Silica Dust Exposure: Silicosis Warning Signs and Risks

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Silica dust exposure happens when you breathe in the very fine dust created by cutting, drilling, grinding or polishing stone, concrete, brick and similar materials. Over time that dust scars the lungs and can cause silicosis, lung cancer and chronic obstructive pulmonary disease (COPD). The main warning signs of silicosis are a cough and shortness of breath that will not go away, and weakness and tiredness, but they usually take years to appear, so prevention matters far more than spotting symptoms.

Silica is a hazardous substance controlled under the COSHH Regulations. Our COSHH Awareness course page explains how we help site teams and supervisors understand those duties and control the risks.

What is silica dust?

HSE explains that silica is a natural substance found in most rocks, sand and clay, and in construction materials such as bricks, tiles, concrete and mortar. When you work on these materials, some of the dust produced is fine enough to get deep into your lungs. This fine dust is called respirable crystalline silica (RCS). According to HSE, it is too fine to see with normal lighting, which is why a job can look clean and still be harmful.

HSE describes silica as the biggest risk to construction workers after asbestos, and its construction dust guidance states that over 500 construction workers are believed to die from exposure to silica dust every year.

How much silica is in common materials?

The amount of silica varies a great deal between materials. These figures come from HSE guidance on silicosis:

Material	Silica content
Sandstone, gritstone, quartzite	More than 70%
Concrete, mortar	25% to 70%
Shale	40% to 60%
Slate	Up to 40%
Brick	Up to 30%
Granite	Up to 30%
Limestone, chalk, marble	Up to 2% (but these can contain silica layers)

Warning signs of silicosis

The NHS lists the main symptoms of silicosis as:

a persistent cough
persistent shortness of breath
weakness and tiredness

The NHS also explains why these signs are easy to miss:

Silicosis usually develops after 10 to 20 years of exposure, although it can develop after 5 to 10 years, and occasionally after only a few months of very heavy exposure.
You may not notice any problems until after you have stopped working with silica dust.
The symptoms can continue to get worse even when you are no longer exposed.

HSE adds that the damage is irreversible. People with advanced silicosis may find it difficult or impossible to walk even short distances or climb stairs. Workers with silicosis also have a higher risk of tuberculosis, kidney disease and arthritis, and silica exposure can cause COPD, whose symptoms are a chronic cough, sputum production and breathlessness. If you think you may have been exposed and have any of these symptoms, see your GP and tell them about your work history.

Who is at risk from silica dust?

HSE lists occupations with exposure to RCS, including quarrying, slate works, foundries, potteries, stonemasonry, and construction when cutting or breaking stone, concrete or brick. The NHS also highlights worktop manufacturing and fitting, sand blasting, and mining. On a building site, the people most likely to be exposed include:

Workers using cut off saws, grinders and grit blasters, which HSE describes as high energy tools that produce a lot of dust in a very short time
Anyone chasing walls, drilling or breaking concrete and masonry
Stonemasons and people cutting, fitting or polishing stone
Labourers and other trades working nearby, especially indoors or in enclosed areas where dust builds up

HSE construction information sheet CIS36 explains that the risk rises with the energy of the task, how enclosed the work area is, how long the work takes and how often it is repeated. Do not assume dust levels are low just because you are working outside.

The workplace exposure limit for silica

In Britain, respirable crystalline silica has a workplace exposure limit (WEL) of 0.1 mg/m³ expressed as an 8 hour time weighted average, as set out by HSE. That is a very small amount: HSE shows the most a worker should breathe in a day, after using the right controls, as a tiny quantity next to a penny. Exposure to RCS is also subject to the COSHH Regulations, so employers must assess and control it rather than simply aim for the limit.

HSE also says health surveillance must be provided for workers who are regularly exposed to RCS where there is a reasonable likelihood that silicosis may develop, and should be considered in high risk occupations including construction.

How to control silica dust on site

CIS36 sets out three steps under COSHH: assess the risks, control the risks and review the controls. The control measures include:

Stop or reduce the dust. Use materials cut to the right size, a less powerful tool such as a block splitter instead of a cut off saw, or a different method of work.
Water suppression. Enough water supplied at the right level for the whole task. Wetting the material beforehand does not work.
On tool extraction. A form of local exhaust ventilation fitted to the tool, using an extraction unit with the correct H, M or L class filter, not a general commercial vacuum.
Respiratory protective equipment (RPE). The general level for construction dust is an assigned protection factor of 20. RPE is the last line of protection and must fit the wearer.
Other controls. Limit the number of people near the work, rotate workers, enclose the work with sheeting and choose work clothes that do not hold dust.

CIS36 makes the point that face fit testing is needed for tight fitting masks, and that anyone using one needs to be clean shaven. A mask that does not seal properly lets dusty air leak in around the edges. Our Face Fit course is a one day course, run by a fit2fit accredited assessor, for people who want to run their own face fit testing programme, covering the selection, use and maintenance of RPE, fit test protocols and practical testing. For the wider kit that goes with RPE on site, see our guide to 5-point PPE.

For hazardous products that come with a supplier label, our guide to COSHH hazard symbols explains what each of the nine CLP pictograms means.

Understanding your COSHH duties with Target Zero

Our COSHH Awareness course helps your team identify hazardous substances in the workplace, including by products of work such as dust and fumes. It covers immediate and long term health hazards, effective COSHH assessments, personal protective equipment, health screening programmes, safe handling techniques and the basic COSHH legal requirements.

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FAQs

What are the first signs of silicosis?

The main symptoms are a persistent cough, persistent shortness of breath, and weakness and tiredness. They usually develop slowly and may only appear after you have stopped working with silica.

How long does it take for silica dust to affect you?

Silicosis usually develops after 10 to 20 years of exposure, sometimes after 5 to 10 years, and occasionally after only a few months of very heavy exposure.

Is silicosis curable?

No. The lung damage cannot be reversed, which is why controlling the dust at source is so important. Treatment aims to relieve symptoms and improve quality of life.

What is the workplace exposure limit for silica dust?

The WEL for respirable crystalline silica is 0.1 mg/m³ as an 8 hour time weighted average.

Does a dust mask protect against silica dust?

Only if it gives enough protection, fits the wearer and is worn correctly. HSE gives an assigned protection factor of 20 as the general level for construction dust, and tight fitting masks need a face fit test and a clean shaven wearer.

Which jobs have the highest risk of silica exposure?

Quarrying, stonemasonry, foundries, potteries, worktop manufacturing and fitting, sand blasting, and construction tasks that cut, drill, grind or break stone, concrete or brick.

Silica dust is invisible, but its effects are permanent. Give your team the knowledge to control it: see dates and details on our COSHH Awareness course page, or call 0333 444 0018 to talk to our team.