Respirable Crystalline Silica (RCS) In-Depth Guide

Worker Producing RCS Dust
Working with Residual Crystalline Silica Dust - RCS

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. HSE commissioned estimates it was responsible for the death of over 500 construction workers in 2005. In addition to the risks from lung cancer, silica is also linked to other serious lung diseases:

Silicosis can cause severe breathing problems and increases the risk of lung infections. Silicosis usually follows exposure to RCS over many years, but extremely high exposures can cause acute silicosis more quickly.
Chronic obstructive pulmonary disease is a group of lung diseases including bronchitis and emphysema. It results in severe breathlessness, prolonged coughing and chronic disability. It can be very disabling and is a leading cause of death. Around 4000 deaths are estimated annually due to COPD resulting from past workplace exposures in the past. Construction workers are a significant at risk group within this. (UK Health & Safety Executive).

The following article takes a deep dive into RCS, answering pertinent questions such as

What is RCS dust?
Who is at risk from respirable crystalline silica?
What are the hazards associated with exposure to RCS?
Is wearing a mask enough to protect you from RCS?
Is RCS classified as a carcinogen?
What are your responsibilities as mandated by UK law for controlling RCS dust exposure on your site or working area?

Commodious offers a COSHH Awareness Course Online. The level 1 course is designed to provide awareness of the dangers associated with hazardous substances and the management and control measures required to control the risks. Commodious also now provides a specific 'Dust Awareness Training Course'.

What is Respirable Crystalline Silica?

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 same 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.

The following is a high-level list of industries that are exposed to RCS:

Mining - where the Earth’s crust is involved.
Construction Work
Sand Blasting
Glass manufacturing
Steel Industry
Stone Cutting
Quarrying
Abrasive Blasting
Cement and Brick Manufacturing
Chine and Ceramic Manufacturing

How Harmful is RCS if Inhaled?

Inhaling respirable crystalline silica can lead to the following conditions:

Silicosis
Lung cancer
Chronic obstructive pulmonary disease (COPD)
Kidney disease

Intense short term exposure or prolonged long term exposure to RCS can lead to a multitude of health issues. Taking simple steps can ensure safety.

Who is at Risk from RCS exposure?

According to a study conducted by the Health and Safety Executive, "the number of deaths from lung cancer associated with exposure to RCS shows there are around 600 deaths per year with 450 of these occurring from exposures in the construction sector."

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.

How much Respirable Crystalline Silica Dust does it take to cause damage?

A small amount of RCS can create a health hazard. In 2006 the HSE set the Workplace Exposure Limit (WEL) for RCS of 0.1 mg/m3 expressed as an 8-hour time-weighted average (TWA). The WEL as per the HSE is "A Workplace Exposure Limit is the maximum concentration of an airborne substance, averaged over a reference period, to which employees may be exposed by inhalation. This means it is a figure that, at worst, should not be exceeded." (Respirable Crystalline Silica [RCS])

Silica Dust Scale
The amount of RCS dust that is harmful, if inhaled - compared to a penny coin.

Image: Construction dust CIS36

In Britain, RCS exposure has a workplace exposure limit (WEL), which contains exposure below a set limit, preventing excessive exposure. The WEL for RCS is 0.1 mg/m3 expressed as an 8-hour time-weighted average (TWA). Exposure to RCS is also subject to the Control of Substances Hazardous to Health Regulations 2002 (COSHH).

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-hour period 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 and 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: Repiratory 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

Dry sweep – use vacuum or wet cleaning
Use compressed air for removing 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.

When to See Your Doctor

Regular health checkups 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 time then you should get checked by a doctor.

Responsibilities and the Law regarding Respirable Crystalline Silica, RCS

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:

Keep written records of any risk assessment. This applies to employers that have more than five workers.
Disclose any pertinent details found in the risk assessment.
Try to prevent and control exposures to RCS.
Provide proper PPE where necessary.
Provide adequate instruction and training on the safe use of equipment.
Ensure that the WEL for RCS is not exceeded through monitoring and implementing controls.

Commodious offer an advance 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:

Ensure your safety and the safety of those around you.
Ask how to execute the job that you are assigned safely.
Ask if the work you are doing involves the risk of being exposed to RCS.

Silica RCS