Cutting bricks and blocks, and the dust

Building work often means cutting a few bricks, blocks or slabs to fit. A cut-off saw does it quickly, and it throws up a lot of fine dust in a very short time. This page sets out what the Health and Safety Executive (HSE) expects when you cut masonry.

Why the dust is harmful

HSE says bricks, tiles, concrete and mortar all contain silica. Cutting, drilling and grinding them makes dust, and some of it is fine enough to get deep into the lungs. HSE calls this fine dust respirable crystalline silica, and says it is too fine to see in normal lighting.

HSE says silica is the biggest risk to construction workers after asbestos. Heavy and prolonged exposure can cause lung cancer and other serious respiratory diseases. HSE also links it to silicosis and to chronic obstructive pulmonary disease (COPD).

How many people it harms

HSE says over 500 construction workers are believed to die from exposure to silica dust every year. Most of these diseases take a long time to develop. HSE adds that by the time anyone notices, the damage may already be serious and life changing.

Less cutting, then control at the blade

HSE's information sheet on construction dust starts with making less of it. A builder can order materials in sizes that need fewer cuts, or use a block splitter instead of a cut-off saw. HSE also suggests having material cut off site and delivered.

Where the cutting goes ahead, HSE names two main ways to stop the dust getting into the air. The first is water. HSE says the saw needs enough water at the right level for the whole time the work is done, and that wetting the material beforehand does not work.

The second is on-tool extraction, which takes the dust away as the tool makes it. HSE says to use an extraction unit with an H, M or L class filter, and not a general commercial vacuum.

Then the mask

For cutting blocks, kerbs and paving with a cut-off saw, HSE's table pairs water suppression with respiratory protective equipment (RPE). The general level it gives for construction dust is an assigned protection factor of 20. That means the wearer breathes only one twentieth of the dust in the air.

HSE says the mask has to fit the person wearing it. Tight-fitting masks need a face fit test, and the wearer needs to be clean shaven. HSE calls RPE the last line of protection.

The law behind it

The Control of Substances Hazardous to Health Regulations 2002 (COSHH) cover work that may expose people to construction dust. HSE puts the duty in three steps. Assess the risks, control them, then review the controls.

The saw itself is work equipment under the Provision and Use of Work Equipment Regulations 1998 (PUWER). HSE says the people who own, operate or have control over work equipment have duties under them. The equipment must be maintained in a safe condition, and used only by people with adequate information, instruction and training.

Using a disc cutter also brings a risk of hand-arm vibration. HSE lists disc cutters among the tools that can damage the nerves, blood vessels and joints of the hand, wrist and arm. It says that once the damage is done, it is permanent.

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