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respirable Crystalline silica
The inhalation of fine crystalline silica dust is associated with silicosis and other lung illness. Particles are most often generated in workplaces where materials are cut, sanded or drilled, creating fine dust. The following information should be considered when determining how to manage respirable crystalline silica (RCS) exposures in the workplace.
Harmful effects of silica
Silica or silicon dioxide (SiO2) is a very common mineral. It occurs in many products including sandstone, concrete, brick and engineered/ manufactured stone. Silica is also known as quartz, tripoli and cristobalite. Crystalline silica is harmful when respirable-sized dust of less than 10 microns is breathed deep into the lungs, as this can cause lung scarring known as silicosis.
The fibrosis of the lungs and the associated inflammation may lead to lung cancer. There is evidence that fresh cut silica particles, with active surfaces, may be more harmful than aged surface modified (less active) particles
Exposure levels
Studies show that people who have RCS exposure greater than 0.065mg/m3 over their working life have an increased risk of lung cancer. At a lifetime average exposure of 0.06mg/m3, the risk of silicosis is estimated at 7%. The current Australian workplace exposure standard (WES) is 0.1 mg/m3 for an 8-hour working day over a 40-year working life. However medical health monitoring is suggested for ongoing exposures of 0.05mg/m3 RCS over 8 hours
Types of work with potentially harmful exposures
The potential for high RCS exposures exists in the following industry sectors.
Manufacturing
Manufacturing stone items can cause a dust exposure risk. However the use of engineered or composite stone materials, such as Caesarstone and Silestone, for benchtops in both domestic and commercial premises has increased markedly in the last 10-15 years.
This change in product usage is likely to have increased quartz dust exposure for workers fabricating benchtops by cutting, drilling or polishing. Whereas natural stone products like granite may contain up to 40% crystalline silica (quartz) by weight, the engineered products may have 93% or higher quartz content.
Mining, quarrying, tunnelling and extractive minerals
Exposure to RCS is a known issue, with risks especially during rock crushing activities. Silicosis prevention in South Australia is assisted by the Mining and Quarrying OHS Committee.
Construction, building and demolition
Fine silica dust can be formed on sites from concrete cutting and using dust generating tools on stone.
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PCBU responsibilities
As a Person Conducting a Business or Undertaking (PCBU) you must determine if an RCS dust exposure risk exists at your workplace. This can be done by measuring the workplace or reviewing data, such as for tool extraction systems etc.
Control for RCS dust exposure must be put in place if the exposure can’t be eliminated. The work health and safety (WHS) hierarchy of risk control, ranked from the highest level of protection and reliability to the lowest, suggests the following controls:
Engineering controls – dust suppression
• apply water suppression systems to reduce dust generation.
Engineering controls – dust extraction /LEV
• use local exhaust ventilation (LEV) systems to remove dust at the source
• ensure LEV is correctly placed and operates at effective flow rates • use dust removal systems on tools to reduce dust exposure of mobile
workers.
Engineering controls – isolation / containment
• isolate areas of the workplace where dust is generated by other workers
• exhaust and filter air from the isolated area.
Administrative controls
• ensure regular housekeeping to prevent the accumulation of dust • restrict time of exposure / use worker rotation.
Personal protective equipment
• provide personal protective equipment (PPE) that is suitable for the nature of the work and the hazard, is comfortable to wear and of a suitable size and fit, is maintained / repaired / replaced when needed, and is used or worn by workers trained in its use and care
• assess levels of personal exposure among workers performing high risk tasks.
You must provide suitable information, training, instruction and supervision to workers in the use, storage and handling of hazardous chemicals, taking into account the nature of the work, the associated risks and any control measures implemented. You must also review and revise your control measures, as necessary, to maintain a safe work environment that is without risk to health or safety, so far as is reasonably practicable. This may include both worksite, via an occupational hygienist, and external health monitoring.
If health monitoring is undertaken, records must be kept for 30 years. Health monitoring must be undertaken by a registered medical practitioner, such as thoracic society registered, familiar with the national requirements for silica health monitoring.
For more information on this topic contact SafeWork SA – 1300 365 255 Source: SafeWork SA