Share this article:
Michael O Connor, QEHS Manager with Mercury Engineering, outlines how to reduce the risks of Respirable Crystalline Silica (RCS)
Historically, dust within the construction industry has been an acceptable aspect of particular tasks.
This perception has changed hugely over the last 20 years with more and more controls being introduced at the design and construction phases of projects.
Mixing, cutting, drilling, demolition of silica containing materials has created the largest volumes of project dust. Concrete, stone, sandstone, sand based materials are silica based materials.
The respirable fraction of the dust is invisibly fine. The OELV for Respirable Crystalline Silica (RCS) is 0.1mg/m3 averaged over 8 hours, as set down in the HSA Chemical Agents Code of Practice under the Safety, Health and Welfare at Work (Chemical Agents) Regulations 2001.
Inhalation is the primary exposure route for RCS. Silica can be present as a hazard from the quarry through the construction phase and onto the demolition/alteration of completed structures.
By breathing in RCS, you could develop the following lung diseases:
Silicosis: Silicosis makes breathing more difficult and increases the risk of lung infections. Silicosis usually follows exposure to RCS over many years, but extremely high exposures can lead rapidly to ill health.
Chronic obstructive pulmonary disease (COPD): COPD is a group of lung diseases, including bronchitis and emphysema, resulting in severe breathlessness, prolonged coughing and chronic disability. It may be caused by breathing in any fine dusts, including RCS. It can be very disabling and is a leading cause of death. Cigarette smoking can make it worse.
Lung cancer: Heavy and prolonged exposure to RCS can cause lung cancer. When someone already has silicosis, there is an increased risk of lung cancer.
However, the health risks from RCS are insignificant when exposure to dust is adequately controlled. You do not need to become ill through work activities.
What kind of tasks on RCS containing materials create hazards?
- Grinding, drilling, cutting, sanding, blasting
- Mixing and handling, brushing and shovelling of dry materials
- Rock breaking, drilling, crushing, screening
How can we eliminate/mitigate these hazards?
- Commence with a risk assessment (knowledge of the % silica in a material is a distinct advantage.) The risk assessment shall take account of the personnel/company completing the works, plus other personnel who could be affected by the hazards created.
- Eliminate hazards where possible through early accurate design e.g. the formation of opes at concrete pouring stage.
- Use of remotely operated machinery in an open, well ventilated environment.
- Substitution of non-silica or lower level silica containing products at design stage.
- Offsite fabrication in controlled environments.
- Make all employees aware of the hazards in advance.
- Plan via a RAMS, which shall include task methodology, controls in place, training required, disposal of RCS containing dust, air monitoring as required (before and after depending on the ventilation/air exchange rate of the location.)
- Reduce exposure times for personnel.
- Forced extraction/ventilation for enclosed spaces.
- Air monitoring.
- Personal monitoring.
- Wet down all RCS containing materials during the cutting process – road saws, consaws, hole saws are good examples, where water can be used to eliminate RCS hazards at the cutting stage (it is important that the wet dust is disposed of safely before it turns to dust and the wetting down procedure was wasted as the hazard remains on the project.)
- Create a culture of completing all cutting externally to the project – in roofed open-ended cut shops.
- Never sweep up RCS containing dust – use an approved vacuum.
PPE has a hugely important role in reducing exposure to RCS. Depending on the risk assessment, respirators may be required to increase your personal safety. All personnel who wear respirators must be trained by a competent person and know how to use, check and clean, or know when to replace the respirator/filters.
Disposable respirators/face masks also require training to allow for safe use and remember, that a person should be clean shaven to allow this type of respirator work effectively.
Make this Construction Safety Week, a time to increase RCS awareness within your company and always risk assess your tasks, eliminate or mitigate RCS hazards, train your personnel, monitor you workforces’ health, plan for a safe workplace, stick to the plan and let’s get everyone home safely to their families every day.