Matthew Hayes, director at Synergy Environmental Solutions, details the responsibilities of employers and self-employed construction workers towards respirable crystalline silica (RCS). This CPD aims to provide a technical overview of the risks and responsibilities for assessing and controlling RCS exposure in the workplace.
The Health and Safety Executive (HSE), has refreshed its G404 guidance on health surveillance for those exposed to respirable crystalline silica (RCS).
RCS falls under the Control of Substances Hazardous to Health (COSHH) 2002 Regulations, where dutyholders are legally responsible to protect people from dangerous levels of exposure.
The refreshed publication emphasises the following key points:
Regular exposure to RCS dust: Health surveillance must be a priority when workers are regularly exposed to silica dust.
High-risk occupations: The guidance specifically identifies worktop manufacturing and installation as high-risk jobs where health surveillance must be considered.
Risk-based health checks: It clarifies that health surveillance is a scheme of repeated health checks driven by risk. It’s a COSHH requirement for anyone exposed to hazardous substances. The aim is to spot early signs of ill health and to determine if the risk assessment and control measures need reviewing and updating.
Consulting professionals: The guidance stresses the importance of consulting occupational health professionals.
The HSE recently published its priorities for 2025/26. RCS dust is a priority and is part of the HSE’s drive to reduce occupational lung disease, which results in 12,000 deaths a year. HSE inspectors will be visiting construction companies during this period, so it is important for businesses to not only protect workers but also remain compliant to avoid falling foul of regulations.
What are the risks of RCS?
Crystalline silica is a naturally occurring mineral found in most rocks, sand, and clay. Silica is also present in products such as concrete and bricks, and can be used as a filler in some plastics.
Workplace practices such as cutting, crushing and sanding create dust. Some of this dust is fine enough to breathe deeply into your lungs. These tiny, inhalable particles are known as respirable crystalline silica, RCS or silica dust.
Materials contain different amounts of silica. For example, sandstone contains more than 70% silica, whereas granite contains around 15-30%. The materials used have a big impact on the risks workers face.
Inhaling RCS can lead to several serious lung conditions:
Silicosis: This lung disease occurs from breathing in RCS, causing the lung tissue to harden or scar (fibrosis) and leading to a loss of lung function.
Chronic obstructive pulmonary disease (COPD): This is a group of lung diseases, including bronchitis and emphysema, which cause severe breathlessness, persistent coughing and long-term disability. It is a major cause of death.
Lung cancer: Prolonged and heavy exposure to RCS can cause lung cancer. The risk of lung cancer is even higher if someone already has silicosis.
The good news is that the health risks from RCS are largely preventable. By properly controlling exposure to dust, illness from work activities can be avoided.
Exposure limits
Before detailing RCS exposure limits, we are keen to stress that these limits are the legal limit and results that fall below them do not guarantee the safety of your employees. We recommend that companies aim to achieve <10% of the workplace exposure limit (WEL) in line with the recommendations of BS EN 689:2018.
A list of WELs for COSHH substances can be found in the HSE document EH40/2005 (see Useful Resources below).
WELs are concentrations of hazardous substances. They are averaged over a specified period, referred to as a time-weighted average. Many WELs have two periods, short-term (15 minutes) and long-term (eight hours).
The exposure limits for RCS dust are measured in milligrams per cubic metre. The long-term exposure limit is 0.1mg/m3. The short-term exposure limit – there is no safe exposure.
Because respirable silica is carcinogenic, employers must control it so that it is “as low as reasonably practicable”. Even if exposure is below the exposure limit, companies must use further controls, if available, because there is no safe exposure level to carcinogens.
Common mistakes to avoid
Generic assessments: COSHH assessments must be specific to the workplace and processes, not copied from templates.
Overreliance on PPE: PPE should be a last resort after you have considered all other controls.
Ignoring generated substances: Many risks stem from substances created
during work processes, not just those in containers.
Inadequate communication: Employees must understand the risks and controls, not just have them documented.
Lack of follow-up: Control measures must be implemented and monitored for effectiveness.
COSHH risk assessment
A COSHH risk assessment is a legal requirement in the UK and is a key part of managing workplace health and safety. It is a framework to help you understand risks and establish controls to mitigate them.
An assessment aims to answer these key questions:
- What hazardous substances are present?
- Who is exposed, and how?
- What health risks does the work involve?
- Are existing controls adequate?
- What further steps do I need to take to reduce the risk?
A COSHH risk assessment involves five steps, which can be briefly summarised as follows.
1. Identify hazardous substances: This involves creating an inventory of all substances used or generated in work processes and then reviewing:
- Safety data sheets (SDS).
- Product labels.
- Process flow diagrams.
- Reports of previous incidents or illnesses.
2. Assess the risks: Evaluate how substances cause harm by considering:
- What are the routes of exposure? (inhalation, skin contact, ingestion)
- Who might be exposed? (operators, maintenance staff, cleaners, visitors)
- How often and for how long does exposure occur?
- Are there vulnerable groups? (pregnant workers, young people, asthmatics).
Use workplace exposure limits from the HSE as reference points and consider the cumulative and combined effects of multiple substances.
3. Decide on control measures: Identify existing control measures, such as local exhaust ventilation (LEV), personal protective equipment (PPE) or closed systems, and assess their adequacy. If controls are insufficient, ask yourself:
- Substitution: Can we use a less hazardous substance?
- Process change: Can we modify a substance to reduce exposure?
- Engineering controls: Can containment or ventilation improve?
- Administrative controls: Can we limit access, improve training or implement staff rotation?
- Use personal protective equipment (PPE) only as a last resort.
4. Record the findings: Employers with five or more employees must document assessments. Even in smaller businesses, recording findings is best practice. Your assessment should include:
- Identified hazardous substances.
- The nature and level of risk.
- Existing control measures.
- Additional measures required.
- Responsible persons for implementation.
- The date of the next review.
5. Review and update regularly: Risk assessments should be updated when work processes change, new substances are introduced or after incidents.
Workplace air monitoring is appropriate when you need to determine the effectiveness of control measures or when you need to show WEL compliance. Due to the complexities of air monitoring, we advise appointing an occupational hygienist to carry out the task.
Control measures for RCS
Because silica dust is a carcinogen, there are no safe limits. This requires adopting the ALARP principle, meaning you need to keep exposure levels as low as reasonably practicable.
A key tool for controlling RCS is the hierarchy of control. The hierarchy of control prioritises control measures from most effective to least:
Elimination: The most effective step is to remove the hazardous substance entirely from the workplace.
Substitution: If elimination isn’t possible, replace the hazardous substance with a safer alternative.
Engineering controls: When elimination or substitution isn’t feasible, implement physical controls like local exhaust ventilation (LEV) to reduce exposure at the source.
Administrative controls: If engineering controls are not enough, introduce procedural methods such as safe work practices, job rotation, or restricted access to limit exposure.
Personal protective equipment (PPE): As a last resort, if all other methods are insufficient, provide PPE, such as respirators, to protect individual workers.
Avoid dry sweeping and using compressed air for cleanup, as these create dust clouds. Instead, use vacuum equipment meeting at least dust class M or a suction hose connected to the local exhaust ventilation (LEV) system.
Health surveillance
Where workers are regularly exposed to RCS and have a reasonable chance of developing silicosis, health surveillance is required. Additionally, health surveillance might be appropriate in situations such as:
- If there have been previous cases of work-related ill health on site.
- Respiratory protective equipment (RPE) is heavily relied upon to control RCS exposure.
- If there’s evidence of work-related ill health within the industry.
A robust health surveillance scheme for RCS exposure requires the involvement of a competent occupational health professional.
Key elements include:
Baseline assessment: Assess workers’ respiratory health before exposure to establish a baseline.
Ongoing assessments: Conduct regular assessments at frequencies advised by your occupational health professional.
Comprehensive checks: Health surveillance should include questionnaires, lung function tests and chest X-rays.
Interpretation and action: Occupational health professionals should interpret results for individuals and groups to identify the need for revised risk assessments.
Symptom reporting: Allow workers to report symptoms to a responsible person or occupational health professional.
Record keeping: Maintain a health record for each worker under surveillance, encouraging them to keep a copy for their records.
Investigate concerns: Ensure you investigate employee concerns and consider sick leave data to highlight potential silica-related disease or issues with working practices.
Summary
The key takeaways of this article are:
- Conduct regular COSHH Risk Assessments: follow the five steps outlined above.
- Call upon occupational hygiene and health professionals to utilise their expertise.
- Provide regular health surveillance for workers exposed to silica dust.
- Maintain regular communication and training with employees so they know how to work safely, where to report issues, and understand safety best practices. n
Matthew Hayes is director at Synergy Environmental Solutions. He is a BOHS-accredited occupational hygiene consultant with extensive experience in COSHH compliance, workplace air monitoring and safety related to noise and vibration.
Useful resources
HSE G404: www.hse.gov.uk/pubns/guidance/g404.pdf
HSE list of WELs for COSHH substances: www.hse.gov.uk/pubns/priced/eh40.pdf
HSE health surveillance guidance: www.hse.gov.uk/pubns/books/healthsurveillance.htm
