Manufacturing & Engineering

Control respirable crystalline silica (RCS) dust in the workplace

How to identify and control silica dust exposure in your workplace. Covers COSHH assessment for RCS, the workplace exposure limit (0.1 mg/m3), engineering controls, RPE selection, health surveillance and air monitoring. Silica dust is a current HSE enforcement priority.

UK-wide
Guide summary

You must control silica dust if your workers cut, grind or drill materials like concrete, brick or stone. Use water suppression or extraction systems to reduce dust. Provide FFP3 masks where needed. You must also arrange health checks and air monitoring for workers regularly exposed to silica dust.

  • Control dust from cutting concrete, brick or stone
  • Use water suppression or extraction systems first
  • Provide FFP3 masks if engineering controls not enough
  • Keep dust below 0.1 mg/m³ (8-hour average)
  • Arrange health checks for regularly exposed workers
  • Do air monitoring to check dust levels
  • HSE is targeting sites with poor dust control
  • Failure can lead to prohibition notices or prosecution
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UK-wide

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Why silica dust control is critical

Respirable crystalline silica (RCS) dust is generated when workers cut, grind, drill or demolish materials containing silica, including concrete, sandstone, brick, mortar and engineered stone. When inhaled, fine silica particles cause irreversible lung damage including silicosis, lung cancer and chronic obstructive pulmonary disease (COPD).

Occupational lung disease is a current HSE enforcement priority. HSE inspectors are actively targeting construction sites and manufacturing premises where silica dust is not adequately controlled. Enforcement action including prohibition notices and prosecution is being taken against businesses that fail to protect workers.

This guide explains your legal duties and the practical steps to control silica dust exposure.

Who needs to act

You must control silica dust if your workers carry out any of these activities:

  • Cutting or grinding concrete, paving slabs, kerbs or blocks
  • Drilling into concrete, brick or stone
  • Demolishing concrete or masonry structures
  • Chasing walls for cables or pipes
  • Angle grinding stone, concrete or mortar
  • Tunnelling or mining through rock containing quartz
  • Working with engineered stone (very high silica content, typically 90%+)
  • Sand blasting or shot blasting (where silica-containing abrasives are used)
  • Manufacturing bricks, tiles, pottery or glass
  • Quarrying sandstone, granite or other silica-bearing rock

If any of these activities take place in your workplace, you have a legal duty under COSHH 2002 to assess and control the risk from silica dust.

How to carry out a COSHH assessment for silica dust

Your COSHH assessment for RCS must be specific to each task that generates silica dust. A generic assessment covering all activities is not sufficient.

  1. 1

    1. Identify all silica-generating tasks

    Walk through your workplace and list every activity that cuts, grinds, drills or disturbs materials containing silica. Include tasks carried out by contractors on your site. Note the materials being worked on, the tools used, the duration and frequency of each task, and the number of workers involved.

  2. 2

    2. Assess the level of exposure

    Consider how much dust each task generates. Factors include the silica content of the material (engineered stone is 90%+ silica, concrete is 25-70%, brick is 10-30%), the energy of the process (cutting generates more than drilling), whether the work is indoors or outdoors, and the duration of exposure. If you cannot be confident exposure is below the WEL without measurement, arrange air monitoring.

  3. 3

    3. Select engineering controls

    Apply the hierarchy of controls. Your first choices must be engineering controls: water suppression for cutting and grinding, on-tool extraction for drilling and chasing, local exhaust ventilation (LEV) for enclosed processes. These must be in place before considering RPE.

  4. 4

    4. Select appropriate RPE

    Where engineering controls alone cannot reduce exposure below the WEL, provide RPE as an additional control. For silica dust, the minimum standard is an FFP3 disposable mask (Assigned Protection Factor 20) or a powered air-purifying respirator. Half-face masks with P3 filters are also acceptable. All tight-fitting RPE must be face-fit tested for each wearer.

  5. 5

    5. Set up health surveillance

    Workers regularly exposed to silica dust must be enrolled in a health surveillance programme. This includes an initial health questionnaire and lung function baseline test before first exposure, then periodic lung function testing at intervals determined by your occupational health provider. Records must be kept for 40 years.

  6. 6

    6. Arrange air monitoring

    Commission air monitoring to confirm your controls are keeping exposure below the WEL of 0.1 mg/m3 (8-hour TWA). Use the gravimetric sampling method with a cyclone sampler. Monitor during representative work activities. Repeat monitoring when processes, materials or controls change.

  7. 7

    7. Train your workers

    Provide training on the health risks from silica dust, how to use controls correctly (including water suppression and LEV), how to wear and fit check RPE, the importance of good housekeeping (never dry sweep silica dust), and what to do if controls fail or are not working.

  8. 8

    8. Record and review

    Document your COSHH assessment, including the controls selected and the reasons. Review the assessment regularly and whenever there is reason to suspect it is no longer valid, such as after air monitoring results, changes to work methods, or new equipment.

Engineering controls in detail

Engineering controls are the most effective way to reduce silica dust exposure. They protect all workers in the area, not just the individual using the tool.

Water suppression

Applying water to the cutting or grinding point captures dust at source. This is the single most effective control for most construction tasks. Water suppression can reduce dust levels by 80-95% compared to dry cutting.

  • Use tools with built-in water feeds wherever possible
  • Ensure adequate water flow throughout the task
  • Manage slurry run-off appropriately
  • Do not allow slurry to dry out and become a secondary dust source

On-tool extraction

Dust extraction fitted directly to the tool captures dust at the point of generation. Effective for drilling, chasing and some grinding tasks. The extraction unit must have an appropriate filter (typically a class M or H filter for fine dust).

Local exhaust ventilation (LEV)

For fixed workstations, such as in stone workshops or manufacturing, LEV draws contaminated air away from the worker's breathing zone. LEV systems must be:

  • Designed by a competent person for the specific application
  • Thoroughly examined and tested at least every 14 months under COSHH Regulation 9
  • Maintained in efficient working order

RPE selection for silica dust

RPE is an additional control measure, used alongside engineering controls. It must never be the only control unless the task is very short duration and infrequent.

For silica dust specifically:

  • FFP2 masks are not adequate for silica dust when exposure is likely to approach or exceed the WEL
  • FFP3 masks (APF 20) are the minimum for silica dust exposure
  • Powered air-purifying respirators with P3 filters should be considered for prolonged tasks
  • Workers with facial hair that prevents a seal must use loose-fitting powered respirators
  • All tight-fitting RPE must be face-fit tested before first use

Health surveillance

Workers regularly exposed to silica dust must receive health surveillance to detect early signs of lung disease:

Housekeeping

Poor housekeeping is one of the most common silica dust control failures identified by HSE inspectors:

  • Never dry sweep silica dust - this creates a secondary dust cloud
  • Use an industrial vacuum with an H-class filter (HEPA) or damp cleaning methods
  • Clean up dust and slurry before it dries
  • Do not use compressed air to blow down dusty surfaces or clothing
  • Provide designated clean areas for eating and drinking, away from dusty work zones
  • Ensure workers can wash before eating or drinking

Common enforcement failures

HSE inspectors consistently find these failings on site:

  • Dry cutting concrete or stone with no dust suppression - this is the single most cited silica dust violation
  • No COSHH assessment for silica-generating tasks
  • RPE provided as sole control without engineering controls being considered first
  • RPE not fit tested or wrong type used (FFP2 instead of FFP3)
  • LEV not examined and tested within the 14-month statutory interval
  • No health surveillance for regularly exposed workers
  • Dry sweeping dust or using compressed air for cleaning

HSE can issue immediate prohibition notices for uncontrolled silica dust exposure. Fee for Intervention charges apply for material breaches.

Construction & Property Requirement

Construction sites - additional requirements

Construction sites generate the highest levels of silica dust exposure. Principal contractors and contractors have specific duties:

  • The construction phase plan should address silica dust control for all relevant tasks
  • Coordination between trades is essential - cutting in one area can expose workers nearby
  • Consider scheduling dusty tasks when fewer workers are present
  • Ensure welfare facilities allow workers to wash silica dust from skin before breaks
  • Subcontractors' workers must receive the same level of protection as your own employees

What to do next

  1. Audit your workplace for all silica-generating tasks
  2. Conduct or update COSHH assessments for each task
  3. Implement engineering controls - prioritise water suppression and on-tool extraction
  4. Provide appropriate RPE (minimum FFP3) and arrange fit testing
  5. Set up health surveillance for regularly exposed workers
  6. Commission air monitoring to verify controls are effective
  7. Train all affected workers on the risks and controls

Official guidance on GOV.UK and HSE