Dust

Construction Dust is a general term used to what may be found on a construction site. There are three main types:

• Silica dust – Silica is a natural mineral present in large amounts in things like sand, sandstone and granite. It is also commonly found in many construction materials such as concrete and mortar. The silica is broken into very fine dust (also known as Respirable Crystalline Silica or RCS) during many common tasks such as cutting, drilling and grinding. It is often called silica dust (see also Control of exposure to silica dust: A guide for employees).
• Non-silica dust – There are a number of construction products where silica is either not found or present in very low amounts. The most common ones include gypsum, cement, limestone, marble and dolomite. This dust is also mixed with silica dust when cutting things like bricks.
• Wood dust – Wood is widely used in construction and is found in two main forms; softwood and hardwood. Wood-based products are also commonly used including MDF and chipboard (see also Wood dust).

Anyone who breathes in these dusts should know the damage they can do to the lungs and airways. The main dust related diseases affecting construction workers are:

• lung cancer
• silicosis
• Chronic Obstructive Pulmonary Disease (COPD)
• asthma (see also the Asthma site)

While some of lung disease like advanced silicosis can come on quite quickly, most take a long time. Often this is over years. They happen because during this time regularly breathing even small amounts of dust adds up and damages the lungs and airways. Unfortunately, by the time you notice the damage is often done and it is more difficult to treat.

Many construction tasks create dust. High dust levels are caused by one of more the following:

• equipment – using high energy tools, such as cut-off saws, grinders, wall chasers and grit blasters produce a lot of dust in a very short time
• work method – dry sweeping can make a lot of dust when compared to vacuuming or wet brushing
• work area – the more enclosed a space, the more the dust will build up
• time – the longer you work the more dust there will be

Examples of high dust level tasks include:

• using power tools to cut, grind, drill or prepare a surface
• sanding taped plaster board joints
• dry sweeping

To protect your lungs the Control of Substances Hazardous to Health (COSHH) Regulations (see also COSHH) sets a limit on the amount of these dusts that you can breathe (called a Workplace Exposure Limit or WEL). These limits are not a large amount of dust. To give an example the image below shows the maximum amount of silica you can breathe when averaged over a normal working day.

When compared to a penny it is tiny – like a small pinch of salt:

'This limit is the legal maximum, the most you can breathe after the right controls have been used. For tasks that can create high levels of silica and wood dust these controls have to be very good as the risks from these dusts are high

You should look at ways of limiting the amount of dust you could make before you start work. For example you could:

• use the right size of building materials so less cutting or preparation is needed
• use a less powerful tool – eg a block splitter can sometime be used instead of a cut-off saw - See Block splitting
• using a different method of work altogether – eg using a nail gun to direct fasten cable trays instead of drilling holes first

Even if you can stop some of the dust this way you may need to do other work that could still produce high amounts of dust. In these cases the most important thing is to stop the dust getting into the air. There are two main ways of doing this which both give very good results:

• water – water damps down dust clouds. However, it needs to be used correctly. This means enough water for the whole time that the work is being done.  Just wetting an area of ground before cutting does not work. (see also Using cut-off saws: A guide to protecting your lungs (INDG461) and Time to clear the air! Using cut-off saws for cutting kerbs and flag paving)
• vacuum extraction – specially designed tools can be fitted with an industrial vacuum unit that sucks the dust away as it is being created and stores it until emptied (see also Controlling dust during the refurbishment and extension of occupied premises)

There are a number of things that can happen when using water or vacuum extraction that can stop the dust being properly controlled. Even if this does not happen, some tasks are so dusty that enough escapes into the air to still be a risk. For this reason some form of respiratory protective equipment (RPE), usually in the form of a mask, is also needed for high risk tasks such as:

• using a cut-off saw, grinder or wall chaser on material containing silica
• using powered cross-cut saws and sanders on hardwood, red cedar or MDF
• sanding softwood in an enclosed space

Masks are available that provide different levels of protection. There are two main performance types you should ask your supplier/ employer for if working with construction dusts: FFP2 and FFP3. FFP3 is the most advisable type to use if you are doing work that does or could create high dust levels or involves silica or wood dust (the more hazardous substances).

For more information on masks and other types of RPE see Respiratory protective equipment at work: A practical guide.

Unless there are real problems doing so you should not just rely on a mask for high risk tasks. There are some very good reasons for this including:

• high risk tasks can produce so much dust that the mask cannot give the amount of protection needed -also the filter in a mask can quickly become clogged and stop working.
• a mask only protects the person wearing it - anyone else in the area could still be at risk from the dust if they do not wear a mask as well.
• there are many common mistakes that people make with masks - these include choosing the wrong type, not being face fit tested or not wearing them properly.

As already mentioned the main aim is to stop the dust getting into the air in the first place. If you do just rely on a mask for high risk tasks you may be asked to justify why.

Masks rely on a tight seal with the face to work. This is so that only air going through the filter is breathed. If the mask does not fit properly the dust can slip through any gap between the mask and the face and into the airways. Dust particles can be much smaller than the width of a hair so the face seal needs to be very good.

There are many designs of masks. Not all will fit you well enough to form a good seal with your face. To find one that does you therefore need to be face fit tested. There are two types of test: qualitative and quantitative. Both are acceptable for testing masks used for construction dusts. For more information on face fit testing see the Fit2Fit site.

No. Construction work often involves a number of quick tasks done throughout the day. Some of these tasks can still cause a large amount of dust that over a period of time will still have the potential to harm you. It is important that you try to limit the amount of dust every time you do some work so that the total amount you may breathe in over the years does not build up.

No. People often think that construction dust is not a problem if they are working outside because it will just blow away. While the wind will have some effect on the level of dust many tasks involve the person working close to the part of a tool where the dust is being made. With very dusty tasks this means that they can still breathe a lot of harmful dust

It is very difficult to give an answer that will cover all situations. There are though a few good rules of thumb. If working outside you should stay away from the area around the dust cloud and take care that any wind does not blow this in your direction. If working indoors, this is more difficult as the dust levels will build up. In general it is best to stay away from the area where the dust is until the air is clearer. However, this can take a long time as the fine dust can stay suspended in the air for a long time. The best thing is always to stop the dust getting into the air in the first place. Tell someone in charge that the correct controls are not being used.

No. The risk of lung disease is linked to people who regularly breathe construction dust over a period of time, not on the odd occasion. However, breathing construction dust even over a short period of time is not nice (for example when passing some street works) and could cause a reaction in someone who already has asthma or another existing breathing problem. It therefore should be avoided by using the right controls and making sure that members of the public are not close to the work when it is going on (see also Protecting the public: Your next move).

The Health & Safety Executive does not deal with dust from construction sites where the main concern is that it is a nuisance. The Local Authority Environmental Health Department for the area may be able to assist with this problem.

The section on hazardous substances provides further information on this and related topics.