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Feature on health - the risks of dust

It is often said that "Health" is the poor relation in Health and Safety. This is evident when you consider the effort and resource that is put in to managing safety on site compared to health related issues such as dust, manual handling, noise, vibration and exposure to hazardous substances.

Health statistics tell their own story

When you look at the statistics, it should come as no surprise that the HSE have now pushed health right to the top of their agenda. In the year 2012-13, 39 people died in accidents working in construction. In the same period:

  • more than 2,500 construction workers died from previous exposure to asbestos
  • more than 500 died from previous exposure to silica.
  • there were 74,000 reported cases of ill health.
  • an estimated 9 million days lost due to manual handling injures.
Sources of dust risks

The sources of dust on site are varied and include wood dusts, concrete, brick and plaster dusts, and general construction dust which is a combination of the above combined with dust produced from dry ground conditions. Some dusts have well known serious health implications for example asbestos dust, other dust such as that caused by sweeping out a plot can also cause significant irritation and breathing problems.

Whatever the type of dust we need to takes steps to reduce exposure. Some substances such as asbestos, silica dust and wood dusts have workplace exposure limits set down in regulations requiring employers to manage exposure below these levels. Such is the problem that the management of exposure to dust is high on the HSE's priority list for enforcement this year.

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Respirable Crystalline Silica (RCS)

Probably the most serious issue in house building (where exposure to asbestos is unusual) is that caused by Respirable Crystalline Silica dust (RCS). Many natural rock, clays and sands contain large amounts of crystalline silica and are used to make kerbs, flags, bricks, tiles and concrete.

Cutting, drilling and chasing these materials produces airborne dust containing very fine RCS particles. These particles are extremely small (normally invisible to the naked eye). The particles are so small in fact that they can penetrate the deepest part of the lungs where they will remain indefinitely. The silica in your lungs causes stiffening and scarring of the lungs called silicosis. This condition can make the affected person so breathless that they become disabled. Silicosis also increases the risk of serious lung infections such as tuberculosis (TB). Every year there are over 500 silica related deaths and this is just one of the many problems caused by exposure to dust.

Avoiding the risks of dust

As with all risks it is best if we can avoid them altogether. Visiting a site recently the site manager proudly told us that the bricklayers had had to cut all the sandstone facing blocks to fit around all the windows; this was hundreds of blocks, hundreds of cuts and a huge potential exposure to RCS. By getting designers to think about these problems early in the design process many issues can be designed out or specified for offsite manufacture.

Managing the risks of dust

There will, however, always be a place for the onsite cutting, grinding chasing, breaking out and other operations that produce high exposure to dust, what steps can we take to manage this?

There are alternatives to cutting which produce far less dust. For example, there are various proprietary roof tile cutters available that split the roof tile accurately with virtually no dust and brick and block splitters are also relatively common on site. However currently, the most common tool used for cutting brick, block and concrete on site is the cut off saw which produces a huge amount of dust if not controlled properly.

Water suppression

For petrol saws the most common control system is water suppression. Water is either mains fed or pumped from a bottle to provide a flow of water on to the cutting area damping down the dust. To be effective the flow of water needs to be about 0.5 litres per minute so you need to consider the proximity of the water supply, how often water tanks will need to be refilled and who will pump the water tank to keep it pressurised. Failure to consider these things often leads to water running out while the cutting continues as refilling water tanks can be time consuming and difficult especially if you are working on the top of a scaffold.

Local Exhaust Ventilation (LEV)

With electric cutting, grinding and sanding tools you need to use dust extraction either with an integrated filter bag on cordless tools or, ideally, with a mains vacuum Local Exhaust Ventilation (LEV) system fitted directly to the tool. The latter is being seen increasingly on site being used with chop saws and sanders.

It is important that the right type of vacuum is used, a normal commercial vacuum (even with a HEPA filter) will not remove the smallest dust particles, all vacuums used should be labelled as a (H)igh or (M)edium class unit. All dust extraction systems need to be maintained regularly as filters quickly get blocked. There should be a formal inspection at least once a week and vacuum systems need a formal Thorough Examination and Test at least every 14 months. This is a formal and systematic examination of the equipment by a qualified person to ensure it is working efficiently. If the equipment is hired you should request confirmation that this test has been undertaken.

Respiratory protective equipment (RPE)

Even with dust extraction or suppression being used, the exposure to dust can still be high as if they're not working to their full capacity because of poor maintenance. Because of this it is important to ensure that those undertaking and those in close proximity to these tasks are wearing the appropriate respiratory protective equipment (RPE).

The job of RPE is to ensure the air that is inhaled has had the contaminants effectively removed by filters. The Personal Protective Equipment Regulations require the employer to ensure any PPE that is required is fit for purpose and fits the wearer. For RPE this means ensuring that the type of RPE used is suitable for both the type of contaminant, the level of exposure, the duration and type of use and the person wearing it. There is no such thing as one size fits all! Everybody's face is a different shape and size and in the same way you wouldn't wear safety boots that were too big or too small you must not wear RPE that has not been fitted properly. RPE only works if all the air entering the nose and mouth has been filtered. Poorly fitting RPE will allow contaminants to pass through gaps between the face and the mask, or will make it so difficult to breath that wearing the mask will become impossible. Face fit testing will help ensure that the equipment selected is suitable for the wearer.

Face fit testing

Face fit testing matches the wearer with RPE that fits correctly and provides suitable protection for the work they will be doing. It should also take into account other PPE that has to be worn and the duration of the work. Employers should use a trained fit tester, many PPE suppliers now offer this service either directly or can train your own staff as fitters - look for companies accredited to the Fit2Fit Scheme. For the most common types of RPE used on building sites wearers of RPE will need to be clean shaven. One size and type will not fit, or be suitable, for all so you will need a range of RPE.

The type of RPE worn depends on the task being undertaken. The most common disposable face fitting masks seen on site are only one option and for work where RPE will need to be worn for more than an hour at a time alternatives should be looked into such as air fed RPE which is much more comfortable to use.

In order to protect against the smallest dust particles like RCS you need a filter fine enough to catch these particles. For all tasks where there is a risk of exposure to RCS a P3 filter should be used - for standard disposable masks this will be an FFP3 mask. Masks that are not marked as such do not provide adequate protection. Where the risk is of exposure to lower hazard dusts such as gypsum and wood dusts an FFP2 mask would be sufficient.

Health surveillance

And finally, for those workers who are regularly exposed to high levels of dust there may well be a requirement for health surveillance. This need not be onerous but safeguards both the employee and the employer by ensuring work activities are not having long term detrimental effects on those working on site.