How do I protect myself from silica dust when cutting brick, concrete or stone?
Why masonry dust is a different problem from wood dust, the two controls that actually work — water and on-tool extraction — and what to do about the dust that remains, including protecting everyone else in the house.
- Difficulty
- intermediate
- Time
- 25 min
- Read
- 5 min
- Safety
- warning
Short answer
Cut wet, or use an on-tool shroud connected to an M-class extractor, and wear an FFP3 mask on top of either. Work outdoors and upwind, keep everyone else away, and never dry-cut masonry indoors. Clean up by vacuuming or damping down, never by sweeping.
Brick, block, concrete, mortar, paving, sandstone, tile and fibre cement all contain crystalline silica, and cutting or grinding them releases a fraction fine enough to reach deep into the lung. It is invisible, it is odourless, and the dose from a few minutes of dry cutting with a disc cutter is very large. This is one of the genuinely serious health hazards a householder can meet.
Safety
What you'll need
- Water supply and a way to feed it to the cut, or an on-tool dust shroud
- M-class or fine-filter extractor, if cutting dry with extraction
- FFP3 mask, correctly fitted
- Sealed goggles and hearing protection
- Overalls or clothes you will change out of
Step by step
- Ask whether you have to cut it at all.Ordered-to-size materials, a merchant's cutting service, snapping with a block splitter or a tile cutter, and hand-cutting with a bolster all avoid the dust entirely. A hydraulic block splitter hired for a day produces no dust at all and is often quicker than a grinder for a paving job.
- Cut outdoors, upwind, and away from everyone.Never dry-cut masonry indoors or in a garage. Position yourself so the wind carries the dust away, close the windows and doors of the house, and keep other people, children and pets well clear and indoors.
- Use water suppression if you can.A wet-cut saw, or a water feed to the blade, or a bottle sprayer directed at the cut line by a helper. Water knocks the fine fraction down at the point it is created and is the most effective single control. Use a diamond blade rated for wet cutting and an RCD-protected supply, and never use water with an electric tool not designed for it.
- Or use on-tool extraction.A dust shroud fitted to the grinder or the cutter, connected to an M-class or fine-filter extractor with adequate airflow. Fitted and used properly it removes a very large proportion of the dust. A household vacuum is not adequate and will be destroyed by the dust.
- Wear an FFP3 mask as well.Neither water nor extraction removes everything, and what remains is the respirable fraction. FFP3, fitted and fit-checked, with no facial hair on the sealing edge. This is not the job for an FFP2 or a nuisance mask.
- Add eye and hearing protection.Sealed goggles rather than glasses, because masonry dust goes round a frame, and a face shield over them for grinding. Disc cutters and grinders are loud enough to require hearing protection every time.
- Keep the cut short and the tool right.A sharp diamond blade in good condition cuts faster and produces less dust than a worn one. Cutting in several shallow passes rather than one deep plunge is easier on the tool and produces less dust in the air at once.
- Clean up wet or with a vacuum.Damp down the area and shovel or vacuum with an M-class machine. Never sweep or use a leaf blower — both put hours of settled dust straight back into the air, and this is where a large share of total exposure comes from.
- Deal with your clothes and yourself.Change outside, do not shake dusty clothes out indoors, wash them separately, and wash your hands and face before eating. Dust carried indoors on clothing exposes everyone else in the house afterwards.
- Know what you must not cut.Engineered quartz and some composite worktops have a very high crystalline silica content and cutting them has caused severe silicosis in fabricators. That is specialist work with proper controls, not a householder job — have it templated and cut by a fabricator.
Tips
- A block splitter or a paving splitter, hired for a day, cuts blocks and slabs with no dust, no noise and no power. For a patio or a wall it is often the better tool as well as the safer one.
- Chasing walls for cables or pipes is a high-exposure job because it is done indoors. A chaser with a dust shroud and an M-class extractor is what makes it acceptable, and it is worth hiring one rather than using a grinder.
- Old artex, insulation board, cement sheet, floor tiles and pipe lagging in a pre-2000 building may contain asbestos. If you are not certain what you are cutting, stop and get it identified — the controls for silica are not the controls for asbestos.
- Tell your neighbours before a day of cutting. Dust travels, and washing on a line comes in filthy.
Common mistakes
- Dry-cutting masonry with an angle grinder and no controls — It produces extremely high concentrations of respirable silica within seconds. The dust cloud is visible; the harmful fraction is not, and it stays airborne long after the visible cloud has gone.
- Wearing a mask instead of using water or extraction — A mask is the last line of defence and it depends entirely on a perfect seal for the whole duration. Controlling the dust at the source is what actually reduces the dose.
- Sweeping up afterwards — Sweeping re-suspends settled dust in enormous quantities, often producing a higher exposure than the cutting did, and it is usually done without a mask because the noisy part is over.
- Cutting in the garage with the door open — The dust stays in the space and settles on everything, and the garage is often attached to the house. Masonry cutting happens outdoors.
Questions people ask
Is a bit of brick dust really that harmful?
The health risk is dose-related and cumulative, so one afternoon is not the same as a career. But dry-cutting with a disc cutter generates concentrations far above occupational limits within a very short time, and the damage does not reverse — which is why the controls are worth the trouble even for occasional work.
Can I cut wet with an ordinary angle grinder?
Not safely. Introducing water to a mains-powered tool that is not designed for it is an electrocution risk. Use a tool designed for wet cutting on an RCD-protected supply, or use dry cutting with an on-tool shroud and extraction instead.
What about drilling rather than cutting?
Drilling produces far less dust than cutting, but SDS drilling into concrete still produces respirable dust, especially overhead. Use a dust extraction attachment or a shroud, wear an FFP3 mask, and vacuum rather than sweep.