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  • Gary Clarkson

and another one bites the dust.......

Given some recent observations of the on-going construction work in town as well as the imminent arrival of thousands of construction workers to support the major developments soon to kick off. I thought it timely to raise the issue of exposure to silica dust again.


Respirable Crystalline Silica (RCS), or Silica for short, is present in many products such as:

  • stone products (natural and composite)

  • manufactured stone bench tops

  • bricks

  • cement

  • asphalt

  • concrete

  • drywall and some plasterboards

  • grout

  • mortar

  • tiles

  • some plastic materials

When we mix those powdered products or use abrasive processes on the others we release dust. It's pretty obvious to anyone who has been on-site.


But the issue is, the dust we can see is not the problem.


Respirable silica dust is invisible to the naked eye and can hang in the air for a long time after work has finished for the day. The larger visible dust particles settle long before the invisible silica dust particles do. This means our workforce can breathe in respirable dust even if it cannot be seen in the air.

Silica particles are smaller than 10 microns (μm)

Respirable crystalline silica particles are less than 10 microns (μm) in diameter and when breathed in can go deep into our lungs


Exposure to silica dust, is known to cause serious lung disease such as Silicosis, Chronic Obstructive Pulmonary Disease (COPD) and kidney disease among other things.

It is also a major contributor to the development of lung cancer.

This is not just a 50 something safety guy saying this, it's based on lots of international epidemiological studies. - Google it, but if caring for people is your thing, it does not make for particularly pleasant reading.


There are three types of silicosis - acute, chronic and accelerated. Silicosis is irreversible and often fatal. Symptoms of these diseases may not appear for many years after exposure.


Sadly, someone could be diagnosed with these diseases and not show any symptoms, even after they have been diagnosed. This is why preventing exposure and monitoring the health of those working with these products is critical.


If the folks under your control as employees or contractors are cutting, grinding, sanding, drilling and polishing silica containing products or carrying out any activities that release silica dust into the air, then there is a significant risk that without effective controls they will be exposed to respirable silica dust and develop an illness or disease.

No ifs, no buts, no maybes !


So what can you do to keep your people safe?


Eliminating exposure to silica dust must be the starting point and the solutions are really quite simple.

  • Use wet cutting methods to keep the dust down.

  • Purchase some of the fantastic power tool attachments which capture the dust at source, just make sure you have trained people to use, maintain and clean them.

  • Set-up exclusions zones to protect others from exposure

  • And for goodness sake, vacuum up any residual dust, don't sweep it up.

If you need any hep with putting these things in place or want to purchase some dust extraction tools and attachments, just let me know. There are some great people in town who can supply your needs.


But 50 something safety guy, you haven't mentioned dust masks !


You should never rely solely on PPE to protect workers from silica dust.

Before you put your people in PPE you need to do a risk assessment to see what other controls can and should be used first.

PPE should only be considered after all other controls have been exhausted and should only be used to supplement higher-level control measures or when no other safety measures are available.


Dust masks are a good additional control, but only if you choose the correct one and its fitted properly.

The correct dust mask is dependent on a number of variables such as;

the amount of dust, the work process as well as the individual and their face shape.


If you need help with picking the best solution for your needs, give me a call.


What does not get measured does not get managed


You should also consider some form of personal air monitoring for those working with silica products to determine if the levels in the workplace are over the workplace exposure standards set by Worksafe NZ.


At present this is 0.1mg/m3 of air, measured over an 8 hour time weighted average. It's not a lot of dust.

a typical monitoring set-up

The monitoring is done by measuring dust in the workers breathing zone to determine what they are being exposed to. It won't stop them doing their work, but it will give you some hard data to help decide if you have a problem work process or not.


If you need this type of service, please get in touch with me and I shall put you in contact with the right people.


Health Monitoring


Regular health monitoring for the people working with these products is essential to make sure we are controlling the risk properly. Health monitoring should begin at the time a worker is first employed or when they first start working with silica and silica containing products. This is so that any changes to the worker’s health can be detected early.


Health monitoring for silica dust includes workers being screened with specialised equipment. So a qualified occupational health provider is essential to make sure you catch issues before they become serious.


Some useful resources


I have some really good sources of information to explain this health issue in a bit more detail as well to outline our legal responsibilities, which I would like to share with you.


  • Our awesome people at Worksafe NZ have put together a suite of information here.

  • Safe Work Australia always seem to come up with the goods and since their legislation is so similar to ours, this is useful. Check it out here.

  • I can't help but go back to the good old HSE in the UK. While the legal side is different, the principles are similar. Have a look here.


I hope this gives you some food for thought. By working together we can start to reduce the impact of these substances on our workforce.


If you need any help with managing silica exposure or any other safety and health support, please don't hesitate to get in touch.