Controlling construction dust and silica

In short

Cutting, drilling, grinding and chasing concrete, brick, block, stone and mortar creates fine silica dust that can cause lung cancer, silicosis and chronic obstructive pulmonary disease (COPD). Under COSHH you must assess the risk and prevent or adequately control exposure. The workplace exposure limit for respirable crystalline silica is 0.1 mg/m³ averaged over 8 hours, and exposure should be kept as low as reasonably practicable. Reduce the dust first, then use water or on-tool extraction, adding face-fit tested RPE where needed.

Example

cutting kerbs on a driveway

Jade runs a four-person landscaping firm. On a driveway job, Kyle was cutting kerbs and block paving dry with a cut-off saw, and dust drifted over the next garden. Jade stopped the cutting and talked it through with the team. They ordered some blocks cut to size, used a block splitter for straight cuts and fitted water suppression to the saw. Everyone cutting wore a face-fit tested FFP3 mask. Kyle grumbled about shaving every morning, but the dust cloud had gone.

An illustrative example, not a real case.

What the law says

HSE says silica is the biggest risk to construction workers after asbestos. HSE-commissioned estimates found it caused over 500 construction worker deaths in 2005.

Assess the risks before work starts, and record the significant findings if you employ 5 or more people (COSHH, regulation 6).
Prevent exposure or, where that is not reasonably practicable, control it adequately. Control is only adequate if the workplace exposure limit is not exceeded (regulation 7).
The limit for respirable crystalline silica is 0.1 mg/m³ averaged over 8 hours (EH40/2005). EH40 marks silica dust made by work as a carcinogen, so keep exposure as low as reasonably practicable.
Maintain controls. On-tool extraction needs a thorough examination and test at least every 14 months, with records kept for 5 years (regulation 9).
Give workers information, instruction and training (regulation 12).

Control the dust in this order

01
Stop or reduce it
Design out cuts, order materials cut to size, or use a less powerful tool such as a block splitter.
02
Water
Use enough water, at the right rate, for the whole time the work is done. Wetting the material first does not work.
03
On-tool extraction
Fit extraction to the tool with an H (high) or M (medium) class unit, not a general vacuum.
04
RPE as well
Where water or extraction do not reduce exposure enough, add RPE with an assigned protection factor (APF) of 20.

Common tasks and controls

Cutting kerbs, blocks and paving with a cut-off saw
Control the dust with
Water suppression, and RPE with an APF of 20
Chasing concrete or raking out mortar
Control the dust with
On-tool extraction with an H or M class unit, and RPE with an APF of 20
Drilling holes as the main activity
Control the dust with
On-tool extraction with an H or M class unit, and RPE with an APF of 20
Sanding plasterboard joints
Control the dust with
On-tool extraction with an H, M or L class unit
Cleaning up dust and debris
Control the dust with
Damping down, or vacuum attachments on an H or M class unit, rather than dry sweeping

Task	Control the dust with
Cutting kerbs, blocks and paving with a cut-off saw	Water suppression, and RPE with an APF of 20
Chasing concrete or raking out mortar	On-tool extraction with an H or M class unit, and RPE with an APF of 20
Drilling holes as the main activity	On-tool extraction with an H or M class unit, and RPE with an APF of 20
Sanding plasterboard joints	On-tool extraction with an H, M or L class unit
Cleaning up dust and debris	Damping down, or vacuum attachments on an H or M class unit, rather than dry sweeping

Note: Taken from HSE's Construction dust information sheet (CIS36), which covers more tasks.

Masks and health checks

RPE is the last line of protection, not the first.
Tight-fitting masks need a face fit test for each wearer, who needs to be clean shaven where the mask seals.
Where workers are regularly exposed to silica dust and silicosis could reasonably develop, health surveillance must be provided (COSHH, regulation 11).
An occupational health professional should run it, with a questionnaire, lung function tests and chest x-rays. Keep health records for at least 40 years (regulation 11).

Common questions

What is the workplace exposure limit for silica?

For respirable crystalline silica it is 0.1 mg/m³ averaged over 8 hours (EH40/2005). It is a maximum, not a target.

What mask do I need for cutting concrete?

HSE's general level for construction dust is an APF of 20, such as an FFP3 disposable mask or a half mask with a P3 filter. It needs a face fit test, and should be used with water or extraction, not instead of them.

Can I use an ordinary vacuum for construction dust?

No. HSE says use an extraction unit of the right class, H (high) or M (medium), or L (low) for some tasks such as sanding plasterboard, not a general commercial vacuum.

Do workers exposed to silica need health checks?

Yes, if they are regularly exposed and silicosis could reasonably develop: COSHH requires health surveillance (regulation 11). HSE guidance G404 describes a suitable scheme.

How NXT-HSE can help

NXT-HSE can help you assess dust risks, set out the right controls in your RAMS and COSHH assessments, and check that the controls work on site.

Sources

Sources checked 27 September 2026 against current Health and Safety Executive guidance and legislation. This guide is general information, not legal advice; your legal duties stay with your business.

Construction dust and silica: controlling the risk.