Respirable Crystalline Silica – get in the know

Exposure to silica is not a new phenomenon - the ancient Greek physician Hippocrates described how miners became breathless as a result of inhaling dust and Bernardo Ramazzini, an eminent Italian physician, described a similar disease in Italian Renaissance artisans.

So what is it?

Silica is a natural substance found in most rocks and is the most abundant compound in the earth’s crust. It’s also present in sand, clay and products such as bricks and concrete. In the workplace these materials create dust when they are cut, drilled or sanded down etc. Some of this dust may be fine enough to reach deep inside the lung and may contain respirable crystalline silica (RCS) that can cause harm to health. Significant exposure can cause silicosis and lung cancer.

“An estimate from the Cancer Burden Study of 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 alone (UK figures).” HSE

Exposure to RCS over a long period can cause fibrosis (hardening or scarring) of the lung tissue with a consequent loss of lung function. Sufferers are likely to have severe shortness of breath and may find it difficult or impossible to walk upstairs or even short distances. The effect continues to develop after exposure has stopped and is irreversible.

How can exposure occur?

Research from Imperial College London suggests that around 900 new cases of lung cancer each year in Britain can be attributed to past exposure to silica dust in construction, granite and stone industries, and various industrial processes. High risk industries include; stone working, brick manufacturing, metal casting and foundries, cement production, mining, quarrying and demolition

Common scenarios where people may be exposed include:

  • Breaking, crushing, grinding or milling silica-containing material such as concrete
  • Moving earth, e.g. excavating, mining, quarrying or tunnelling
  • Drilling, cutting, blasting, chiselling or sanding silica-containing material
  • Using silica, sand or silica-containing products in the manufacturing process of glass and other non-metallic mineral products

How can workplaces minimise or prevent exposure?

On a group level - in a factory or workshop environment, the best strategy is to use engineering controls like enclosures or extraction hoods, and local exhaust ventilation to extract the contaminated air at the point it’s produced. Using water suppression on fixed machinery, and by improvement of housekeeping standards by using vacuums fitted with HEPA filters or wet cleaning methods are also effective methods of control.

On an individual level - where work with hand-held power tools generates dust, the best strategies are to use localised ventilation on the tool or suppress the dust using water spray systems.

As a last resort - in all situations, if it’s not possible to adequately control airborne silica dust using engineering solutions, and air sampling data shows that there is still an unacceptable level of dust, then operatives should use personal respiratory protection equipment (RPE).

How do we monitor it?

The current Workplace Exposure Limit (WEL) in the UK is 0.1 mg/m3. If you are unsure whether your employee exposure exceeds the levels laid down in the COSHH regulations then it would be appropriate to undertake exposure monitoring.

RPS is uniquely positioned to provide a fully integrated respirable crystalline silica service, which will help clients to recognise, evaluate and control occupational exposure to RCS. This service can be tailored in response to the challenges of each client to assist in meeting the requirements of the COSHH regulations. Compliance with prescribed occupational exposure limits, control of the workplace environment and working methods, and staff education will help companies achieve the required level of workers’ protection.

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