What Is Silica Dust And Why Is It Bad For You?

Silica dust is a big problem, especially in construction work.

The HSE estimated silica dust was responsible for around 500 construction worker deaths in 2005, but this number is likely to be just the tip of the iceberg. Silicosis is not currently a RIDDOR reportable disease. Under-reporting is also likely because it's difficult to know the exact cause of your lung problems when they develop so many years after exposure.

Silica is the biggest risk to construction workers after asbestos. Heavy and prolonged exposure to RCS can cause lung cancer and other serious respiratory diseases. HSE commissioned estimates it was responsible for the death of over 500 construction workers in 2005.

Even with such a high level of fatalities, many construction workers are unaware of the risks. And when they cut into kerbing, paving and other concrete, stone or masonry materials, harmful silica particles are released.

What is silica dust?

Silica is one of the most abundant elements on Earth, second only to oxygen. It is a mineral (silicon dioxide) found in sand and soil. Many forms of silica exist, and you may find it in water, food, toiletries and other products.

And silica itself is not the problem. But silica dust is.

Silica dust is the fine particles of a type of silica known as crystalline silica. You can find this type of silica in stone, rocks, sand and clay. When these materials are disturbed, they release dust that is dangerous to inhale. When we talk about silica dust, we are referring to crystalline silica.

In many ways, silica-containing construction products are like asbestos-containing construction products.

Silica is also a naturally occurring material, and the products containing it are not harmful unless disturbed.

Many building products, including concrete, tiles, cement products and clay bricks, contain silica. Silica is a primary component in sand and rocks like sandstone and granite.

Silica dust gets created when these building products are cut, drilled or otherwise worked on. These activities release fine particles called respirable crystalline silica (RCS). This crystalline form of silica dust, when breathed in, can cause health problems which we cover in the next section of this post.

Different building products can contain different levels of silica. Here are some approximate percentages of silica content (based on Health and Safety Executive data).

• Sandstone: 70-90%
• Plastic Composites: 20-90%
• Concrete/Mortar: 25-70%
• Shale: 40-60%
• China Stone: Up To 50%
• Granite: 20-45%
• Tile: 30-45%
• Slate: 20-40%
• Brick: Up To 30%
• Ironstone: Up To 15%
• Basalt/Dolerite: Up To 5%
• Limestone: Up To 2%
• Marble: Up To 2%

High-risk activities include tunnelling and excavation work, road building, demolition work and explosive blasting work, and also work in slate, granite cutting and glass manufacturing industries, brick making and some manufacturing processes.

And these are all activities that happen in construction work and associated industries.

Why is silica dust bad for you?

Now you know what silica dust is and where to find it, but why do you need to know about silica dust at all?

Because, unfortunately, silica dust is harmful to your health. It can cause lung problems and a silica specific disease called silicosis. Crystalline silica is classified as a group 1 carcinogen, meaning it causes cancer in humans.

Silica dust can cause lung problems such as:

• Inflammation of the lung tissue
• Silicosis
• Bronchitis
• Lung cancer

None of which are very pleasant, and can shorten your breath and your life.

Silica dust is only harmful when it is inhaled deep into your lungs. But when silica-containing products are drilled, cut or otherwise disturbed, the fine particles released are so small that they float in the air and can easily end up in your lungs.

The silica dust particles are so small you can't even see them.

Research suggests that in Britain nearly 800 people die a year from lung cancer caused by breathing in silica dust at work. In the European Union, around 7,000 cases of lung cancer are caused by this carcinogen annually.

What is silicosis?

You have probably heard of lung cancer, but what is silicosis? If you're thinking... "it sounds like silica", you would be right. Silicosis combines the words silica and osis (meaning disease). In simple terms, it means silica disease.

The development of silicosis is directly related to exposure to silica dust. And similar to asbestos-related lung diseases, silicosis can remain free of symptoms for 10-20 years after exposure.

Silicosis causes damage to lung tissue leading to breathing problems, and it also puts those affected at greater risk of developing lung cancer.

There is no medical treatment for silicosis.

In the chronic form of the disease, symptoms develop over time, and the illness is usually caused by prolonged exposure to silica dust.

In the acute form of the disease, the illness develops quickly due to exposure at high levels. It can lead to a rapid progression of breathlessness and death within months.

Reducing silica dust risks

Exposure should be prevented where possible through the substitution of materials to eliminate the risk.

But you will find silica in many building products that we use every day, including bricks and concrete. It's hard to avoid. So what can you do to protect the health of construction workers?

When you can't eliminate silica, you need to control the dust. The main aim is to stop the dust from entering workers lungs.

You can control silica dust exposure through dust suppression techniques or local exhaust ventilation. These controls are the best because they remove the dust and protect everyone in the environment.

As the last line of defence, workers should wear appropriate personal protective equipment (PPE) and respiratory protective equipment (RPE) at all times when dealing with silica dust. A high level of training and supervision will be required to ensure its proper use.

Think about how the dust can travel too. It could settle on surfaces and become airborne again. Workers could take dust home to their families if it contaminates their clothing and hair.

Provide protective clothing for workers to wear to prevent contamination of their clothing. Welfare facilities for washing and changing should be available on your site.

Make sure workers hands get washed before eating, drinking, smoking or going to the toilet. And these activities should take place away from the contaminated area.

Small changes can make a big difference when it comes to silica dust. And prevention is better than cure because there is no cure.

You can't reverse the health damage caused by silica dust, but you can prevent it.

Silicosis is the most common chronic occupational lung disease worldwide, estimated to affect thousands of workers every year. It is, however, entirely preventable.

Legal requirements

Did you know that there are legal limits for the amount of silica dust you get exposed to at work? Silica dust has a workplace exposure limit (WEL) of 0.1 mg/m3, expressed as an 8-hour time-weighted average (TWA).

And silica dust is a hazardous substance, so COSHH applies. That means you must assess, control and reduce the risk.

Exposure should be as low a reasonably practicable and at least below the WEL.

Find out more about the legal limits in Silica Dust Exposure Limits, Regulations And The Law.

Workers regularly exposed to respirable crystalline silica (RCS) should also have health surveillance. This surveillance can include a respiratory questionnaire, lung function testing and chest X-rays.

But even though there are laws around exposure and a high number of deaths, awareness of the risks and compliance is poor. People are still exposed to high levels of silica dust every day.

A recent study by IOSH estimates that with better compliance the number of deaths from silica-related lung cancer could be reduced by over 75%.

Silica lung cancer cases in Britain could drop to 100 a year if we improve legal compliance.

The HSE regularly arranges events to raise awareness of the dangers of silica dust. However, many in the construction sector still appear unaware of this site hazard.

With many workers and management in the industry unaware of the risk, it's important to spread the message to anyone you work with and make sure they know the risks.

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Make sure your team know about the invisible hazard on your sites by giving a silica safety talk. If you need help preparing your talk, you can download the silica dust toolbox talk to use as a handout.