What Is Silica Dust and Silicosis?

Dust is often overlooked as a potential workplace hazard. Unfortunately, dust contains harmful particles.

When stone or concrete is cut, the particles floating through the air likely contain silica dust. This dust increases the risk of a variety of health issues, including silicosis.

To remain safe, tradespeople and even DIY enthusiasts should know more about silica dust and how to reduce exposure.

So, what is silica? Here is what you should know to protect yourself or your workers from the dangers of this dust. We have known about ‘stone dust disease’ since the Greek and Roman times with it being written about in the 16^th Century by Agriola.

What Is Silica and Concrete Dust?

Silica is silicon dioxide. It is a naturally occurring mineral and a major component of rock and soil. Different types of silica exist, including non-crystalline and crystalline forms of the substance.

Quartz is the most common crystalline silica mineral. Most types of rock and products containing rock contain varying amounts of silica. For example, the composite stone may contain up to 90% silica while granite typically contains 25% to 40% silica.

When workers crush, cut, drill, grind, saw, or polish stone or man-made products containing silica, they release silica dust into the air. The dust particles are incredibly fine. Some are so small that they remain invisible. To see the particles, workers often need to use a beam of intense light.

Respirable crystalline silica (RCS) refers to the fraction of airborne silica dust that poses a health concern due to its microscopic size. The microscopic particles can penetrate deep into the lungs, increasing the risk of silicosis.

What Is Silicosis?

Silicosis is a potentially deadly health condition caused by exposure to silica dust. It is a lung disease that often occurs years after exposure due to the buildup of silica.

When you breathe in the tiny particles, the dust settles in your breathing passages and lungs. The silica particles cause scarring. The scarring stiffens the lungs, making it difficult to breathe.

Besides trouble breathing, people suffering from silicosis may notice the following symptoms:

• Phlegm
• Coughing
• Fatigue
• Weight loss
• Fever
• Swollen legs
• Shortness of breath
• Blue lips

Three types of silicosis exist — acute, chronic, and accelerated. Acute silicosis may present symptoms in a few weeks or a couple of years after exposure to silica. The symptoms develop rapidly after a short exposure.

With chronic silicosis, symptoms may not show up for decades after exposure to low or moderate levels of silica. This is the most commonly diagnosed type of silicosis. The symptoms may appear mild and then slowly progress.

Accelerated silicosis first presents symptoms five to ten years after heavy exposure. The symptoms appear suddenly and then accelerate quickly.

All types of silicosis are serious and potentially fatal. People suffering from silicosis are at greater risk of developing tuberculosis and lung cancer.

Exposure to silica can also lead to chronic airway obstruction and simple chronic bronchitis.

Exposure to Silica dust can also lead to a condition similar to Multiple Sclerosis (Nervous System Damage) called Systemic Sclerosis, scleroderma myositis and related syndrome.

How Long Does Silica Dust Stay in the Air?

Silica dust is incredibly light and can remain airborne for long enough to travel outside of the immediate area. In a confined space without proper ventilation, the particles can accumulate.

PCBUs have a responsibility to maintain a reasonably safe work environment, which includes limiting exposure to health hazards such as silica dust. OHS regulations specify that workplace exposure should not exceed 0.1mg/m3 during an eight-hour work day. To keep track of the levels of silica dust in the air, work sites with a significant presence of silica dust should have air monitoring equipment.

The use of ventilation systems can help reduce the amount of dust in the air. In fact, studies show that local exhaust ventilation can remove up to 99% of the dust in the atmosphere.

Where Is Silica Dust Found?

Silica dust is found in a wide variety of common masonry and construction materials, including:

• Concrete
• Stone
• Bricks
• Tiles
• Gravel
• Sand
• Clay
• Soil

Some glass and plastic materials also contain small amounts of silica. Crystalline silica is extremely tough and temperature-resistant, making it a suitable ingredient in a variety of products.

Cutting, grinding, or demolishing materials that contain silica releases the dust into the air. It is fine dust 100 times smaller than a single grain of sand. The particles are so small that they may remain undetected.

Quartz is the most commonly found type of crystalline silica, comprising 12% of the Earth’s crust. Any activity that involves mining or quarrying involves silica and the resulting dust.

Sand and sandstone contain the highest amount of crystalline silica. These materials contain between 96% and 100% silica while demolition dust contains 3% to 4% silica.

What Is the Best Respirator/PPE for Avoiding Silica Dust?

The use of personal protective equipment (PPE) is one of the recommended solutions for reducing exposure to silica dust. This typically involves the use of a respirator to help filter particles from the air.

Respirator masks receive ratings based on the assumed protection factor (APF) and the occupational exposure limit (OEL). The standard ratings include P1, P2, and P3.

SafeWork Australia recommends that workers be clean shaven and wear a minimum of a P2 efficiency respirator mask. Workers should also wear clothing that does not promote the collection of dust particles.

Besides respirator masks and appropriate clothing, the use of ventilation systems, water suppression, and tools with dust collection equipment help reduce exposure.

In some cases, PCBUs or supervisors need to implement shift rotations / modify cutting sequences / have extraction at source equipment to help limit the presence of dust particles in the air.

Silica dust is a major concern when working with materials containing crystalline silica. To limit exposure and the health risks related to silica, ensure that your workplace complies with WHS / OSH legislation, including the use of the hierarchy of controls.