Silica dust: health risks, silicosis and how to control exposure

The finest particles, known as respirable crystalline silica (RCS), can penetrate deep into the lungs. Repeated or intense exposure can lead to silicosis and other serious respiratory conditions.

Understanding where silica dust comes from, how it affects health and how exposure can be controlled is essential for protecting workers. Effective prevention may involve changes to working methods, wet dust suppression, local exhaust ventilation, respiratory protective equipment and ongoing checks to ensure control measures remain effective.

What is silica dust?

Silica is a naturally occurring mineral found in many types of rock, sand and clay. It is also present in common construction and manufacturing materials, including bricks, concrete, mortar and ceramics.

Silica occurs in different forms, including crystalline and amorphous silica:

Natural Sources

• Quartz - The most common form of crystalline silica.
• Sand – Most sand, particularly beach and desert sand, consist of quartz.
• Granite – Contains a large amount of quartz.
• Chert and flint – Natural materials composed primarily of micro crystalline quartz.

Manufactured and Processed Materials

• Concrete:  Commonly contains crystalline silica, primarily in the form of quartz.
• Abrasives:  Silica sand-based abrasives are often composed of quartz. Composition can vary by product.
• Engineered stone: Can contain over 90% crystalline silica, posing significant health risks.

Engineered stone has been associated with faster disease progression and higher mortality rates due to its high RCS concentration.

When materials containing crystalline silica are cut, drilled, ground, crushed or otherwise disturbed, fine particles that can be inhaled.

This fine fraction is known as respirable crystalline silica, or RCS. RCS is particularly hazardous because the particles can reach the deepest parts of the respiratory system, where they can trigger inflammation and scarring of lung tissue.

An important point: a material containing silica does not automatically present the same level of risk in every situation. The risk depends on factors such as the material's composition, the work being carried out, the amount of dust generated, the duration of exposure and the effectiveness of the controls in place.

Where is silica dust found?

Silica dust can be generated across a wide range of industries. The risk is particularly relevant wherever materials containing crystalline silica are cut, ground, drilled, crushed or processed.

Common sources include:

• Construction: cutting concrete, drilling masonry, chasing walls, grinding mortar and demolishing structures.
• Stone processing: cutting, shaping, grinding and polishing natural stone.
• Engineered-stone fabrication: manufacturing and finishing kitchen worktops, bathroom surfaces and other products made from engineered stone.
• Quarrying and mining: extracting, crushing and handling rock and mineral materials.
• Foundries: handling silica-containing sand and carrying out processes that disturb sand moulds or castings.
• Ceramics and manufacturing: processing suitable silica-containing raw materials and products.

The amount of respirable dust generated varies considerably between tasks and materials. Dry cutting or grinding can release substantial quantities of airborne dust, while other activities may present lower risks when effective controls are used.

Silica dust is not always visible. Fine particles may remain suspended in the air or spread beyond the immediate work area, potentially exposing colleagues who are not directly carrying out the task.

For this reason, assessing exposure should not rely on whether dust can be seen.

What is silicosis?

Silicosis is a serious lung disease caused by inhaling respirable crystalline silica. When RCS reaches the lungs, it can trigger inflammation and the formation of scar tissue, a process known as fibrosis.

As the disease progresses, this scarring can reduce lung function and make breathing increasingly difficult. The damage is irreversible, and silicosis can be fatal.

There are three commonly recognised forms of silicosis:

• Chronic silicosis: usually develops after many years of exposure, often following prolonged exposure to lower concentrations.
• Accelerated silicosis: can develop over a shorter period following higher levels of exposure.
• Acute silicosis: a less common form associated with very intense exposure, which can develop over months or a few years.

These timeframes are not fixed thresholds. The risk and progression of disease depend on the circumstances of exposure and individual factors.

Silicosis is not the only health concern associated with RCS. Exposure can also contribute to other serious respiratory diseases, including chronic obstructive pulmonary disease (COPD), and is associated with an increased risk of lung cancer.

Preventing exposure is therefore essential, rather than relying on symptoms to identify a problem after damage has occurred.

What are the symptoms of silicosis?

Symptoms can vary depending on the type and severity of silicosis. In some cases, a person may have no obvious symptoms during the early stages of the disease.

Possible symptoms include:

• Persistent cough.
• Shortness of breath, particularly during physical activity.
• Fatigue and reduced exercise tolerance.
• Chest discomfort.

As lung damage progresses, breathing difficulties can become more severe. These symptoms are not specific to silicosis and may occur with other medical conditions. They cannot be used on their own to diagnose the disease. Workers who may have been exposed to silica dust and are concerned about their health should seek advice from an appropriate healthcare professional and explain their occupational exposure history.

Employers should also consider their duties regarding health surveillance for workers who remain at risk, in accordance with the applicable requirements and competent professional advice.

Employer responsibilities: protecting workers from silica dust

Under the Control of Substances Hazardous to Health Regulations (COSHH), employers have a duty to assess and control the risks posed by respirable crystalline silica (RCS). This means taking practical steps to prevent harmful exposure, rather than relying on workers to protect themselves.

Key responsibilities include:

• Assessing the risk: Identify materials and tasks that generate RCS, who may be exposed, and the extent of that exposure.
• Controlling exposure: Prevent exposure where possible and implement effective controls, such as water suppression, local exhaust ventilation (LEV), enclosure or isolation. Provide suitable respiratory protective equipment (RPE) where required.
• Maintaining controls: Ensure equipment is properly maintained, inspected and tested where applicable, and that control measures remain effective.
• Training workers: Explain the risks, safe working procedures, correct use of controls and appropriate cleaning methods.
• Providing health surveillance: Arrange appropriate health surveillance where required, with competent occupational health advice. For workers regularly exposed to RCS where there is a reasonable likelihood of silicosis developing, this is a legal requirement.
• Acting on findings: Review health surveillance results and any concerns raised by workers, investigate potential problems and take further action to reduce exposure where necessary.

Health surveillance is not a substitute for effective exposure control. Silicosis has no cure. Prevention is essential. Lung damage caused by silicosis cannot be reversed, and the disease can continue to progress even after exposure to silica dust has stopped. Health surveillance can help identify signs of disease, but it cannot prevent or reverse established damage. Employers must prioritise effective exposure controls to protect workers before harm occurs.

The absence of symptoms does not mean exposure is safe. Effective dust control should be in place before health problems develop.

Quartz worktops and engineered stone: understanding the risks

Engineered stone has attracted particular attention because some products contain very high proportions of crystalline silica. Cutting, grinding, shaping and polishing these materials can generate hazardous concentrations of respirable dust if exposure is not effectively controlled.

Workers involved in manufacturing, fabricating, installing or modifying quartz worktops and similar surfaces may be at risk. Other people in the workplace can also be exposed when dust escapes into surrounding areas.

The risk depends on the specific material and process, but dry fabrication of high-silica engineered stone is a particular concern.

How can exposure be reduced when processing engineered stone?

Controlling exposure requires a planned approach based on the material, the task and the workplace. Measures may include:

• Selecting lower-silica alternatives where practicable and appropriate.
• Using suitable on-tool water suppression to reduce airborne dust during compatible processes.
• Controlling water-generated mist so that it does not become another route of exposure.
• Using appropriately designed extraction and ventilation where required.
• Providing suitable respiratory protective equipment as part of the overall control strategy.
• Separating dusty activities from other work areas where necessary.
• Maintaining equipment and ensuring workers understand the risks and correct procedures.
• Carrying out appropriate exposure assessment and health surveillance.

Wet working does not automatically eliminate exposure, and water suppression must be properly designed, operated and maintained. Equally, a mask should not be treated as a substitute for effective process controls.

Employers working with engineered stone should consult the latest Health and Safety Executive guidance, including its specific guidance for stone workers and engineered-stone fabrication.

How can silica dust exposure be controlled?

There is no single control measure suitable for every silica-generating task. The appropriate approach depends on the material, the process, the amount of dust generated and the working environment.

Under the Control of Substances Hazardous to Health (COSHH) Regulations, employers must assess risks to their staff and the working area from hazardous substances and prevent exposure where reasonably practicable or adequately control it where prevention is not reasonably practicable.

The following measures may form part of an effective silica dust control strategy.

1. Reduce dust generation at source

• Consider whether the work can be changed to reduce the amount of dust created in the first place.
• Examples include using pre-cut materials, changing the manufacturing method or selecting a suitable alternative material with a lower silica content.
• Where the task cannot be eliminated or changed, the next priority is to control the dust released by the process.

2. Use wet dust suppression

• Water suppression can reduce airborne dust during suitable operations, including some cutting, drilling and grinding tasks.
• Water is applied at or close to the point where dust is generated, helping to prevent particles from becoming airborne.
• However, effective control depends on adequate water delivery, correct positioning and a method appropriate to the equipment and process. Water may also create contaminated slurry or airborne mist, both of which need to be managed safely.
• Wet suppression is not suitable for every application, particularly where water could introduce other hazards or damage the process.

3. Use local exhaust ventilation and dust extraction

• Local exhaust ventilation (LEV) is designed to capture airborne contaminants close to the point where they are generated, before they spread into the surrounding workplace.
• Depending on the application, this may involve on-tool extraction, an enclosed process, a capture hood or a purpose-designed industrial extraction and filtration system.
• System performance depends on appropriate design, positioning, airflow, filtration and maintenance. An extraction system that is poorly matched to the process or inadequately maintained may not provide effective control.
• The suitability of a system should be assessed against the specific task and dust characteristics, rather than assuming that any vacuum or extraction unit will be adequate.
• LEV should also be examined, tested and maintained in line with applicable requirements.

4. Consider enclosure and separation

• Enclosing a dusty process or separating it from other activities can help prevent contaminants from spreading throughout a workplace.
• The approach will depend on the machinery, process and working environment. Where complete enclosure is not practical, partial enclosure, appropriate ventilation and restricted access may help reduce exposure to other workers.
• It is important to consider everyone who could be affected, not just the person operating the tool or machine.

5. Use suitable respiratory protective equipment

• Respiratory protective equipment (RPE) may be required where other measures do not adequately control exposure, and for certain tasks as part of the specified control arrangements.
• The type of RPE must be suitable for the hazard and the level of protection required. Selection should be based on a proper risk assessment and relevant guidance.
• Where tight-fitting RPE is used, face-fit testing is necessary to check that the selected mask fits the individual wearer. Workers also need appropriate training, instruction, maintenance and supervision.
• RPE should be considered within a wider control strategy, not as a reason to tolerate avoidable airborne dust.

6. Clean safely and maintain control measures

• Dust can accumulate on machinery, floors, work surfaces, clothing and other equipment. Poor cleaning practices can disturb settled material and release particles back into the air.
• Dry sweeping and the use of compressed air can create additional airborne dust and should not be used where they would expose workers to hazardous dust.
• Depending on the task and risk assessment, suitable methods may include an appropriately specified industrial vacuum or wet cleaning. The equipment must be suitable for the dust being collected.
• Extraction systems, water-suppression equipment and other controls should be inspected and maintained so that their performance does not deteriorate over time.

7. Assess exposure and train workers

• Employers should assess the risk from each relevant process and ensure that control measures are appropriate and effective.
• Depending on the circumstances, this may involve workplace exposure monitoring, checks on engineering controls, health surveillance and specialist occupational hygiene advice.
• Workers should understand which materials and tasks create RCS, how the controls are intended to work, what to do if equipment fails and how to report concerns.
• Training and supervision help ensure that controls are used consistently and that problems are identified before they lead to harmful exposure.

What is the UK workplace exposure limit for silica dust?

In Great Britain, the workplace exposure limit (WEL) for respirable crystalline silica is 0.1 mg/m³, averaged over an eight-hour reference period.

This is a legal exposure limit, not a guarantee that exposure below it is completely safe. Employers must still apply the principles of good control practice and take appropriate action to prevent or adequately control exposure under COSHH.

The level of control required depends on the process and circumstances. High-dust activities may require multiple measures working together, and exposure should not be judged by visible dust alone.

Employers should consult the latest HSE guidance and the current EH40 Workplace Exposure Limits publication when assessing their obligations.

How can industrial extraction help control silica dust?

Industrial extraction and filtration can play an important role in controlling silica dust where the process and risk assessment identify local exhaust ventilation as an appropriate measure.

The aim is to capture dust as close as possible to its source, limit its spread and filter the extracted air using equipment suitable for the application.

A properly designed solution takes account of the material being processed, the dust-generating activity, the required capture method, airflow, filtration, waste handling and the operating environment.

Performance also depends on installation, commissioning, maintenance and regular checks. Extraction should be considered alongside other relevant controls, which may include wet suppression, enclosure, safe cleaning procedures and respiratory protective equipment.

Nederman works with industrial customers to assess airborne contaminant challenges and develop extraction and filtration solutions suited to their processes. The appropriate approach will depend on the specific application and the wider measures required to control exposure.

For organisations reviewing silica dust risks, understanding the process and the controls already in place is a sensible starting point.

Frequently asked questions about silica dust

Is silica dust always visible?

No. Some dust particles are too small to see under normal lighting conditions and can remain airborne or spread beyond the immediate work area. The absence of visible dust does not demonstrate that exposure is adequately controlled.

Can one exposure to silica dust cause silicosis?

Silicosis is generally associated with cumulative exposure, but very intense exposure can lead to acute silicosis over a relatively short period. A single exposure cannot be assessed reliably without knowing the circumstances, and avoiding further exposure is important. Anyone concerned about a significant exposure should seek appropriate professional advice.

Is silicosis curable?

There is currently no cure that reverses the lung scarring caused by silicosis. Medical care may help manage symptoms and complications, but prevention through effective exposure control is essential.

Does wearing a mask make silica dust safe?

No. RPE can be an important part of protecting workers, but it must be suitable, correctly fitted where required, maintained and used properly. It should be combined with appropriate measures to reduce or control dust at source.

Is wet suppression better than extraction?

Neither method is universally better. Their effectiveness depends on the task, material, equipment and working conditions. Wet suppression may be effective for certain cutting or grinding activities, while LEV may be more suitable for other processes. Some tasks require a combination of controls, including RPE.

What should an employer do if workers may be exposed to silica dust?

The employer should assess the risks, prevent exposure where reasonably practicable or adequately control it, provide appropriate information and training, and ensure that control measures remain effective. The HSE provides task-specific guidance to help employers determine suitable arrangements.

Further guidance on silica dust

For authoritative information about silica dust and workplace exposure, consult:

• Health and Safety Executive (HSE): Control of exposure to silica dust
• HSE: Construction silica and COSHH guidance
• HSE Books: Controlling exposure to stone dust (HSG201)

These resources provide further information on workplace risks, control measures and employer responsibilities.

Need to assess dust exposure in your workplace?

Understanding the material, the process and the existing controls is the first step towards an effective approach to industrial dust management. Nederman can help organisations explore suitable extraction and filtration options where these form part of the required control strategy.

To discuss how we can help create a safer, healthier workplace for you and your employees, contact us today.