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Respirable Crystalline Silica (RCS) In-Depth Guide

Overview

  • Respirable Crystalline Silica (RCS) is the second biggest risk to construction workers after asbestos and is linked to severe respiratory failure, including lung damage and chronic silicosis.

  • This guide explores what RCS is, who is at risk, and how UK COSHH regulations require employers to protect workers from exposure.

  • Learn about legal responsibilities, Personal Protective Equipment (PPE)guidance, workplace limits, and the steps needed to reduce the risk of long-term health issues from silica dust.

Silica is the biggest risk to construction workers after asbestos. Heavy and prolonged exposure to RCS can cause lung cancer and other serious respiratory diseases. The Health and Safety Executive (HSE) estimates that silica dust exposure contributes to over 500 construction worker deaths annually in the UK. Keep reading for an in-depth look at essential information on silica dust control and safety.

For a full breakdown of workplace dust risks, see our main Dust at Work page.

What is Respirable Crystalline Silica (RCS)?

Crystalline silica is what makes up rocks, granite, and even sand. Products such as concrete blocks, bricks and mortar are primarily made of crystalline silica. In this form, the crystalline silica is harmless; however, when the concrete block is drilled, sanded, cut, or chipped, it creates a cloud of fine dust, which is classified as respirable crystalline silica (RCS). If inhaled, it can prove extremely deadly.

To learn more about the different types of dust, check out our article: Types of Dust in the Workplace.

workman creating dust

Some industries are more at risk than others. Industries that are exposed to RCS more often include:

  1. Mining – where the Earth’s crust is involved.

  2. Construction Work

  3. Sandblasting

  4. Glass manufacturing

  5. Steel Industry

  6. Stone Cutting

  7. Quarrying

  8. Abrasive Blasting

  9. Cement and Brick Manufacturing

  10. China and Ceramic Manufacturing

How Harmful is RCS if Inhaled?

Inhaling respirable crystalline silica dust can lead to the following conditions:

  1. Silicosis

  2. Lung disease

  3. Chronic obstructive pulmonary disease (COPD)

  4. Kidney disease

Intense short-term exposure or prolonged long-term silica exposure can lead to many health issues. Taking simple steps can ensure safety. For an overview of the health risks of dust, including RCS, read our Can You Get Sick from Dust Inhalation? article.

Who is at risk from RCS exposure?

Without adequate training on safety measures related to RCS, construction workers are one of the groups most at risk. RCS, however, affects more than just construction workers; it has been noted to be a danger to people working in quarries and mines.

For practical steps to reduce exposure, visit our guide on effective dust control measures.

How much exposure to silica dust is dangerous?

Even a small amount of RCS can create a health hazard. In the UK, the workplace exposure limit (WEL) for RCS is 0.1 mg/m³ averaged over eight hours.

This limit is defined under the Control of Substances Hazardous to Health Regulations 2002 (COSHH). It's crucial to understand that this is the maximum allowable concentration, and employers should strive to keep exposure levels well below this limit to ensure worker safety.

Silica dust next to a penny for size reference

How much RCS dust can harm you, shown next to a penny for scale.

Calculating Time Weighted Average:

As per the HSE, ”The term ‘8-hour reference period’ relates to the procedure whereby the occupational exposures in any 24 hours are treated as equivalent to a single uniform exposure for 8 hours (the 8-hour time-weighted average (TWA) exposure).” EH40/2005 Workplace exposure limits Page 34.

The following formula is used to calculate the time-weighted average:

= duration x average concentration ÷ 8

Example: Where a site worker on an 8-hour shift is exposed to a substance during that period at a level of 25mg/m3, the time-weighted average would be calculated as:

(8x25)/8 = 25mg/m3

Is RCS considered a carcinogen?

The International Agency for Research classifies RCS as a Category 1 Carcinogen. A carcinogen is any substance that causes cancer in humans. A Category 1 carcinogen is known to cause cancer in humans.

I wear a mask. Am I safe from RCS?

No, respirable crystalline silica is too fine to be stopped by a normal mask alone. Even with water suppression, the HSE recommends using a face mask with a protection factor of 20. For further guidance on AFP 20, please check the HSE COSHH Essential: Respiratory protective equipment (RPE) - R3 document. An assigned protection factor of 20 or APF 20 means that you only breathe in 1/20 of the dust in the air. Construction dust CIS36

What not to do when cleaning up RCS

  1. Dry sweep – use vacuum or wet cleaning

  2. Use compressed air to remove dust from clothing.

Is Silicosis treatable?

There is no known cure for silicosis. Prevention is the only way to protect yourself from the disease. Once silicosis has developed, the doctors will “manage” the disease.

The Symptoms of Silicosis

The main symptoms of silicosis:

  • Persistent cough

  • Shortness of breath, especially during physical activity

  • Chest pain or discomfort

  • Fatigue and weakness

  • Weight loss in advanced cases

  • Increased susceptibility to lung infections

Early identification of these symptoms is important for maintaining health and safety standards.

When to See Your Doctor

Regular health check-ups are recommended if you work in an industry that has exposure to RCS. Generally, if you have a breathing difficulty that does not improve over a period of time, then you should get checked by a doctor.

Employers are required by law to:

The employer is obliged by law to carry out a risk assessment for the work activities. The risk assessment is carried out to identify the controls and measures by which exposure could lead to higher levels than dictated as safe. Employers must abide by the Control of Substances Hazardous to Health Regulations 2002 (COSHH) and need to:

  1. Keep written records of any risk assessment. This applies to employers that have more than five workers.

  2. Disclose any pertinent details found in the risk assessment.

  3. Try to prevent and control exposures to RCS.

  4. Provide proper PPE where necessary.

  5. Provide adequate instruction and training on the safe use of equipment.

  6. Ensure that the WEL for RCS is not exceeded through monitoring and implementing controls.

Commodious offers an advanced level 2 online Advanced COSHH Training Course specifically designed for employers, managers and supervisors with responsibility for the welfare of employees and the management and control of substances hazardous to health. Commodious also now provides a specific 'Dust Awareness Training Course'.

Employee Responsibilities

Employees, whether full-time or part-time, have a legal duty to ensure their health and safety while at work.

You should always:

  1. Ensure your safety and the safety of those around you.

  2. Ask how to execute the job that you are assigned safely.

  3. Ask if the work you are doing involves the risk of being exposed to RCS.

Conclusion

RCS is a major health threat, but with correct training, monitoring, and COSHH-compliant control measures, it can be effectively managed. Protecting workers from silica dust is essential for preventing permanent respiratory damage and maintaining a safe workplace.

For more support, you can read our Dust at Work Topic, check our Dust at Work FAQ, or explore our dust control measures guide for practical steps on reducing exposure.

Bethany Wesson

Bethany Wesson

Bethany is a freelance content writer and has produced articles for the Commodious Knowledge Bank since 2023. She has written about various health and safety topics, from asbestos to wellness in the workplace.

  • Dust
  • Hazards
  • COSHH