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
Is RCS classified as a carcinogen?
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'.
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:
Inhaling respirable crystalline silica can lead to the following conditions:
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.
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.
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])
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).
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
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.
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
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.
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.
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.
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'.
Employees, whether full-time or part-time, have a legal duty to ensure their health and safety while at work.
You should always: