A dust cloud from a concrete saw is a warning that the job needs attention. The absence of a visible cloud is not proof that exposure is safe. Respirable crystalline silica, or RCS, includes particles small enough to reach deep into the lungs. Employers need to prevent exposure where possible and adequately control what remains. This guide focuses on everyday construction and maintenance tasks in Great Britain, where COSHH applies; Northern Ireland has separate regulations.
Start with the material and the task
Concrete, mortar, bricks and many natural stones contain crystalline silica. Cutting, drilling, chasing and grinding them can release respirable dust. Significant exposure can cause silicosis, and RCS exposure can also cause lung cancer and chronic obstructive pulmonary disease. Workers may suffer permanent damage before symptoms become obvious.
Assess the actual job: what is being worked, which tool will disturb it, how long and how often the work happens, where dust can travel and who else can breathe it. Outdoor work is not automatically low risk. A saw operating beside an open doorway can expose both the operator and people inside.
For a North East maintenance contractor, repeated short jobs across several properties should be considered together. Five minutes at one address does not describe a worker’s exposure across a day of chasing walls or drilling concrete. Include apprentices, other trades, occupants and the person sent to clean up.
Remove unnecessary dust-generating work
The most useful control may be a planning decision. Order materials to a suitable size, adjust the layout to reduce cuts or arrange controlled off-site preparation. Consider a block splitter where it can achieve the result, or an installation method that avoids chasing. These choices should be settled before tools arrive and the programme becomes difficult to change.
A contractor replacing paving outside a busy shop could first plan a layout with fewer cut pieces and locate unavoidable cutting away from the entrance. The supervisor should agree the method and pedestrian arrangements with the occupier. Moving the saw a few metres while leaving dust blowing towards the queue is not a complete solution.
Where work remains necessary, record the controls for that task rather than copying a general statement that masks will be worn. A large floor-grinding job, occasional drilled fixing and mortar-raking operation need different equipment and exposure decisions.
Choose suppression or extraction for the work
For cutting paving, blocks and kerbs, HSE identifies water suppression or suitable specially adapted on-tool extraction, alongside respiratory protection. Water must reach the cutting point effectively throughout the operation. Wetting a slab before cutting is not equivalent to a working suppression system. Check supply, jets and the equipment’s suitability for wet use.
Chasing concrete and raking mortar typically need a purpose-designed tool and capturing hood connected to suitable extraction. Treat the tool, hood, hose and extractor as one system. Gaps at the hood, loose connections or a blocked hose can undermine the arrangement even when the motor is running.
Use a suitable H- or M-class extraction unit for these silica tasks, with the airflow and capacity the job requires. A household vacuum, or a general vacuum fitted with a HEPA filter, is not an equivalent system. Obtain compatible equipment and supplier instructions; do not assume every extractor works with every tool.
For drilling, assess the number and size of holes and the material, and select a suitable dust-capture arrangement for that operation. Check the relevant HSE task guidance and tool instructions rather than extending a cutting method to drilling without review.
HSE: cutting paving blocks, kerbs and flags ↗ · HSE: on-tool extraction, CIS69 ↗
Specify respiratory protection for the remaining exposure
For cut-off saw work on paving and for concrete chasing or mortar raking, HSE specifies RPE with an assigned protection factor of 20 alongside the engineering controls. Examples include an FFP3 disposable mask or a half mask with a P3 filter. This is task-specific guidance, not a reason to treat any dust mask as suitable for every activity.
Tight-fitting RPE requires face-fit testing for the wearer and model, and a seal free from interfering facial hair. Check compatibility with eye protection, hearing protection and other equipment. Longer or demanding work may need a suitable powered alternative. Workers must know how to use, check, store and replace their protection.
If the water supply stops or the extraction fails, stop the dust-generating work and restore the control. Wearing the planned respirator does not turn an uncontrolled process into the agreed safe method.
HSE: chasing concrete and raking mortar ↗ · Related guide: face-fit testing →
Does the method statement match the equipment on site?
HR + SAFETY can help review silica-generating tasks, equipment arrangements and supervisor checks so the planned controls can be used in practice.
Discuss your silica dust controlsInclude cleanup and the next trade
Dust left on floors, tools and ledges can become airborne again. Avoid dry sweeping where possible; plan suitable vacuum collection for fine dust and damp methods for appropriate debris. Provide the required equipment and waste containers before the job begins, rather than expecting the cleaner to solve the exposure problem afterwards.
Define who can enter the work area and when. Use suitable separation and coordination where other trades or occupants remain nearby. Check whether dust can pass through doors, ventilation paths or gaps into occupied rooms. Keep people with relevant health vulnerabilities away from exposure and address their needs in the work arrangements.
Manage wet slurry too: contain and remove it safely before it dries into another dust source, while controlling slip and electrical risks. The work is not complete simply because the last cut has been made.
Check controls and decide on health surveillance
Supervisors should observe the method in use and respond to damaged hoods, low airflow warnings, blocked water jets and poor respirator fit. Follow planned equipment checks, maintenance and the applicable examination requirements for extraction. A service record does not demonstrate that the hose is connected correctly today.
Consider competent exposure assessment where you cannot establish that controls are adequate. Do not use visible dust alone as your measure. If the task, material, duration or work area changes, revisit the assessment rather than continuing under an old method statement.
HSE’s G404 says health surveillance must be provided where workers are regularly exposed to RCS and there is a reasonable likelihood that silicosis may develop. Involve an occupational health professional with relevant competence to determine the scheme. Surveillance does not replace exposure controls, and findings must feed back into risk management.
HSE: RCS health surveillance, G404 ↗ · Related guide: managing local exhaust ventilation →
Silica task checklist before work starts
- Identify silica-containing materials and everyone potentially exposed.
- Reduce cutting, chasing or drilling through design and work planning.
- Select a task-matched water or extraction system and check it works.
- Specify any required RPE, fit testing, training and compatible PPE.
- Agree segregation, access, waste collection and safe cleanup.
- Give workers clear stop-work instructions for control failure.
- Arrange supervision, maintenance and exposure advice where needed.
- Record the health surveillance decision and review it when circumstances change.
Effective silica dust control is a complete work method: reduce the dust created, capture or suppress it at source, protect against remaining exposure and leave the area safe for the next person.
This guide provides general information for UK employers. It is not legal advice and should not replace advice based on the facts of a specific matter.