an entry lobby. A dry surface, in the note’s words, is one that is not normally wet or likely to be made wet, other than by an accidental spill or general cleaning.

The same word, wet, has two meanings on this page. For the grinder it is a method, water at the tool. For the floor it is a condition of use, and the note’s examples are an external stairway and an entry lobby.

Where this goes next

The slab’s own numbers, the 1 per cent definition and the 0.05 mg/m³ line, are in the guide to the dust grinding makes. Who the duty reaches in the rest of a house is in the household guide. If an old covering sits above the slab, the asbestos side begins at what is under the old floor. What the pass then leaves the floor as is in the finishes guide, and what it leaves outside the room is in the last guide.