Silica Dust Construction Risks: Health Effects and Controls

Silica dust is a fine dust released when you cut, drill, grind or break materials such as concrete, brick, mortar, stone and tiles, and breathing in the smallest particles can cause serious and sometimes fatal lung disease. The harmful part is called respirable crystalline silica. Because it is controlled under COSHH, employers must prevent or adequately control exposure. This guide explains where the dust comes from, what it does to health, and the controls that work, in line with the HSE silica dust page.

Key takeaways

What silica dust is and where it comes from

Silica, in its crystalline form, is found in many common construction materials. Concrete, brick, mortar, sandstone and some tiles and stone worktops contain it. Soil and sand can contain it too. When these materials are worked on with power tools, fine dust is created, and some of that dust is small enough to travel deep into the lungs. That fraction is called respirable crystalline silica, and it is the part that matters for health.

Typical tasks that create silica dust on site include:

• Cutting paving slabs, kerbs, blocks and bricks with a disc cutter.
• Chasing walls and drilling into concrete or masonry.
• Grinding or sanding concrete and mortar joints.
• Breaking or demolishing masonry and concrete.
• Dry sweeping or using compressed air in areas where this dust has settled.

You cannot judge the danger from how much dust you can see. The finest particles are invisible in normal light, and dust that has settled can be disturbed again and again. Treat any dust from these materials as hazardous.

The health risk

Breathing in respirable crystalline silica can lead to:

• Silicosis. Scarring of the lungs that can cause breathlessness and reduced lung function.
• Lung cancer.
• Chronic obstructive pulmonary disease (COPD). A long-term lung condition that makes breathing difficult.

These conditions usually develop over years, not days, so workers can feel well while damage is building. Once the harm is done, it often cannot be reversed. This long delay is why controls are needed on every dusty task, not only when someone starts coughing.

The legal framework in plain English

Silica dust is a hazardous substance, so it falls under the COSHH regulations. The COSHH basics guide explains the general steps in more detail. For silica, the main ideas are:

• The employer must assess the risk from the dust created by the work.
• The employer must prevent exposure or, where that is not possible, adequately control it.
• Controls must be used, maintained and checked.
• Where appropriate, exposure should be monitored and health surveillance provided.
• Workers must be informed, instructed and trained.

There is a workplace exposure limit for respirable crystalline silica. This guide does not quote it, because it is a figure that should be checked against current HSE guidance. If you need the figure for a task assessment, use the official HSE pages.

Controls that work

COSHH 2002 regulation 7 requires employers to prevent exposure where reasonably practicable and otherwise to control it in order of priority: work processes and engineering controls, control at source, and PPE only if those cannot adequately control exposure. For construction dust, in plain terms: stop the dust being made, then stop it getting into the air, then protect the person (general practice).

1. Avoid or reduce the dust

Ask whether the task is needed in that form. Using materials supplied cut to size, or a method that does not need cutting on site, removes the dust at source.

2. Suppress or capture it at source

• Water suppression. A water-fed cutter or a tool with a water supply keeps dust from getting into the air. Keep the water flowing for the whole task (general practice).
• On-tool extraction. A tool fitted with extraction connected to a suitable dust extractor captures dust as it is created. The extractor needs the right filter and must be emptied and maintained as instructed (general practice).
• Enclosure and location. Doing dusty work in a controlled area, or outdoors where air movement helps, reduces exposure for others.

3. Keep the site clean

• Clean up with a suitable vacuum or by wet methods.
• Do not use dry brushing or compressed air to clear dust, because this puts settled dust back into the air.
• Do not use your clothes as a dust brush, and take care not to carry dust home.

4. Respiratory protective equipment (RPE)

When other controls cannot do enough, RPE is used as the last line of defence (general practice). It has to be the right type for the dust, and tight-fitting masks need to be fit tested for the person wearing them. Facial hair that stops the mask sealing against the skin can make the protection fail. RPE must be worn throughout the task, kept clean, and replaced or maintained as instructed. The PPE guide covers protective equipment more widely.

Silica dust task checklist

Practice check

These questions are original practice items written for this site. They are not official CITB questions and do not predict your result. This site is independent and not affiliated with CSCS or CITB. For the format of the real test, see the operatives test format page.

Question 1. You need to cut a concrete kerb with a disc cutter. Which approach best controls silica dust?

• A. Cut dry and wear a paper dust mask
• B. Use a cutter with water suppression or on-tool extraction, with RPE as a back-up if needed
• C. Cut quickly so less dust is made
• D. Sweep the dust away afterwards with a brush

Correct answer: B. Controlling dust at source with water or extraction comes first, and RPE is the last line of defence.

Question 2. What is the safest way to clear settled dust from a work area after cutting masonry?

• A. Use compressed air
• B. Dry sweep it into a pile
• C. Use a suitable vacuum or wet cleaning methods
• D. Leave it for the next shift

Correct answer: C. Dry sweeping and compressed air put fine dust back into the air where it can be breathed in.

A worked example: cutting kerbs on a paving job

This is an invented illustration, not a real case. Consider a small team laying a paved area. The plan calls for kerbs and slabs to be cut to fit. The task involves a disc cutter, and the material is concrete, which can release respirable crystalline silica.

A sensible supervisor walks through the controls in order before work starts.

1. Can the cutting be avoided? Perhaps some pieces can be ordered to size, which cuts the amount of dust made on site (general practice).
2. What controls the dust at the cutter? A cutter fed with water, or one with on-tool extraction, is set up and checked before the first cut.
3. Who else is nearby? The cutting is done away from other trades, or they are kept clear while it happens.
4. What is the back-up? The assessment names the RPE for the task, and each wearer has been fit tested and is clean shaven where the mask seals.
5. How is the area cleaned? A suitable vacuum or wet methods are used, with no dry sweeping or compressed air.

The operator then checks the water is flowing or the extractor is running at the start, and stops if either fails. Stopping and reporting is the right response, because carrying on dry is exactly the situation the controls are there to prevent.

Common questions on site

• Is it fine if the dust is only light? No. The harmful fraction cannot be seen, so judge the task, not the visible cloud.
• Can I rely on my mask alone? RPE is the last line of defence, so look for water or extraction first.
• Who decides which controls apply? The employer's COSHH assessment, which you can ask to see. The COSHH basics guide explains how it works.
• What if my RPE does not fit? Tell your supervisor, as another type or size may be needed. The PPE guide covers fit and care more widely.

FAQ

Sources

• HSE: Silica dust (construction, cancer)
• HSE: COSHH (Control of Substances Hazardous to Health)
• Legislation.gov.uk: Control of Substances Hazardous to Health Regulations 2002

Independent guide, not affiliated with, authorised by, approved by or endorsed by CSCS or CITB. Last updated 2026-10-08.