Crystalline silica dust – the health hazards and how to recognize them

The inhalation of dust containing quartz particles (crystalline silica) is a recognized health hazard, which, among other things, can lead to the fatal occupational lung disease Silicosis (commonly known as “grinder’s asthma”). Examples where the silica dust occurs include quarrying, the sand-, gravel-, and mining industry, foundries, asphalt, the manufacturing of glue, paint and plastic as well as steel and metal processing. Symptoms of silicosis include cough, fever, shortness of breath and cyanosis (bluish skin).

What is silicosis?

Silicosis is caused by the exposure and inhalation of silica, which is created from working with, or more accurately, the cutting or grinding of stone and rock or working with sands and clays. Working with these materials creates a very fine dust, known as RCS (respirable crystalline silica), that without adequate control, is easily inhaled.

Once inside the lungs, RCS will cause inflammation and eventual irreversible hardening and scarring of lung tissue, which creates long term respiratory problems.

What are the symptoms of silicosis?

The main symptoms of silicosis are a persistent cough, shortness of breath and fatigue. These symptoms are also known to become more severe, impacting quality of life, potentially becoming life threatening with development of tuberculosis (TB), pulmonary hypertensions, chronic obstructive pulmonary disease (COPD) and lung cancer.

Silicosis can develop after prolonged exposure to RCS for 10-20 years, but symptoms can develop after 5-10 years. Acute silicosis, while rare can happen after short-term exposure to large amounts of RCS.

For a full list of symptoms, see below:

Early symptoms of silicosis

• Dyspnoea (shortness of breath) exacerbated by exertion
• Cough, often persistent and sometimes severe
• Fatigue
• Tachypnoea (rapid breathing)
• Loss of appetite and weight loss
• Chest pain
• Fever
• Gradual darkening of skin (blue skin)
• Gradual dark shallow rifts in nails eventually leading to cracks as protein fibres within nail beds are destroyed

Advanced symptoms of silicosis

• Cyanosis, pale along upper parts of body (blue skin)
• Cor pulmonale (right ventricle heart disease)
• Respiratory insufficiency

What natural and engineered materials contain crystalline silica?

Crystalline silica is a variant of silica that contains a well-defined crystal structure. Crystalline and non-crystalline silica exist, with crystalline silica being the hazardous form. Below is a list of primary natural sources and engineered materials that contain crystalline silica:

Natural sources

• Quartz - The most common form of crystalline silica.
• Sand – Most sand, particularly beach and desert sand, consists of quartz.
• Granite – Contains a large amount of quartz.
• Chert and flint – Natural materials composed of micro crystalline quartz.

Engineered materials

• Concrete – More often than not contains crystalline silica in the form of quartz.
• Abrasives – Silica sand based abrasives are often composed of quartz.

Who is susceptible to silicosis?

Occupations where you would be most commonly exposed to the risk of silicosis are:

• Construction – demolition, renovation, masonry work and concrete mixing.
• Quarrying and mining – coal mines, metal mines and stone quarries.
• Foundries and metalworking – casting and metalworking.
• Ceramics and pottery – material handling.
• Stone cutting and fabrication – cutting, grinding and polishing of stone.

Dusty environments are a major problem in the construction industry and measurements have shown that many construction sites exceed the limit for silica dust. Workers who deal directly with concrete indoor might protect the respiratory tract with a mask, but what about the colleague standing a few meters away?

They are also exposed to the harmful dust.

It is estimated that over 500,000 workers in the UK construction industry are exposed to silica dust

What can be done to reduce the risk of silicosis?

All workplaces that work with materials that generate RCS should have stringent control methods in place, and health monitoring as well as regular training and educating of staff to make them aware of the risks involved and to ensure best operating practices when working with RCS generating materials. There is a workplace exposure limit (WEL) that contains exposure below a set limit to prevent excessive exposure. Currently it is 0.1 mg/m3 as an 8-hour time weighted average (established by the HSE). These exposure limits are and should be controlled by wet systems and local exhaust ventilation to reduce the spread and collect the generated RCS before it can be inhaled by the operator and others working in vicinity. Filtering facepieces and respiratory PPE is also advised, not only as a regulatory requirement, but to reduce the chance of exposure significantly.

Chronic silicosis may take years to develop. That’s why the signs might not appear until years after exposure. Silicosis is a major concern in the UK, especially in industries that have high silica exposure. Taking action for your worker’s environment early could therefore save lives!

To discuss how we can help maintain clean air in your workplace, and protect the health of you and your employees, please contact us.