Understanding Silica and Hazardous Workplace Dust

Silica and other hazardous dusts are produced by many routine activities, particularly in construction, demolition, refurbishment and manufacturing.

Dust-producing activities include:

• Cutting concrete, bricks, blocks, tiles and stone.
• Drilling, grinding, sanding and chasing.
• Breaking out concrete or demolishing walls.
• Mixing cement, mortar and other powdered materials.
• Dry sweeping contaminated work areas.
• Cleaning tools or surfaces with compressed air.

The smallest particles can remain airborne and penetrate deep into the lungs. Respirable crystalline silica may be impossible to see, so the absence of a visible dust cloud does not mean that the air is safe.

Health Effects of Silica Dust Exposure

Breathing respirable crystalline silica can cause serious and irreversible damage. The effects may develop gradually, and a worker may not notice symptoms during the early stages of disease.

Silica dust exposure is associated with conditions including:

• Silicosis, an incurable disease involving permanent scarring of the lungs.
• Lung cancer.
• Chronic obstructive pulmonary disease (COPD).
• Long-term breathing difficulties and reduced lung function.
• An increased risk of conditions including tuberculosis and kidney disease.

Symptoms may include coughing, breathlessness, wheezing, chest tightness and extreme tiredness. By the time significant symptoms develop, the lung damage may already be permanent.

Legal Duties for Controlling Silica Dust

Under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), employers must assess the risks from hazardous dust and prevent exposure where reasonably practicable.

Where exposure cannot be prevented, it must be adequately controlled. Because work that generates respirable crystalline silica is subject to stringent COSHH requirements, exposure should be reduced to as low a level as is reasonably practicable.

Employers must:

• Complete suitable and sufficient COSHH risk assessments.
• Select effective control measures.
• Provide suitable equipment and ensure that it is properly used.
• Inspect, maintain, examine and test controls as required.
• Provide information, instruction, training and supervision.
• Review assessments and controls when circumstances change.
• Provide health surveillance where the relevant COSHH conditions are met.

Controlling silica dust is a legal duty, not an optional workplace precaution.

Using the Hierarchy of Control

Silica dust risks should be managed using the hierarchy of control. Employers should begin with measures that eliminate the hazard or prevent dust from being produced.

1. Eliminate the dusty task where reasonably practicable.
2. Substitute the material, tool or process for a safer alternative.
3. Apply engineering controls to capture or suppress dust at its source.
4. Use administrative controls to organise and supervise the work safely.
5. Provide suitable RPE as additional protection where residual exposure remains.

RPE should not be used as a substitute for reasonably practicable engineering controls.

Engineering Controls for Silica Dust

Engineering controls provide strong protection because they prevent dust from becoming airborne or capture it close to where it is created.

Suitable engineering controls may include:

• On-tool extraction connected to an appropriate industrial dust extractor.
• Water suppression and wet cutting.
• Local exhaust ventilation.
• Extraction booths and enclosed processes.
• Isolation of automated or high-dust activities.

For construction dust, an M-class extractor will normally be the minimum suitable dust classification. An H-class extractor may be required where identified by the risk assessment.

Domestic vacuum cleaners are not suitable for collecting hazardous construction dust.

Administrative Controls and Safe Working Practices

Administrative controls support engineering measures by improving the way dusty work is planned, organised and supervised.

Important administrative controls include:

• Planning and assessing work before it begins.
• Scheduling dusty tasks when fewer people are present.
• Sequencing work to protect other trades and site users.
• Establishing exclusion zones around dusty activities.
• Restricting access to trained and authorised workers.
• Providing suitable information, instruction and training.
• Monitoring the work and enforcing the required controls.

Limiting the duration of exposure may provide additional protection, but rotating workers must not replace effective source controls or unnecessarily increase the number of people exposed.

Housekeeping and Safe Dust Removal

Good housekeeping prevents settled dust from being disturbed and released back into the air. Work areas should be cleaned regularly using suitable methods.

Safe cleaning methods include:

• Using an appropriate M-class or H-class dust extractor.
• Using suitable wet-cleaning methods.
• Damping down dust before carefully collecting it.
• Placing waste directly into suitable sealed bags or containers.
• Emptying extraction equipment using the manufacturer's safe procedure.

Dry sweeping and cleaning with compressed air should be avoided because they release settled dust back into the workplace air.

Respiratory Protective Equipment

Where other measures cannot adequately control residual exposure, employers must provide suitable respiratory protective equipment (RPE) as additional protection.

RPE must be:

• Adequate for the hazardous substance and expected exposure.
• Suitable for the task, environment and individual wearer.
• Compatible with other personal protective equipment.
• Properly maintained, cleaned and stored.
• Worn correctly whenever required.

Anyone using tight-fitting RPE must pass a face-fit test for the particular make, model, type and size of respirator provided. Workers must also be clean-shaven wherever the mask needs to seal against the face.

Responsibilities of Managers and Supervisors

Managers and supervisors are responsible for turning written procedures into effective workplace controls. They must ensure that assessments are implemented and safe systems of work are consistently followed.

They should confirm that:

• The required controls are available before work begins.
• Extraction and suppression equipment is used correctly.
• Equipment is regularly inspected and properly maintained.
• Workers wear suitable RPE when required.
• Exclusion zones and housekeeping arrangements remain effective.
• Unsafe practices are stopped immediately.
• Workers understand how to report defects and health concerns.

Regular monitoring, clear communication and consistent enforcement are essential. If a critical control fails, the affected work should stop until adequate protection has been restored.

Health Surveillance and Reporting Symptoms

Health surveillance must be provided where the COSHH risk assessment and relevant legal conditions show that it is required. It can help identify early signs of work-related respiratory ill health and indicate whether controls may be failing.

Workers should attend surveillance appointments and promptly report symptoms such as persistent coughing, breathlessness, wheezing or chest tightness.

Employers must act on relevant health-surveillance findings and competent occupational health advice. This may require reviewing exposure, improving controls or preventing further exposure.

Health surveillance supports effective dust control but does not replace it.

Final Silica Dust Safety Message

Silica dust is a serious workplace hazard, but exposure can be prevented or adequately controlled through suitable planning, effective engineering measures, safe working practices and strong management oversight.

Before dusty work begins, remember to:

• Assess the materials, tasks and potential exposure.
• Prevent dust generation wherever reasonably practicable.
• Control remaining exposure at its source.
• Protect workers with suitable RPE where additional protection is required.
• Check that controls remain effective throughout the task.
• Review the arrangements when work changes or problems are identified.

Protecting workers from silica and hazardous dust is both a legal responsibility and a fundamental part of maintaining a safe, healthy and professional workplace.