The human body has developed a remarkable mechanism for responding to threats, known as the fight-or-flight response, which is intricately linked to our five senses.
When you perceive a danger (real or imagined), a physiological reaction is activated within your autonomic nervous system, particularly the sympathetic component. This response readies your body to either confront the danger head-on or make a speedy escape.
Perception (for the most part) relies on our five senses: touching, tasting, smelling, hearing, and seeing.
First, our eyes, one of our primary senses, play a pivotal role in threat detection. When we see a threat, the visual information is processed by the brain's amygdala, which acts as an emotional alarm system. This rapid processing allows us to assess the situation quickly and initiate a response. Run! There's a koala coming straight at cha!
Similarly, our sense of hearing plays a crucial role in the fight-or-flight response. Sudden loud noises or ominous sounds can trigger a release of stress hormones, preparing the body for action.
Our sense of touch can also contribute; a sudden, unexpected touch or a feeling of pain can prompt immediate reactions. How fast do you pull your hand away if you accidentally touch a hot burner?
Smelling can also be essential in assessing threats. The olfactory system can detect noxious odours, signaling potential dangers (or just someone who ate too much broccoli for lunch).
Our sense of taste can help us reject things we're not supposed to eat like spoiled foods. If you've ever taken a big swig of sour milk, you know what I mean.
The fight-or-flight response is a remarkable testament to the body's ability to adapt and protect itself when faced with potential harm.
But wait. Why are we talking about the 5 senses in an article about silica dust?!
Because it's important. When we don't see, hear, feel, taste, or smell a threat, our body doesn't perceive a danger. When we don't perceive danger, we don't feel the need to do anything to protect ourselves.
The problem is this. Some things are very dangerous but they're invisible threats. We don't see them. They don't make a sound. They don't have a taste. We can't physically feel them. And they don't have an odour.
That's respirable crystalline silica dust (RCS).
Respirable crystalline silica is undetectable by all of our senses. This means that our fight-or-flight response doesn't kick in when we're around it.
Unlike the immediate, instinctual reactions of our sympathetic nervous system, we must rely on behaviour changes (implementing controls, following protocols, wearing masks, etc.) to protect ourselves from silica dust. Changing behavior is a dynamic, complicated process that demands considerable time, dedication, and motivation.
However, it's essential to understand that despite its seemingly innocuous nature, silica dust poses significant risks and can even be deadly.
Keep reading to learn why.
What is Silica?
Silicon Dioxide (SiO2) or simply, silica, is the second most abundant element that makes up the earth’s crust. Most rocks, stones, soil, and sand are composed of silica.
Silica is either non-crystalline (amorphous) or crystalline. Common forms of crystalline silica are quartz (most common), cristobalite and tridymide. Crystalline silica is more toxic than the amorphous form and is largely responsible for the adverse health effects associated with occupational hazards.
When products containing silica are crushed, grinded (errr...ground), drilled, excavated, polished, blasted or mechanically manipulated in any way, very small particles of silica - called respirable crystalline silica (RCS) - are released into the air.
Respirable crystalline silica is really, really tiny. Really tiny things are measured in microns. One micron is 1/1000 of a millimetre.
To put that in perspective, imagine a grain of beach sand. (Or pick up a grain of beach sand if you happen to be kicking back in Whitsundays or taking a stroll down Ninety Mile Beach you lucky duck). A single grain of sand is around 90 microns. By comparison, some dust particles - such as respirable crystalline silica - can be less than 2.5 microns.
This image highlights different particles:
Credit: Virtual Capitalist
Particles less than 10 microns bypass the body's upper airway defenses (coughing, sneezing, mucociliary clearance) and go straight to the lungs.
Particles less than 2.5 microns (which respirable crystalline silica can certainly be) go even deeper. They penetrate into the alveoli (air sacs) and can cross over into the bloodstream causing widespread, systemic effects in the body.
Another property of submicron particles is that they stay suspended in the air - sometimes for hours.
What industries are most affected?
RCS is generated whenever silica-containing substances or products are mechanically manipulated. Credit: Canva
You've probably heard a lot of buzz around silica as it relates to the stone benchtop industry.
That's because stone benchtops are often made from engineered stone, which can contain up to 95% silica. The process of cutting, shaping, polishing, and finishing these materials can generate significant amounts of respirable crystalline silica.
In fact, there's so much emphasis on the stone benchtop industry that some people don't think silica is a problem in other workplaces or industries.
That's not true.
Silica is ubiquitous in many industries and workplaces including:
Construction
Construction workers are at significant risk due to the use of materials like concrete, mortar, stone, and bricks that contain crystalline silica.
Mining and Quarrying
Workers in the mining and quarrying industries are exposed to silica dust when extracting minerals such as coal, gold, or minerals containing quartz.
Manufacturing
Certain manufacturing processes, including foundry work, glass manufacturing, and the production of ceramics, can generate silica dust.
Agriculture
Farmers and agricultural workers may be exposed to silica dust when handling materials like sand, soil, and fertilizers.
Tunneling and Excavation
Workers involved in tunneling, excavation, and underground construction are at risk due to the presence of naturally occurring silica in soil and rock.
Oil and Gas
Activities like hydraulic fracturing (fracking) in the oil and gas industry can generate silica dust from the use of sand as a proppant.
Abrasive Blasting
Workers who engage in abrasive blasting, such as sandblasting, for surface cleaning and preparation are at risk of silica exposure.
Demolition and Renovation
Demolition workers and those involved in building renovation can encounter silica dust when cutting or removing materials like concrete or drywall.
Firefighters
Firefighters may be exposed to silica dust when suppressing fires involving construction materials.
Take Note!
It's important to note that you don't have to be "doing" the work with silica-containing substances to be affected.
Take Joanna McNeill for example. Joanna had a job in adminstration that was located near a quarry. The dust she inhaled over 7 years at her workplace led to the devastating diagnosis of silicosis in her early 30s.
You can read the story here
Joanna is now a staunch and passionate advocate for silica dust awareness and policy change.
How Much is Too Much?
The fact is, no amount of silica dust is safe. But there is guidance on how much is too much in the workplace.
Safe Work Australia developed workplace exposure standards for airborne contaminants to support workplaces that are exposed to dangerous chemicals and particulates.
These workplace exposure standards (shortened to WES), comprise an exhaustive catalog of hazards each linked to a specified maximum allowable exposure.
For respirable crystalline silica, the time-weighted average for an 8-hour workday is 0.05mg/m3. In Victoria, the limit was lowered to 0.025mg/m3. That is less than the speck you see beside this 5-cent coin below.
There's no way to know if you're exceeding the WES unless you undergo air monitoring. Whether or not you have to legally do this depends on the industry you're in and your state/territory regulations.
Some regulatory bodies fall short of saying that air monitoring is a requirement versus a "suggestion" which causes a lot of confusion for PCUBs.
For example, WorkSafe Victoria notes: Employers must carry out atmospheric monitoring for crystalline silica dust generated at their workplace where:
there is uncertainty about whether the exposure standard is or may be exceeded, or
air monitoring is necessary to determine whether there is a risk to employee health
If there is silica dust exposure in any workplace, there will always be uncertainty about whether the exposure standard is or may be exceeded unless air monitoring is conducted. There is no other way to be certain.
PS: We have spoken to WorkSafe Victoria about this conundrum. They advise that silica work must be considered "high risk silica work" if you don't know the air levels.
The bottom line is, keeping an eye on the air quality through atmospheric monitoring is a smart move - whether it's a requirement or not. Without it, it's hard to tell which safety steps are doing the trick and where we might need to make things better.
Silicosis
I'm sure you've heard of silicosis. Silicosis is a debilitating, fatal disease caused by inhaling RCS dust.
Australia has witnessed a growing concern regarding silica dust exposure in recent years. According to Safe Work Australia, from 1986 to 2016, 587 workers died from silicosis, and the number of compensation claims related to silica exposure has risen dramatically.
According to a recent report out of Curtin University, an estimated 584,050 Australian workers are currently exposed to respirable crystalline silica. The report warns that between 83,090 and 103,860 people (out of the 500k+ exposed) will develop silicosis. A truly staggering statistic.
Silica is extremely toxic to the body. It causes irreversible scarring of the lungs. Scarring of the lungs is called 'pulmonary fibrosis.'
The left chest x-ray below shows pulmonary fibrosis caused by silicosis. Those white patches are scar tissue. Oxygen can't be exchanged across the damaged tissue. No oxygen = no life.
The x-ray on the right is a pair of healthy lungs. All of that black space is air. That's what you want to see!
There are 3 types of silicosis:
Chronic (nodular) silicosis, the classic form that develops after low to moderate exposure over around 10 years.
Accelerated silicosis, typically emerges after 1 to 10 years of moderate to high exposure; and
Acute silicosis, which can happen in less than a year of high-level exposure.
Unfortunately, there are no treatments for silicosis and it's often a fatal disease.
Symptoms
It can take years for the symptoms of silicosis to manifest.
In the early stages, the symptoms may be mild and include a persistent cough, increased sputum production, and a gradual onset of breathlessness.
As the severity of lung scarring and damage increases, symptoms get worse. Sufferers experience an ongoing cough, shortness of breath, weakness, fatigue, fever, night sweats, leg swelling, and a bluish tint on the lips (due to lack of oxygen).
RCS is so small that it crosses from the capillaries of the aveoli into the bloodstream
But that's not all.
Because RCS is so small, it crosses from the alveolar capillary membranes into the bloodstream, causing widespread damage to the body.
People with silicosis are at risk of developing tuberculosis, lung cancer, COPD (chronic obstructive pulmonary disease including bronchitis and emphysema), autoimmune diseases (such as rheumatoid arthritis & scleroderma), and kidney failure.
Scleroderma - which can result from RCS - causes hardening and tightening of the skin. It may also cause problems in the blood vessels, internal organs and digestive tract.
Prevention Measures
To mitigate the dangers of silica dust exposure, proactive prevention measures are essential. Most folks who manage workers' health and safety refer to the hierarchy of controls to help mitigate risks.
1. Elimination: Physically remove the hazard. (This is not always feasible or possible).
2. Engineering Controls: Implement dust control methods, like wet cutting, dust extraction systems, and improved ventilation to reduce silica dust .
3. Substitution: When possible, replace or reduce the hazard. For example, choose a product with a lower percentage of silica.
4. Administrative Controls: Change the way people work through education, training, policies, procedures and best practices. Behaviour change is not easy!
5. Personal Protective Equipment (PPE): Ensure the use of appropriate PPE, including respiratory protection (that has been fit tested and the user trained on how to use it appropriately), eye protection, coveralls, and gloves where necessary.
In most scenarios, a combination of elimination, substitution, engineering, administrative protocols, and PPE is required for comprehensive risk management of RCS. This is especially true if a workplace hasn't undertaken air monitoring to assess the extent of the hazard.
Wrapping Up
Silica dust exposure remains a real threat to workers in various industries across Australia and the world. From construction sites to manufacturing facilities, employees encounter the potential dangers of RCS on a daily basis.
Understanding the risks associated with RCS exposure is important. Fatal diseases such as silicosis can have severe and long-lasting consequences for workers, including death.
Implementing preventive measures is equally vital in mitigating these risks. Employers must actively invest in engineering controls, administrative protocols, and personal protective equipment (PPE) to create safer work environments.
The alarming statistics in Australia highlight the pressing need for continued vigilance, awareness, and regulatory efforts to combat this occupational hazard. It is a reminder of the real and ongoing risks faced by workers across our country.
By prioritizing safety, raising awareness, investing in proper protection, and adhering to regulations, we can significantly reduce the impact of silica dust exposure and ensure that workers are protected from respirable crystalline silica.
All workers deserve to be safe at work.
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