Crystalline silica - technical fact sheet
Why is crystalline silica a priority chemical?
The NSW Work health and safety roadmap has a target of a 30% reduction in serious injuries and illnesses by 2022, which comprises a reduction in exposures to hazardous chemicals and materials. An initial list of 100 priority chemicals was developed based on national and international sources. This list was further refined using the following criteria: toxicity rating, exposure potential, estimated quantities used and potential number of workers using these chemicals. Crystalline silica ranked the second highest based on these criteria. Crystalline silica is a very common mineral used in manufacturing building products and in construction materials. Applying adequate controls such as minimising the generation of airborne dust can reduce hazardous exposures and prevent illness in the workplace.
Sources of exposure
Materials and products containing crystalline silica include shale, sandstone, concrete, bricks and manufactured stone. Workers can come across crystalline silica during excavation or tunnelling through quartz containing rock such as shale or sandstone. A health hazard is created when the very fine particles of crystalline silica can be inhaled. The size fraction of airborne dust that can reach the lungs where air exchange takes place is known as the 'respirable fraction'. Once particles become larger than about seven microns (1 micron = 1/1000 mm) in diameter, they are no longer respirable.
Significant levels of airborne dust are most likely to occur when materials or products in the workplace are cut, sanded, drilled or during any other activities which create fine dust. Exposures in workplaces can also occur through dry sweeping or using compressed air (rather than wet cleaning or using a vacuum with HEPA filter) and re-suspension of settled dust from clothing or fabric materials.
Respirable crystalline silica (RCS), depending on factors such as how much dust a worker breathes in and for how long, can cause silicosis. Silicosis is a fibrosis (scarring) of the lung resulting in loss of lung function. This fibrosis is incurable and continues to develop after exposure has stopped. Persons with advanced silicosis suffer severe shortness of breath and may suffer complications such as heart failure.
Silicosis can be further classed into:
- chronic (or classic) silicosis, typically observed in workers after 15 years or more since they were first exposed;
- accelerated silicosis, appearing in workers after high exposure over a shorter period of time (five to 10 years); and
- acute silicosis, observed in workers within a few months to two years after exposed to silica at very high concentrations. Acute silicosis can cause very serious health effects and is life threatening.
Significant long term exposure to crystalline silica has also been associated with an increased risk of developing lung cancer.
Labelling and safety data
Manufacturers and importers of products containing crystalline silica (a hazardous chemical) need to determine if workers can be exposed to the respirable fraction of airborne dust when working with these products eg when cutting. Where exposure to RCS can occur, products must be labelled and safety data sheets provided (see clauses 329, 330 and 335 of the Work Health and Safety Regulation 2017 (WHS Regulation).
Suppliers of a hazardous chemical to a workplace must provide current safety data sheets.
A person conducting a business or undertaking (PCBU) must also obtain a copy of the safety data sheet and make it readily accessible to workers involved in using, handling or storing the hazardous chemical at the workplace (cl 344).
Exposure standards and air monitoring – WHS Regulation
Respirable crystalline silica has a workplace exposure standard of 0.1 mg/m3 averaged over eight hours. Risks to health and safety from exposures to hazardous chemicals must, so far as is reasonably practicable, be eliminated. PCBU’s must ensure that no person at the workplace is exposed to a substance above its exposure standard and must reduce exposures so far as is reasonably practicable.
PCBU’s must undertake personal exposure (air) monitoring for substances with an exposure standard if they are not certain (on reasonable grounds) as to whether or not the exposure standard is exceeded.
Adjustments to the exposure standards are made for extended work shifts, taking into account the longer daily exposure. Air monitoring results must be readily available to workers and records of results kept for 30 years (cl 50).
Health monitoring – WHS Regulation
PCBU’s are required to provide health monitoring to workers if there is a significant risk to the worker’s health because of exposure to crystalline silica.
Crystalline silica is listed in Schedule 14 of the WHS Regulation 2017 which outlines the health monitoring requirements.
In relation to health monitoring, PCBU duties include:
- informing workers of the requirements for health monitoring
- using a registered medical practitioner with experience in health monitoring
- providing details to the medical practitioner
- obtaining a copy of the health monitoring report
- providing a copy of the health monitoring report to SafeWork NSW if the worker has developed a disease or injury and/or the report contains any recommendations on remedial measures at the workplace
- keeping records of health monitoring for 30 years.
Workers exposed to respirable crystalline silica at levels or a frequency not resulting in a significant risk to health, are not required to undergo health monitoring.
Workers relying on personal protective equipment (PPE) such as respirators for controlling their exposure below the exposure standard must be included in health monitoring.
Where risks to health and safety cannot be eliminated the hierarchy of controls must be applied in accordance with the WHS Regulation to minimise risk. For instance:
- applying water suppression systems to reduce dust generation
- use local exhaust ventilation systems to remove dust at the source
- ensure such ventilation is correctly placed and operates at effective flow rates
- use dust removal systems on tools to reduce dust exposure of mobile workers
- isolate areas of the workplace where dust is generated by other workers
- assess the level of personal exposure among workers performing high risk tasks
- ensure regular housekeeping in dusty work areas to prevent the accumulation of dust
- provide suitable PPE, including a program to correctly fit, instruct on use and ensure regular maintenance of respiratory protective equipment (RPE).
PCBU’s must provide suitable information, training, instruction and supervision to workers using, storing and handling hazardous chemicals regarding the nature of the work, risks and the control measures implemented.
PCBU's with duties under the WHS Regulation 2017 must review and revise control measures, as necessary, to maintain a work environment so far as reasonably practicable, that is without risk to health or safety.
Where to find more information
Codes of practice
These codes of practice provide more detailed information on how you can achieve the standards required:
- Managing the risks of hazardous chemicals in the workplace
- Preparation of safety data sheets for hazardous chemicals
- Labelling of workplace hazardous chemicals
- Construction Work
Safe Work Australia guidance material
- Workplace exposure standards for airborne contaminants
- Guidance on the interpretation of workplace exposure standards for airborne contaminants
- Health monitoring for exposure to hazardous chemicals – guide for persons conducting a business or undertaking
- Health monitoring for exposure to hazardous chemicals – guide for workers
- Guide for tunnelling work
- AS/NZS 1715-2009 Selection, use and maintenance of respiratory protection
- AS/2985-2009 Workplace atmospheres method for sampling and gravimetric determination of respirable dust
You can download a PDF version of this technical fact sheet.