1.23 Working at Height

Working above ground level.

Basic hazards of work above ground level, including fragile roofs,

deterioration of materials, unprotected edges, unstable/poorly maintained access equipment, weather and falling materials.

Main precautions necessary to prevent falls and falling materials, including the use of guard rails, fencing, toe boards, platforms, ladder hoops, access boards and fall arrest harnesses.

Requirements for head protection. Safe working practices for common forms of access equipment,

including scaffolds (independent tied and mobile tower), mobile elevating work platforms and ladders.

Inspection requirements for scaffolds.

Falls account for a great number of accidents in the construction industry. 50% of those killed are due to falls from a height. All too often, the correct equipment may have been provided but not properly used.

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1.23.1 Working at Height Continued

The safety rules you might consider for the prevention of falls would include:

No work at height unless it is essential.

if work at height is unavoidable, ensure that the working platform, of whatever type, is safe and secure, checking that:

it is strong enough to support the weight of the worker(s) and any equipment that they may be using;

it is stable and will not overturn (for example: all types of scaffolding needs to be tied to a supporting structure) the ground is stable and will support the structure;

guard-rails and barriers are provided at all openings on floors, close to edges on roofs on working platforms.

On a recent inspection of the demolition of a large factory, an inadequate barrier was observed. The workers were dismantling conveying machinery and had to first remove the handrails to the side of the walkways to gain easy access.

Rope across a fall hazard.

The fall was more than 30cm.

There is no intermediate rail and no warning signs.

It should go without saying that this is not suitable fall prevention.

The workers on this job explained that the duration of the work was only going to take a day, and that they had been careful. However, a fall can take

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just seconds and falls from a height kill many construction workers each year.

1.23.2 Edge Protection

Both the edge and any openings need to be protected. It will often be more appropriate to securely cover openings rather than put edge protection around them.

Any protection should be:

in place from start to finish of the work; strong enough to withstand people and materials falling against it.

Where possible, the edge protection should be supported at ground level, e.g. by scaffold standards, so that there is no obstruction. If the edge is too high for this, the sounding structure can support the edge protection provided it is strong enough.

Edge protection can also be supported by frames, counterweights or scaffolding. The protection should be in place at all times. Guarding systems are widely available that enable repair work or alteration to carry on without removing any guard rails.

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1.23.3 Demarcating Safe Areas

Full edge protection may not be necessary if limited work involves nobody going any closer than 2 m to an open edge.

In such cases, demarcated areas can be set up, outside which nobody goes during the work or access to it. Demarcated areas should be:

limited to areas from which nobody can fall; indicated by an obvious physical barrier (full edge protection is not

necessary but a painted line or bunting is not sufficient); subject to tight supervision to make sure that nobody strays outside

them (demarcation areas are unacceptable if this standard is not achieved).

1.23.4 Short-Duration Work'Short duration' means a matter of minutes rather than hours. It includes such jobs as brief inspections or adjusting a television aerial etc.

Appropriate safety measures are essential.

It may not be reasonably practicable to provide edge protection during short-duration work. In such cases, anyone working nearer than 2 m to any unguarded edge should be using a safety harness.

Where safety harnesses are used they need to be:

appropriate for the user and in good condition - full harnesses are essential, safety belts are not sufficient;

securely attached to an anchorage point of sufficient strength;

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fitted with as short a lanyard as possible that enables wearers to do their work;

actually used - tight management discipline is needed to ensure this.

1.23.5 Guard Rails and Toe- Boards

These should be provided whenever someone can fall more than 2 meters and should be made from material both strong enough to prevent people from falling off and to withstand other loads likely to be placed against them - bricks and the like.

If the risk comes from falling through openings or fragile material such as asbestos roofing or roof lights, an alternative to guard rails or a barrier is to cover the opening or fragile material with something more robust.

An associated function of toe boards is to prevent tools and materials from inadvertently being kicked off the side

and this will apply to work at height or work above excavations.

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1.24 Selection of Work Platforms

A work platform is the place where people stand whilst working. It is clearly essential to give thought to the type of platform to be used; the choice is wide and includes:

scaffolding (including fixed general access scaffolding and tower scaffolding);

mobile elevating work platforms (MEWPs); temporarily suspended access platforms and cradles which may be

suspended from the building itself or from a separate crane.

In the latter category we might include sizeable suspended platforms capable of supporting several men and their equipment through to Boatswain's (bosun's) chair (the smallest type of platform) and various rope access techniques e.g abseiling which could be appropriate for inspection purposes.

Those responsible for managing the site need to consider:

The length of time that the equipment is to be in use. Any risks to personnel during the building of the structure. Any maintenance problems if the platform will be up for a long period

of time. How many people will be using the equipment, and how often. Any problems securing the equipment to prevent the possibility of

intruders, particularly children, climbing up. At what stage in the construction programme the work platform will

be bought into use.

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1.24.1 Safety of Working Platforms

Working platforms should be

adequately supported and provided with guard rails or barriers and should be:

wide enough to allow people to pass safely and use any equipment or material needed for their work;

free of any openings or traps through which people's feet could pass; constructed so as to prevent material falling through; in particular, if

there is a wire mesh floor, the mesh should be fine enough to prevent materials, especially bolts and nails, from falling through;

kept free of tripping and slipping hazards; kept clean and tidy.

In this section, we have looked briefly at the general safety aspects of work platforms. We will now turn to look in more detail at the various types of platform:

General access scaffolds and tower scaffolds. Mobile elevating work platforms. Temporarily suspended platforms and cradles. Boatswain's chairs and rope access techniques.

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What about ladders? They are not to be seen as another form of work platform (apart from short-term light work). Ladders are a means of accessing work platforms.

1.24.2 General Access Scaffolds and Tower Scaffolds

General access scaffolds.

Any scaffold must be planned, erected, altered, dismantled and checked by persons who have the appropriate competence.

It is vital to ensure that the scaffold, of whatever type is:

based on a firm, level foundation, taking care of basements, drains, or patches of soft ground, which could collapse when loaded;

braced and tied into a permanent structure or otherwise stabilised; Capable of supporting loads likely to be placed on it.

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1.24.3 General Access Scaffolds and Tower Scaffolds ContinuedThe illustration below shows putlog scaffolding, which uses a series of putlogs (see figure) to support the scaffold and hold it securely.

NEBOSH do require that you know the meaning of some of the structural terms used in scaffolding:

standard , toe board , sole plate/board, transom , ledger,

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(zig-zag) bracing, working platform, guard rail .

Whether the scaffold is independent, tied or putlog or a combination of these, it is essential to ensure that:

platforms are fully-boarded and wide enough for the work and for access;

scaffold boards are properly supported and not overhanging excessively;

there is a safe ladder or other means of access to the work platform.

The illustration above shows an independent tied scaffold:

independent: the scaffold is a complete structure in its own right; tied: the scaffold is firmly attached to the building by making use of

openings such as doors and windows.

This type of scaffold will probably be used for work on an existing building - the scaffold being erected alongside the building and holding on very firmly via the ties.

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1.24.3.1 Video: Introduction to Scaffolding (Basic Terms)

This video was produced by the HSE and covers basic terminology

1.24.4 Tower Scaffolds

Introduction.

Tower scaffolds are widely used and are involved in numerous accidents each year. These usually happen because the tower is not properly erected or used. Aluminium towers are light and can easily overturn. Towers rely on all the parts being in place to ensure adequate strength. They can collapse if sections are left out.

Erecting the tower.

A wide range of prefabricated towers are available. The manufacturer or supplier should provide an adequate instruction manual which should give advice on the erection sequence and bracing requirements. If the tower has been hired, the hirer should provide this information. This information should be passed on to the erector.

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The person erecting the tower should be competent.

Stability.

Make sure the tower is resting on firm level ground with the wheels or feet properly supported. Do not use bricks or building blocks to take the weight of any part of the tower.

The taller the tower, the more likely it is to become unstable. As a guide, if towers are to be used in exposed conditions or outside, the height of the working platform should be no more than three times the minimum base dimension. If the tower is to be used inside, on firm level ground, the ratio may be extended to 3.5. Using this guide, if the tower base is 2 m by 3 m, the maximum height would be 6 m for use outside and 7 m for inside.

Always check the safe height to base ratio in the instruction manual.

Remember, the stability of any tower will be affected if it is:

sheeted and/or likely to be exposed to strong winds; loaded with heavy equipment or materials; used to hoist heavy materials or support rubbish chutes; used for operations involving heavy or awkward equipment,

e.g. grit blasting, water-jetting, etc; climbed from the outside; used as a support for ladders.

In these cases, extra support or alternative height to base ratios may be needed.

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Before using the tower always check that the:

scaffold is vertical; wheel brakes are on.

1.24.5 Tower Scaffolds Continued

Access.

There must be a safe way to get to and from the work platform. It is not safe to climb up the end frames of the tower except where:

the frame has an appropriately designed built-in ladder; a purpose-made ladder can be attached safely on the inside.

Check with the manufacturer or supplier before fitting a ladder to the outside. Always make sure there is a secure handhold at all landing places.

Edge protection.

Provide suitable edge protection on platforms where a person could fall. Guard rails should be at least 910 mm high and toe boards at least 150 mm high. An intermediate guard rail or suitable alternative should be provided so the unprotected gap does not exceed 470 mm.

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Brick-guards or other barriers may be used instead of the intermediate guard rail as long as they are strong enough and placed so no one can fall through them.

Moving the tower.

When moving a tower:

check that there are no power lines or other overhead obstructions; check that the ground is firm and level; push or pull only from the base - never use powered vehicles; never move it while there are people or materials on the upper

platforms; never move it in windy conditions.

Protecting the public.

When towers are used in public places, extra precautions may be needed:

Minimise the storage of materials and equipment on the working platform.

Erect barriers at ground level to prevent people from walking into the tower or work area.

Remove or board over access ladders to prevent unauthorised access if it is to remain in position unattended.

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Before you use a tower in a public place, check whether you need a licence from the local authority.

Scaffold inspection.Tower scaffolds must be inspected by a competent person:

before first use; after substantial alteration; after any event likely to have affected its stability.

If the tower remains erected in the same place for more than seven days, it should also be inspected at regular intervals (not exceeding seven days) and a written report made. Any faults found should be put right.

Tower scaffolds can be erected quickly and - used properly - can give good safe access. However, they have been involved in numerous accidents because they have not been erected or used correctly - manufacturer's instructions must always be followed.

If the scaffold is owned by the company using it, a copy of the instruction manual must be available. If the scaffold has been hired, the hirer must provide this information.

For all types of tower scaffold, the requirements are to ensure that:

The tower is vertical. 15

The legs are resting properly on firm, level ground and all wheels and outriggers are locked.

There is a safe means of access, for example, an internal ladder. Edge protection is provided for all platforms more than 2 metres

above the ground.

In situations where the tower will be subject to extra stresses (for example if the tower is protected by weather-proof sheeting, used for grit blasting or lifting heavy loads) it will be necessary to provide additional support which might include tying to the structure being served.

Edge protection be provided at a height of?

1.   ?   2.5 meters2.   ?   2 meters3.   ?   1.5 meters

4.   ?   3 meters

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1.24.6 Mobile and Suspended Access Equipment

There will be many occasions when it will not be possible to work from an existing structure and the use of a scaffold-based working platform would not be appropriate. A range of mobile access equipment can be used, including:

mobile elevated working platforms (MEWPs); mast platforms which are, in essence transportable lifts which are

bought to the required place of work.

(cradles, bosun's chairs or seats, rope access equipment at which we will look later)

It is essential that personnel who are going to use such equipment should be well-trained and competent to operate it. They should also learn emergency and evacuation procedures so that they know what to do, for example, if the power supply to the platform fails or fire breaks out in the building where the work is taking place.

This information should be given on a hand-over certificate which will be provided by the supplier/installer. The certificate must also provide all the relevant information about safe working loads and so on.

The safe system of work must ensure that: 17

the area where the work is to be carried out is barriered off or made secure to prevent unauthorised entry;

people cannot be struck by any moving parts as the platforms rise or descend;

the platform is protected from damage, in particular by being struck by passing vehicles;

the access equipment is secure and capable of withstanding high winds if it needs to be used outside.

It is worth saying a few specific words about MEWPs.

Mobile elevated work platforms (MEWP)

MEWP’s can provide excellent safe access to high level work. Anyone responsible for use of a MEWP must ensure that:

the operator is fully trained; the MEWP is provided with guard rails, toe-boards and other suitable

barriers; the MEWP is used on firm and level ground with tyres properly

inflated; any outriggers are extended and chocked as necessary before the

platform is raised; everyone concerned knows what to do in the event of a failure of the

platform in the raised position.

Users of MEWPs must never operate the MEWP near overhead cables or other dangerous machinery or move the equipment with the platform in the raised position

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1.24.7 Temporarily Suspended Access Cradles and Platforms

Most accidents involving temporarily suspended access cradles and

platforms happen because of:

unsafe access to and from the cradle; insufficient or poorly secured counterweights or other systems for

holding the cradle or platform in place; failure of the cradle platform or components, probably because

manufacturer's instructions on erection and dismantling have not been followed.

Anyone using a cradle must check that:

it has adequate guard-rails and toe-boards and material cannot fall off;

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it can be fitted close to the building which must be capable of carrying the loads placed upon it;

a secondary safety rope fitted with a fall arrest device is provided and used;

adequate operating instructions and technical support are available; there is safe access into, and safe egress from, the cradle

1.24.8 Boatswain’s ( ‘Bosun’s’) Chairs and Rope Access

Techniques.

In situations where it is not practicable to provide a solid working platform, boatswain's chairs can be used for light, short-term work. In general, the chair comprises a seat supported on a shock-absorbing line (lanyard) via a central suspension point and a carrying point for tools.

Rope-access techniques, sometimes known as abseiling, are generally used for inspections rather than actual construction work. Again, they should only be used where access from a working platform is not practicable.

It goes without saying that the erection, maintenance and use of any chair and rope techniques requires training and competence.

Safety harnesses.

For work at heights, providing a safe place of work and system of work to prevent falls should always be the first consideration. However, there may be circumstances in which it is not practicable for all or any of the requirements for guard rails etc to

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be met, for example where guard rails have to be taken down for a short period of time to (un)load materials.

Where people may still approach an open edge from which they would be liable to fall, other forms of protection will be needed and in such cases a suitably-attached harness and line could allow safe working.

It is important to remember that a harness will not prevent a fall, it can only minimise the risk of injury; the person who falls may be still be injured when the line goes tight and/or by striking parts of the structure during the fall.

1.24.9 Ladders

Ladders are a means of getting to a workplace. They may be used as a workplace in their own right for light short-term work only.

If it is not possible to provide a better means of access and ladders have to be used, it is necessary to make sure that:

the ladder(s) are in good condition; the ladder(s) can be fixed to prevent running sideways or slipping

away from the wall; the bottom of the ladder is supported on a firm level surface, if

possible making use of ladder feet; if the bottom of the ladder cannot be fixed then a second person

should foot the ladder, both to hold it firmly and as a look-out to stop people walking into it;

the ladder should extend a sufficient height above the landing place to ensure that workers can safely and comfortably transfer from and to the ladder.

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All light tools should be carried in a shoulder bag or holster attached to a belt leaving both hands free; heavy or bulky loads must not be allowed.

As a rule of thumb, the ladder needs to be one out for every four up. Particular care is needed with step-ladders which are so prone to overturn when subjected to any kind of side loading, caused for example by over-reaching.

1.25 Protection Against Falling Materials

Firstly, good housekeeping is vital, keeping platforms clear of all

loose materials. The next line of defence comprises toe-boards, solid barriers, brick guards or similar arrangements at open edges.

In public places, arrangements such as nets and covered walkways may be needed to give the necessary protection. Plastic sheeting may be required to keep down dust levels and control water sprays.

Roof work.

Almost one in five of the workers killed in construction accidents was involved in roof work at the time of their deaths - fatal accidents happen to both specialist roofers and general construction workers. Most of the deaths are a result of falls from and falls through.

Sheeted roofs must never be trusted. From whatever material they are made - asbestos cement, fibreglass, steel or plastic - they will become fragile with age; in addition, apparently sound sheeting might not be properly supported.

Roof openings and roof lights are an extra hazard. They may be difficult to identify in certain light conditions, particularly if they have been covered with bituminous paint. The key to work on fragile roofs is to spread the load by the use of

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purpose-made roof-boards and to post warning notices at suitable places on the approaches to the roof (figure 11).

Guard rails and toe-boards or suitable edge barriers may need to be erected if there is any risk of workers falling from the roof. Whenever roof work is going to be undertaken, the worker(s) must be able to:

reach the roof, safely; move across the roof, safely; Work on the roof, safely.

WARNING

1.25.1 Inspections & Reports

Introduction.

This section sets out the specific requirements for the inspection of

working platforms; personal suspension equipment; excavations; cofferdams and caissons; the reports which have to be made following certain inspections.

Those in control of workplaces should ensure inspections are carried out by a competent person.

All employers and people in control of construction work should make sure that places of work are safe before they allow their workers to use them for the first time.

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Stop work if the inspection shows it is not safe to continue.

1.25.2 ReportsThe competent person must:

complete the inspection report before the end of the working period; provide the report or a copy to the person for whom the inspection

was carried out within 24 hours.

Reports must be kept on site until the work is complete. Reports should then be kept for three months at an office of the person for whom the inspections were carried out.

A report is not needed following every inspection. A report is only needed for a tower scaffold if it stays in the same

place for seven days or more.

Where an inspection of a working platform or any personal suspension equipment is carried out

before being used for the first time; after any substantial addition, dismantling or other alteration;

only one report is needed for any 24-hour period.

Where an inspection of an excavation is carried out, only one written report is needed in any seven day period unless something happens to affect its strength or stability.

The record must include the following information:

Name and address of person on whose behalf the inspection was carried out.

Location of the workplace inspected.

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Description of workplace or part of workplace inspected (including any plant and equipment and materials, if any.

Date and time of inspection. Details of any matter identified that could lead to a risk to the health

and safety of anyone. Details of any action taken as a result of any matter identified in the

last point. Details of any more action considered necessary. The name and position of the person making the report.

Note: Personal suspension equipment is used to provide a place from which to work and includes boatswain's chairs and abseiling equipment. It does not include harnesses and lines which are used solely to limit a fall if one happens.

1.25.3 Inspection Report

We have included an example of an inspection

report as required by the Construction (Health,

Safety and Welfare) Regulations

INSPECTION REPORT

Report of results of every inspection should include as a minimum:

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1. Site address.2. Date and time of inspection. 3. Location and description of workplace (including any

plant, equipment or materials) inspected. 4. Matters which give rise to any health and safety risks. 5. Can work be carried out safely? 6. If not, name of person informed. 7. Details of any other action taken as a result of matters

identified in 5 above. 8. Details of any further action considered necessary. 9. Name and position of person making the report. 10. Date report handed over.

INSPECTION REPORTS: NOTES

Place of work requiring inspection

Timing and frequency of inspection.

Before being used for the first time.

After substantial addition, dismantling or alteration.

After any event likely to have affected its strength or stability.

At regular intervals not exceeding seven days.

Before work at the start of every shift.

 After accidental fall of rock, earth or any material.

 Any working platform or part thereof or any personal suspension equipment.

✓ ✓ ✓ ✓

 Excavations which are supported

✓ ✓ ✓

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in pursuit of paragraphs (1), (2) or (3) of regulation 12.  Cofferdams and caissons.

✓ ✓

NOTES: General. The inspection report should be completed before the end of the

relevant working period.

The person who prepares the report should, within 24 hours, provide either the report or a copy to the person on whose behalf the inspection was carried out.

The report should be kept on site until work is complete. It should then be retained for three months at an office of the person for whom the inspection was carried out.

1.25.4 Working Platforms Only

Working platforms only.

Any inspection is only required where a person is liable to fall from a place of work. Any employer or any other person who controls the activities of people using a scaffold shall ensure that it is stable and of sound construction and that the relevant safeguards are in place before their employees or people under their control first use the scaffold.

No report is required following the inspection of any mobile tower scaffold which remains in the same place for less than seven days. Where an inspection of a working platform or part thereof or any personal suspension equipment is carried out:

before it is taken into use for the first time; or after any substantial addition, dismantling or other alteration;

not more than one report is required for any 24 hour period.

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1.25.5 Excavations OnlyThe duties to inspect and prepare a report apply only to any excavation which needs to be supported to prevent any person being trapped or buried by an accidental collapse, fall or dislodgement of material from its sides, roof or area adjacent to it.

Although an excavation must be inspected at the start of every shift, only one report of such inspections is required every seven days.

Reports must be completed for all inspections carried out during this period for other purposes, e.g. after accidental fall of material.

1.25.6 Checklist of Scaffolding Faults

Checklist of typical scaffolding faults.

Footings Standards Ledgers BracingPutlogs and transoms

Couplings Bridles Ties Boarding Guard rails and toe boards

Ladders

Soft

and uneven Not plumb Not level

Some missing

Wrongly spaced

Wrong fitting

Wrong spacing

Some missing

Bad boards Wrong height

Damaged

No

base plates Jointed at same height

Joints in same bay

Loose Loose Loose Wrong couplings

Loose Trap boards

Loose Insufficient length

No

sole plates Wrong spacing

Loose Wrong fittings

Wrongly supported

Damaged No check couplers

Not enough

Incomplete Some missing

Not tied

Undermined Damaged Damaged No check Insufficient

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couplers supports

1.26 Safety in Excavations

Introduction.

Every year, people are killed or seriously injured when working in excavations. Excavation work has to be properly planned, managed, supervised and carried out to prevent accidents. This unit provides advice for those involved in excavation work.

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Planning.

Before digging any excavations, it is important to plan against the following:

Collapse of the sides. Materials falling onto people working in the excavation. People and vehicles falling into the excavation. People being struck by plant. Undermining nearby structures. Contact with underground services. Access to the excavation. Fumes. Accidents to members of the public.

Make sure the necessary equipment needed such as trench sheets, props, baulks, etc, is available on site before work starts.

1.26.1 Excavation Collapse

A range of proprietary trench boxes and hydraulic wallings allow trench supports to be put in place without requiring people to enter the excavation.

Prevent the sides and the ends from

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collapsing by battering them to a safe angle or supporting them with timber, sheeting or proprietary support systems.

Do not go into unsupported excavations. Never work ahead of the support. Remember that even work in shallow trenches can be dangerous. You

may need to provide support if the work involves bending or kneeling in the trench.

Materials falling into excavations.

Do not store spoil or other materials close to the sides of excavations. The spoil may fall into the excavation and the extra loading will make the sides more prone to collapse.

Make sure the edges of the excavation are protected against falling materials. Provide toe boards where necessary.

Wear a hard hat when working in excavations.

People and vehicles falling into excavations.

Where there is a risk of injury, take steps to prevent people falling into excavations. i.e. provide substantial barriers, e.g. guard rails and toe-boards.

Keep vehicles away from excavations wherever possible. Use brightly-painted baulks or barriers where necessary.

Where vehicles have to tip materials into excavations, use stop-blocks to prevent them from over-running. Remember that the sides of the excavation may need extra support.

1.26.2 Excavations - Safe Practices

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People Being Struck by Plant

.

Keep workers separate from moving plant such as excavators. Where this is not possible, use safe systems of work to prevent people being struck.

Plant operators should be competent.

Undermining nearby structures.

Make sure excavations do not affect the footings of scaffolds or the foundations of nearby structures. Walls may have very shallow foundations which can be undermined by even small trenches.

Decide if the structure needs temporary support before digging starts. Surveys of the foundations and the advice of a structural engineer may be needed.

Avoiding underground services.

Look around for obvious signs of underground services, e.g. valve-covers or patching of the road surface.

Use locators to trace any services. Mark the ground accordingly. Make sure that the person supervising excavation work has service

plans and knows how to use them. Everyone carrying out the work should know about safe digging practices and emergency procedures.

Access.

Provide good ladder access or other safe ways of getting in and out of the excavation.

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Fumes.

Exhaust fumes can be dangerous. Do not site petrol or diesel-engined equipment such as generators or compressors in, or near the edge of, an excavation unless fumes can be ducted away or the area can be ventilated.

1.26.3 Excavations - Safe Practices

Protecting the Public.

Fence off all excavations in public places to prevent pedestrians and vehicles falling into them.

Where children might get onto a site out of hours, take precautions (e.g. backfilling or securely covering excavations) to reduce the chance of them being injured.

Supervision.

A competent person must supervise the installation, alteration or removal of excavation support.

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People working in excavations should be given clear instructions on how to work safely.

Inspecting excavations.

A competent person must inspect excavations:

at the start of each shift before work begins; after any event likely to have affected the strength or stability of the

excavation; and after any accidental fall of rock, earth or other material.

A written report should be made after most inspections. Stop work if the inspection shows the excavation to be unsafe.

Underground work accidents generally involve one or more of the following:

Trench collapse because of inadequate side support. Undermining of nearby structures. Falls into the excavation of people, materials or vehicles. Contact with buried underground services. Toxic gases from natural decay of vegetation etc or toxic

exhaust fumes from petrol or diesel equipment.

Groundwork has to be properly planned and carried out to prevent accidents. Soil tests or trial holes may be required to determine the conditions likely to be found on the site, particularly of course for larger excavations.

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The collapse of excavations can be prevented in two ways:

Battering, i.e. having angled sides to the excavations (very shallow in the case of powdery soils or where wet conditions may make the soil mobile), or if this is not possible, supporting the (vertical) sides of the excavation.

For the latter, many types of system are available - timbering and props, pre-fabricated boxes which are lowered into the excavation, trench sheeting systems etc.

Above all, groundwork needs to be planned, undertaken and maintained by people with suitable expertise. The CDM Regulations, to which we will soon briefly return, provide a framework for the management of the work.

As far as the undermining of nearby structures is concerned, it should be remembered that many walls, particularly boundary walls, have very shallow foundations indeed.

Excavations must be guarded appropriately. Remember that ground level working can become working at height in the proximity of an excavation.

All excavations in public places should be suitably fenced off to prevent members of the public approaching them. Vehicles must be kept away from the excavation unless they have to approach for the purposes of material delivery and removal; in such situations, they must use approved routes which will bear their weight, stop blocks will be required to prevent over-running into the excavation.

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Similarly, areas close to the sides of excavations must never be used for storing spoil and other materials or for parking plant and vehicles.

Underground services - gas, water and electricity - can be easily damaged during excavation work leading to electrocution, fire, flooding and - it is important not to forget this - interruption of services to hospitals, offices and so on. Ideally, excavations should be kept away from existing underground services; these can be identified by a combination of:

Clues provided by manhole covers, street lights etc Cable and other service plans of the area. Detection devices (conventional detectors will miss plastic

pipes).

In practice, excavations may have to be made in areas where there are known to be existing and/or disused services. Safe practices must be employed once the digging actually starts:

Watch carefully for evidence of previously unknown pipes or cables - check using the detection device.

Dig trial holes by hand to confirm the position of pipes and cables - this is particularly important where plastic pipes are used.

Dig by hand near buried pipes or cables, using spades and shovels rather than picks and forks.

Treat all pipes and cables as live unless known otherwise. Report any suspected damage to services. Ensure there is an emergency plan to deal with damage to

cables or pipes. Update service plans for the benefit of those in the future.

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Turning to the chemical hazards that may be encountered in excavation work, fumes or exhaust gases from equipment can collect and accumulate in excavations and pose serious hazards.

In deep excavations, particularly in areas such as river-beds and estuaries, it may be necessary to use gas detection equipment to ensure that toxic or explosive levels of decomposition gases are not building up.

At the start of each shift or after any event that may have affected their strength or stability, the excavations and supporting system should be inspected.

It is necessary for you to make a list of the hazards of both excavations and working heights, Compare the lists: what comments can you make?

1.27 Welfare Facilities at Fixed Construction Sites

Introduction.

Construction site workers need adequate toilet and washing facilities, a place to warm up and eat their food and somewhere to store clothing. However, these basic

requirements are often neglected. Good facilities can have a positive benefit on health and well-being and can help prevent dermatitis.

This section is aimed at employers and the self-employed in construction and those in control of construction sites. It describes the

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minimum welfare facilities which should be provided or made available on fixed construction sites.

Duties. If you have overall control of the site, you are responsible for making

sure that legal requirements for welfare are met for the site. In practice, this means the principal contractor or other person in control of the site will often either provide or arrange for common facilities for everyone.

If you are an employer or are self-employed, you need to ensure that everyone working under your control is either provided with or has access to suitable welfare facilities. This will need to be agreed with the person who has overall control of the site.

If work is carried out in occupied premises, e.g. offices, factories, etc, it may be possible to make arrangements with the client to use the permanent facilities at the premises.

1.27.1 Planning

Make sure welfare arrangements are clearly addressed in the health and safety plan.

Consider welfare facilities, their location on site and regular maintenance during the planning and preparation stage of any project.

Arrange for equipment to be available, provided, sited and connected to services before construction work (including demolition) starts or when additional numbers of workers start on site.

Make sure the facilities reflect the site size, nature of the work and numbers of people who will use them. If a large number of people are working on site or the work being carried out is particularly dirty or involves a health risk (e.g. pouring concrete), you will need more washing facilities (which may include showers), toilets, etc.

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1.27.2 General Welfare Requirements

General welfare requirements.

Ensure that all toilet, washing, changing, personal storage and rest areas are accessible and have adequate heating, lighting and ventilation.

Facilities may need to be provided at more than one location to make sure workers have easy access.

Make sure someone is responsible for keeping the facilities clean and tidy. How often the facilities will need cleaning will depend on the number of people on site and on how quickly they become dirty. Basic daily cleaning may not always be enough.

Toilets.

Make sure that an adequate number of toilets are provided at all times. Men and women may use the same toilet, provided it is in a lockable

room and partitioned from any urinals which may also have been provided. Otherwise, separate toilets will be needed.

Wherever possible, connect toilets to a mains drainage system and ensure they are water flushing. If you cannot do this, use facilities with built-in supply and drainage tanks.

Units used by female workers should have effective means for disposal of sanitary waste.

Make sure adequate supplies of toilet paper are always available.

1.27.3 Washing Facilities

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Put washing facilities next to both toilets and changing areas and make sure they include:

basin(s) or sink(s) large enough for people to wash their face, hands and forearms;

a supply of hot and cold or warm running water; soap and towels (either cloth or paper) or dryers.

If mains water is not available, use clean water supplied from a tank.

You may need more washing facilities, including showers, where the work is particularly dirty or when workers are exposed to especially hazardous substances, e.g. development of contaminated land, or demolition of old industrial buildings which are contaminated with toxic substances, etc. These will need to be separate from the main facilities.

You may need specialist facilities for certain activities, e.g. working with lead, asbestos, tunnelling in compressed air, etc.

Men and women can share basins used for washing hands, face and arms.

A shower may be used by both men and women so long as it is in a separate, lockable room which can be used by one person at a time.

1.27.4 Storing and Changing Clothing

Every site should have arrangements for storing clothing not worn on site (e.g. jackets, training shoes etc) and protective clothing needed for site work (e.g. Wellington boots, overalls, reflective jackets).

Separate lockers might be needed, although on smaller sites the site office may be a suitable storage area, provided it is kept secure.

Where there is a risk of protective site clothing contaminating everyday clothing, store items separately.

Men and women should be able to change separately. Make sure that wet site clothing can be dried. Many fires have been caused by placing too much clothing to dry on

electrical heaters, making the heater overheat. If electrical heaters are

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used, ensure they are properly ventilated and if possible, fitted with a high temperature cut-out device.

1.27.5 Rest FacilitiesProvide facilities for taking breaks and meal breaks. The facilities

should provide a shelter from the wind and rain and be heated as necessary.

The rest facilities should have tables and chairs, a kettle or urn for boiling water and a means for warming up food (for example, a gas or electrical heating ring, or microwave oven).

Non-smokers should be able to use the facilities without suffering discomfort from tobacco smoke. In many countries, these areas are all now non-smoking. However, in some countries this ban does not apply; in cases where smoking is permitted in rest facilities, provide ventilation, or if this is not possible, you may need to provide separate areas for smokers and non-smokers, or ban smoking in the presence of non-smokers.

On small sites, the site office or hut can make a suitable rest area, especially if it is one of the common portable units. Do not store plant, equipment or materials in rest areas.

1.27.6 Drinking Water

Make sure there is a supply of wholesome drinking water readily available. Where possible, it should be supplied direct from the mains.

If water is stored, protect it from possible contamination and make sure it is changed often enough to prevent it from becoming stale or contaminated.

Clearly mark the drinking water supply to prevent it being confused with water which is not fit to drink or hazardous liquids.

Provide cups or other drinking vessels at the water tap, unless the water is supplied in an upward jet which can be drunk easily (for example, a drinking fountain).

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1.27.7 Heating

Inadequately-ventilated LPG cookers and heaters can produce carbon monoxide. Gas may escape from leaking cylinders which have not been properly turned off. You can eliminate these risks by using properly maintained electrical equipment instead.

If this is not possible, reduce the risk by:

using and storing the cylinders in safe, well-ventilated places outside the accommodation (including overnight);

providing adequate combustion ventilation (provide fixed grills at high and low level);

checking that cylinders are properly turned off when not in use; turn off the tap at the appliance and isolate the cylinder.

Having set the scene of welfare facilities required on construction sites, we will now consider the many health hazards to which construction workers are exposed.

1.28 Asbestos

Asbestos Regulations

Asbestos is the UK's biggest workplace killer. An estimated 5,000 people die each year from the asbestos cancer mesothelioma and asbestos-related lung cancers - 13 people every day of the year. Asbestos has also been linked to other cancers, including throat and stomach cancer.

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HSE says 25 per cent of UK asbestos-related deaths each year are in the building and maintenance trades and these figures are rising.

Although asbestos is now banned in many countries, the three main types of asbestos - blue, brown and white asbestos - can still be found in the workplace. There is no safe level of exposure and all types are dangerous.

Asbestos is still used in some countries and as such, any tasks involving work with or near to asbestos should be performed in accordance with the relevant provisions of the ILO code of practice on Safety in the use of asbestos, in particular the provisions of Chapter 18 on construction, demolition and alteration work.

The danger from asbestos comes from drilling, cutting, sanding or disturbing materials made from asbestos and breathing in the dust. There is usually a long delay between first exposure to asbestos and the onset of disease. This can vary from a few to 60 years. Mesothelioma is a particularly aggressive cancer; once the cancer has developed, it is unusual for the sufferer to survive for more than two years. Around 75 per cent die within a year.

Asbestos inhalation causes a number of diseases. These are asbestosis (the scarring of lung tissue), lung cancer, mesothelioma and pleural disease. Pleural disease includes calcification of the lungs and pleural effusion (fluid on the lungs).

There are up to six million tons of asbestos in schools, hospitals, ships, offices and factories in the UK alone. Asbestos is commonly found:

in insulation and lagging on pipe work, boilers and duct work; as a sprayed coating on steelwork, concrete walls and ceilings;

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in insulation boarding or loose packing in wall partitions, fire doors and ceiling voids;

asbestolux and marinite boarding; in cement products such as corrugated roof sheeting, wall sheeting,

roof tile, guttering and downpipes, decorative finishes to walls and ceilings (pre-1982 'artex' finishes), cold water tanks and surrounding insulation jackets.

It is also found in some older heaters, ironing boards and asbestos rope seal on some old oven doors.

If you find, or believe you have found asbestos, stop work and get it checked out. If you have been exposed to asbestos make sure your GP adds this in your medical notes. These should also say that should you develop lung cancer in later life you will want a post mortem conducted. This isn't morbid, it will help ensure your family receives deserved compensation.

1.28.1 AsbestosIt is important to protect building and maintenance workers, the

largest group who are today at risk of exposure to asbestos, and help prevent thousands of asbestos-related deaths.

Duty holders should:

find out if asbestos is present; make and keep a record of the location and condition of these

materials ; monitor the asbestos;

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ensure safe maintenance and - if necessary - removal; inform those likely to disturb it in the course of their work of its

presence; tell the emergency services about it; and keep the situation under review.

Additionally:

Presume materials to contain asbestos unless there is strong evidence they do not.

Prepare a plan of how any asbestos risk is to be managed.

A 'Duty holder' is 'anyone responsible for maintaining and repairing all or part of a property, or who has control of the building.'

Most work on asbestos insulation, asbestos insulating-board and lagging, including sealing and removal, should normally be done by a licensed operator.

The national asbestos register of UK buildings aims to prevent any further deaths from unnecessary exposure of workers to asbestos by eventually listing every property in the UK that contains asbestos. The project is supported by the Trade Union Congrees, the HSE and the Government.

1.28.2 Asbestos.Further measures are designed to protect maintenance workers and

others from asbestos fibres. This will make it easier for employers to comply with their duties towards workers as the location of asbestos will be known in every non-domestic building so there can be no excuses for a failure to protect their workers.

Anyone who has maintenance and repair responsibilities for non-domestic premises will have a duty under the legislation to

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find out if there is asbestos in the premises, its amount and what condition it is in;

presume materials contain asbestos unless they have strong evidence that it is not;

make and keep up to date a record of the location and condition of the asbestos containing materials or presumed asbestos containing materials in their premises;

assess the risk from the material; prepare a plan that details how they are going to manage the risk from

that material; take the steps necessary to put the plan into action; review and monitor the plan and the arrangements made to put it into

place; and provide information on the location and condition of the material to

anyone who is liable to work on it or disturb it.

These provisions will make it much easier for employers of maintenance workers to carry out the checks they need to protect their workers. Any work involving maintenance, repair or demolition is now considered high risk.

For many jobs, building owners will already know where asbestos can be found in their buildings. In some cases they may even have labelled it to warn others who may come into contact with it. However, often the presence of asbestos will not be obvious. It is sensible to assume that any building constructed or refurbished before the 1980s will contain asbestos-based materials.

No work should be carried out which is likely to expose employees to asbestos unless an adequate assessment of exposure has been made. This means that the building or area of the building where work is to be done should be checked to identify the location, type and condition of any asbestos which could be disturbed during the work.

1.28.3 Asbestos

Some of the most common materials containing asbestos are:

Boiler and pipework coatings and laggings.

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Sprayed coatings providing fire or acoustic insulation. Insulation board. Cement-based boards, sheets and formed products. Ceiling (and some floor) tiles. Gaskets and paper products used for thermal and electrical insulation. Some textured surface coatings.

In general, the softer the material the more easily it is damaged and the more likely it is to release fibres when disturbed or worked on. The greater the fibre release, the greater the risk to health it will generate and the higher the standard of precautions required when working with that material.

Many of the softer materials, for example, boiler lagging, will be protected by a hard outer coating. If the protective outer coating could be inadvertently damaged during the work, take precautions either to protect it or to ensure that if it is damaged, the subsequent release of asbestos will not create a risk. Work in which asbestos insulation, asbestos coating or asbestos insulating board is removed, repaired or disturbed will normally have to be carried out by a specialist contractor.

If asbestos, or what is suspected to be asbestos, which was not identified during the initial assessment is discovered, stop work. Protect it from further damage until it has been decided how work can proceed in safety. If there is doubt about the presence of asbestos, seek the advice of a specialist analyst.

There is a duty on an employer to prevent the exposure of employees to asbestos, or to reduce exposure to the lowest reasonably practicable level. So, if possible, a work method which avoids any disturbance of asbestos-containing materials should be chosen. If this is not possible, before carrying out any work which is liable to expose employees, or others, to asbestos, make an assessment of the likely exposure.

It is important to make this assessment even when exposure to asbestos is infrequent and only happens by chance, e.g. during building refurbishment or repair work

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such as gas fitting, plumbing or electrical work. The assessment will help in deciding what precautions need to be taken to protect people who may be affected by the work.

1.28.4 AsbestosEssential points to remember when working with small

quantities of hard asbestos-containing materials:

Asbestos cement sheet or asbestos cement products like ducts and pipework are considered less hazardous varieties but an assessment of exposure is still required.

Avoid exposure to airborne dust and provide necessary protective equipment, including respirators. Only use respirators to control exposure after all other steps to reduce exposure have been taken.

1.28.5 Working with Asbestos Cement.

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Where exposure is to low levels of fibre, for example, when removing small numbers of good condition ceiling tiles or drilling a few holes as part of plumbing or electrical work, disposable respirators may give adequate protection.

For more extensive work involving breaking boarding or handling damaged materials, more precautions such as full-face respirators, disposable overalls and ventilated enclosures as required when working with lagging may be necessary.

Don't break asbestos board or sheeting; try to remove it as an undamaged piece. Where sheet has to be worked on, wet it first if possible. Handle the material carefully - don't drop materials onto the floor or ground. Pick up loose pieces immediately. If working outdoors, for example, taking down roof sheets, make sure vehicles don't run over sheets at ground level - this results in high dust levels.

Use hand tools - drilling and cutting sheet with power tools produces a lot of dust. Use the working methods and precautions described in the UK HSE's asbestos ACoP, or other equally safe methods. Avoid blasting, sanding and grinding the material.

If asbestos materials are removed, they must be disposed of safely. Board and sheet materials should usually be wrapped and sealed in polythene sheet and marked to indicate the presence of asbestos. Only specified tips accept asbestos-containing waste; check with the local waste disposal authority for details.

Buildings should be assumed to contain asbestos which where

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1.

1.   ?   Built prior to the 1980s

2.   ?   Built in the 1990s

What is the employers 1st objective with regard to exposure of Asbestos?

1.

1.   ?   Prevent Exposure.2.   ?   Minimise Exposure.

3.   ?   Supply Protective Clothing.

1.29 VibrationMany jobs in construction involve the use of hand-held power tools

such as pneumatic breakers and disc grinders. The vibration from such equipment can affect the fingers, hands and arms and, in the long term, do permanent damage. Parts of the fingers go white and numb and there is a loss of touch sensation.

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If anyone uses hand-held power tools, they should identify, assess and prevent or control the risk from vibration.

The manufacturer or suppliers information should indicate if there is a vibration problem.

Where possible, choose low-vibration tools. This reduces exposure to vibration, noise and dust; it may also be quicker and cheaper.

Assessment.

The information from the manufacturer or supplier, the amount of time the tools are used and discussions with the people using the tools should reveal the tools most likely to present a risk. Make sure workers using vibrating tools know about the risks and what they need to do to minimise them.

Prevention.

Can the job be done in another way which does not involve using hand-held power tools (for example, by using a hydraulic breaker to break a concrete beam?

Control.

Maintain equipment so that it is properly balanced, has no loose or worn out parts and blades/cutters are sharp etc. Use the power tool and attachment which will do the job properly in the shortest time. To protect against

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vibration, workers should keep their hands warm to get a good flow of blood into the fingers by:

wearing gloves; having hot food or drinks; massaging the fingers.

1.30 Cement

Introduction.

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Cement is widely used in construction. Anyone who uses cement (or anything containing cement, such as mortar, plaster and concrete) or is responsible for managing its use should be aware that it presents a hazard to health.

Health effects.

Cement can cause ill-health mainly by:

skin contact; inhalation of dust; and manual handling.

Skin contact.

Contact with wet cement can cause both dermatitis and burns.

Dermatitis.

Skin affected by dermatitis feels itchy and sore, and looks red, scaly and cracked. Cement is capable of causing dermatitis by two mechanisms - irritancy and allergy.

Irritant dermatitis is caused by the physical properties of cement that irritate the skin mechanically. The fine particles of cement, often mixed with sand or other aggregates to make mortar or concrete, can abrade the skin and cause irritation resulting in dermatitis. With treatment, irritant dermatitis will usually clear up. If exposure continues over a longer period, the condition will get worse and the individual is then more susceptible to allergic dermatitis.

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Allergic dermatitis is caused by sensitisation to the chromium (chromate) present in cement. The way this works is quite distinct from that of irritancy. Sensitisers penetrate the barrier layer of the skin and cause an allergic reaction. Chromium is known to be the most common cause of allergic dermatitis in men. Research has shown that between 5% and 10% of construction workers may be sensitised to cement and that plasterers, concreters and bricklayers are particularly at risk. Once someone has become sensitised to chromium, any future exposure may trigger dermatitis. Some skilled tradesmen have been forced to change their trade because of this. The longer the duration of skin contact with a sensitiser, the more it will penetrate the skin and the greater the risk of sensitisation will become. Therefore, if cement is left on the skin throughout the working day, rather than being washed off at intervals, the risk of contact sensitisation to chromium will be increased. Both irritant and allergic dermatitis can affect a person at the same time.

1.30.1 Cement Burns

Wet cement can cause burns. The principal cause is thought to be the alkalinity of the wet cement.

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If wet cement becomes trapped against the skin, for example by kneeling in it or if cement falls into a boot or glove, a serious burn or ulcer can rapidly develop.

These often take months to heal and in extreme cases will need skin grafts or can even lead to amputation.

Serious chemical burns to the eyes can also be caused following a splash of cement.

1.30.2 Inhalation of Cement Dust

High levels of dust can be produced when cement is handled, for example when emptying or disposing of bags.

In the short term, exposure to high levels of cement dust irritates the nose and throat.

Concrete cutting drilling or grinding can also produce high levels of dust which may contain silica.

1.30.3 Manual Handling

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Working with cement also poses risks such as sprains and strains, particularly to the back, arms and shoulders from lifting and carrying cement bags, mixing mortar etc.

More serious damage to the back can be caused in the long term if workers are continually lifting heavy weights.

1.30.4 Ill-health Prevention and Health Surveillance

Skin contact.

You should first consider using elimination or substitution to prevent the possibility of contact with cement. Otherwise, you should apply control measures which minimise contact with the skin either directly or indirectly from contaminated surfaces in the working environment.

An important way of controlling cement dermatitis is by washing the skin with warm water and soap, or other skin cleanser, and drying the skin afterwards. Sinks should be large enough to wash the forearms and have both hot and cold (or warm) running water. Soap and towels should be provided. Facilities for drying clothes and changing clothes should also be available.

Gloves may help to protect skin from cement, but they may not be suitable for all aspects of construction site work. Caution is advised when using gloves as cement trapped against the skin inside the glove can cause a cement burn. You should provide protective clothing, including overalls with long sleeves and long trousers.

Employers should arrange for employees to receive suitable health surveillance where there is exposure to a substance known to be associated with skin disease and where there is a reasonable likelihood that the disease

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may occur. This means you should provide health surveillance for workers who will be working with wet cement on a regular basis.

Health surveillance is needed to:

protect individuals; identify as early as possible any indicators of skin changes related to

exposure, so that steps can be taken to treat their condition and to advise them about the future; and

give early warning of lapses in control.

Health surveillance must never be regarded as reducing the need to control exposure or to wash cement off the skin.

Simple health surveillance will usually be sufficient. Skin inspections should be done at regular intervals by a competent person, and the results recorded. Employers will probably need the help of an occupational health nurse or doctor to devise a suitable health surveillance regime and they will need to train a responsible person, for instance a supervisor, to carry out the skin inspections.

A responsible person is someone appointed by the employer who, following instruction from an occupational health physician or nurse, is competent to recognise the signs and symptoms of cement-related dermatitis. The responsible person should report any findings to the employer, and will need to refer cases to a suitably qualified person (e.g. an occupational health nurse).

The employer must keep health records containing the particulars set out in the Appendix to the General COSHH Approved Code of Practice.

Employers are also required to provide employees with information, instruction and training on the nature of the risk to health, and the precautions to be taken. This should include characteristic signs and symptoms of dermatitis.

Employees should be encouraged to examine their own skin for any such signs and report them. Reports should be made to the responsible person or to the occupational health nurse.

Cement can cause ill health mainly by:

1.

1.   ?   inhalation of dust57

2.   ?   All of these

3.   ?   skin contact

1.31 Solvents

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Introduction

Solvents are chemical substances. In construction products, they act as carriers for surface coatings such as paints, varnishes, adhesives and pesticides.

The most common solvents found in construction are:

White spirit - in paints, varnishes and cleaning products. Xylene - in paints, adhesives and pesticides. Butanol - in natural and synthetic resins, paints and lacquers.

Many construction products contain mixtures of solvents. Exposure to solvents can have serious effects on workers' health. If you use solvents or manage or supervise someone who does, or if you are involved in the specification of solvent-based products for use in construction, you need to be aware that exposure can be a health hazard and safe working practices must be used to minimise the risk of exposure.

This unit advises on how to use solvents safely.

Health effects.

Solvents can make you ill by:

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Breathing in vapours - paints, paint strippers and glues give off solvent vapours as they dry or cure and these vapours may be harmful. Deliberate inhalation of solvent vapours (glue sniffing) can kill.

Skin contact - some solvents can be absorbed through the skin. Repeated or prolonged skin contact with liquid solvents may cause dermatitis.

Eye contact - contact with liquid solvent and solvent vapour can cause irritation and inflammation.

Ingestion - solvents can be taken into the body on contaminated food, drink and cigarettes.

People have accidentally drunk solvents that have been kept in old, unlabelled drinks containers. The main effects of solvents are irritation of the skin, eyes and lungs, headache, nausea, dizziness and light-headedness.

Exposure can impair co-ordination and this can make people more prone to accidents such as falling off ladders. People may lose concentration on important or difficult tasks and they may react more slowly to dangerous situations. The effect can vary from person to person and will generally be made worse by drinking alcohol.

Very high exposures can cause unconsciousness and even death, for instance where adhesives are used in unventilated confined spaces or where there are serious spillages.

Other possible effects on health vary according to the solvent to which people are exposed. Anyone who has been exposed to solvents and feels that their health has been affected should seek medical advice.

1.31.1 Solvents contd

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Users will find information on the hazards on the containers but they should also get information (often as Hazard Data Sheets) from manufacturers and suppliers. Users then need to consider how those hazards can be prevented or controlled.

Designers or people who specify products for use in construction should aim to avoid risks to the health and safety of those carrying out construction work.

Where it is not possible to avoid the risk, they should specify the least hazardous products which perform to an acceptable standard. If solvent-based products cannot be avoided, the designer or specifier should provide information about safe use.

Precautions.

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Preventing exposure.

First of all, consider whether the solvent-based products need to be used at all. Can they be replaced by an alternative, less hazardous material? For example, use a water-based formulation if possible; these are widely available

.

Controlling exposure.

If solvent-based products are used, make sure the work area is well ventilated. Open doors, windows, roof lights etc to increase ventilation and make sure that they are kept open. Local exhaust (mechanical) ventilation may be necessary in some cases.

If possible, avoid spraying solvent-based products, as this causes more vapour to get into the air than using a brush.

Store solvents in properly labelled, suitable containers. Use dispensers where possible to keep evaporation to a minimum and reduce spillage. Keep lids on containers unless contents are being poured or dipped etc. Use sealed containers for solvent waste.

Dispose of solvent-soaked rags in closed containers. Train workers in how to minimise exposure and in how to deal with

spillages.

1.31.2 Spillages

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Spillages can lead to very high exposures and greatly increased fire risk. The risks from spillages and the precautions needed to deal with them should be considered in a risk assessment before the work starts.

Fire.

Many solvents are flammable. Take precautions to avoid fire and explosion risks; in particular, do not smoke in areas where solvents are used. Store products containing solvents in a secure and well-ventilated area.

Personal protective equipment (PPE).

If exposure cannot be adequately controlled in any other way, workers should wear PPE. They may need to wear one or more of the following:

Protective overalls. Appropriate gloves that have been specially selected for use with

solvents. Face shields. Respiratory protective equipment, where ventilation does not provide

adequate control.

Half-mask respirators fitted with the appropriate filter may be sufficient in many instances, but compressed airline breathing apparatus may be necessary where solvents are sprayed, or when working in a confined space.

Those who need to wear PPE should be trained in its proper use and in its limitations. Store the equipment in clean, dry conditions away from chemicals - a locker would be suitable. PPE should be maintained and kept clean and fit for wear.

Hygiene.

Good personal hygiene is very important. Facilities for washing and changing should be provided and workers should wash their hands before

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eating, drinking, smoking and going to the toilet. Eating, drinking and smoking should take place away from the work area. You should not smoke in areas where solvents are used - solvents passing through a cigarette can break down into even more harmful substances.

Articles which become heavily contaminated with solvent should be removed immediately. Overalls and contaminated personal clothing should be laundered before being re-worn. It may be necessary to air them in a safe place first, to let the solvent evaporate off. Laundering should only be done by professional cleaners who have been told of the nature of the contamination.

Thinners should not be used to remove paint or grease from the skin, as this can cause the skin to become dry and inflamed. Proper cleaning materials, e.g. soap or other cleanser, should be provided and used.

First aid.

Anyone who appears to have been affected by solvents should be taken into the fresh air immediately and given appropriate first-aid treatment. Heavily-contaminated clothing should be removed as soon as possible. Wash solvent splashes off the skin with plenty of water and cover any wounds with a suitable dressing. Splashes of solvent in the eye should be treated by washing the eye with water for at least 10 minutes before the injured person is transferred to hospital.

From the list below, what is the best way to prevent exposure to a hazardous substance?

1.   ?   Substitution for less hazardous substance2.   ?   Use PPE3.   ?   Minimise exposure

4.   ?   Dilution

1.32 Chemical Cleaners

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Introduction.

A variety of chemicals are used to clean building facades, statues, etc. These may be acid-based, e.g. hydrochloric acid (HCL), hydrofluoric acid (HF), phosphoric acid (H3PO4), nitric acid (HNO3) or alkali-based, for example caustic soda (sodium hydroxide - NaOH) or caustic potash (potassium hydroxide - KOH). This unit gives health and safety guidance for anyone who uses these materials or is responsible for managing or supervising their use.

Health effects.

Chemical cleaners can cause serious ill-health mainly by:

skin contact: acids and alkalis cause burns which are often slow to heal; and

Inhaling fumes or mist: concentrated solutions of acids and alkalis may give off toxic and corrosive fumes. Spray application produces a mist which may also be toxic and corrosive.

Concentrated solutions from which the dilute working solutions are made up pose the greatest risk but even dilute solutions can cause serious injury. This is particularly true of HF where skin contact with diluted solution can cause very serious and extremely painful burns which may not be felt until up to 24 hours after contact.

Using chemical cleaners.

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Users should get information on risks and precautions from the manufacturers or suppliers who have a legal duty to provide it.

Acids and alkalis will attack and corrode a wide variety of materials and a material resistant to one may not be resistant to another. Consult manufacturers or suppliers of any equipment used on whether it is suitable for use with chemical cleaners. With concentrated acids or alkalis, written advice should be obtained from the manufacturers or suppliers.

1.32.1 Precautionary Measures

Preventing exposure.

Consider whether corrosive chemicals need to be used at all. Those who specify construction materials have a duty to avoid risk and to get rid of hazardous materials. Where this is not possible, they should specify the least hazardous products which will perform to an acceptable standard. Contractors, who use less hazardous cleaning methods and materials can help designers in identifying these.

If corrosive acids or alkalis have to be used, choose the most dilute solution which is effective. Use proprietary brands of cleaner which are diluted by the manufacturer or supplier rather than handle concentrated chemicals yourself.

Controlling exposure.

If you have to handle and dilute concentrated acids or alkalis, dilution should take place in a well-ventilated area off-site (e.g. under controlled conditions

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in the depot) and concentrated acid or alkali transferred using sealed equipment such as a self-priming syphon or pump.

When diluting, always add acid or alkali to water, never water to acid or alkali. Transfer the dilute material to site in properly-labelled, sealed containers. If dilution on site cannot be avoided, it should always be done at ground level. Avoid spray application. Apply the cleaner with a brush or roller, fitted with a splash guard.

Personal Protective Equipment (PPE).

Wear appropriate protective clothing to protect your skin, face, eyes, etc, from the corrosive material, including:

Eye protection. Gauntlet gloves which have been properly selected and are suitable

for the task. Protective, chemical-proof and waterproof boots. Protective overalls and, when handling concentrated acid or alkalis, a

protective apron (to below top of boots). Approved respiratory protective equipment (RPE) which could be

necessary when handling concentrated acids or alkalis, cleaning by spraying or in confined areas.

Check with the manufacturer or supplier of the PPE to ensure that it is suitable for the corrosive material being used and for the working conditions. Those who need to wear PPE should be trained in its proper use and its limitations. Store the equipment in clean, dry conditions away from chemicals - a locker would be suitable. PPE should be maintained and kept clean.

1.32.2 Hygiene

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Ensure that protective equipment is thoroughly cleaned with water

after use and checked for any wear, e.g. pinholes or cuts in the gloves, especially the fingertips. All contaminated clothing should be laundered professionally by fully briefed staff before it is re-worn.

Heavily-contaminated clothing should be removed at once and washed separately. Clothing contaminated with hydrofluoric acid (HF) or other concentrated acids should be neutralised with sodium bicarbonate solution (NaHCO3) before washing (keep solution readily available if HF is being used).

Workers should avoid contact with contaminated equipment, e.g. they should not raise their face protection with soiled gloves as this can result in facial burns.

Welfare facilities should be available on site and workers should wash their hands and face at the end of each job and before eating, drinking or smoking, and wash their hands before going to the toilet. Where possible, showers should be available at the end of the day.

1.32.3 Protecting the PublicMembers of the public and workers who are not involved in cleaning need to be protected

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against exposure to the chemicals. The following steps should be taken:

(a)check all windows, doors, etc, in facades are closed to protect

the building's occupants;

(b) avoid applying or rinsing with a spray or working in windy conditions as

this may give rise to fine droplets which could be carried as a mist by the wind;

(c)create a no-go area with barriers around the base of the facade, statue etc at the same time ensuring pedestrians have a safe, alternative path to use. Suitable warning signs should be posted (the local highways authority will need to be consulted if the public pavement or roadway are involved). Drainage gullies should be covered or fenced off;

(d)scaffolding should be close-boarded and sheeted to contain splashes etc. Extra ties may be needed to counter the increased wind loading on the scaffold;

(e) open ends of scaffold poles should be capped before beginning work;

(f) over-spilt liquid should be directed so that it does not flow over the pavement (the Environment Agency, local authority and local water company should be consulted over any likely or actual pollution of water courses).

(g)

store chemical cleaners in a secure area to prevent them being accessible to members of the public. Always store acids away from alkalis;

(h)these chemicals need to be disposed of carefully and should not be put down the drain. Make arrangements with the local authority for the safe disposal of them.

1.32.4 After Treatment69

On the site, the inside and outside of scaffold tubes, fittings and boards should be washed thoroughly with clean water (but see point (h) above). Thoroughly clean all equipment with water and examine it for signs of deterioration.

Spillages.

Dilute spillages of the acid or alkali cleaners with water unless HF or concentrated acids are involved. In this case, neutralise spillages with slaked lime (calcium hydroxide - Ca(OH)2). Tools and equipment which may be contaminated should be treated similarly. Porous materials such as wood or packaging should be disposed of as contaminated waste if contaminated with concentrated acids or alkalis or HF.

First aid.

Anyone appearing to be affected by the chemical cleaners should be taken at once into the fresh air to be given first aid and referred to medical care.

In most cases, first aid will involve drenching the affected parts, e.g. skin, eyes, etc, with plenty of cool, clean water. A drench shower should be available.

HF burns require special first-aid treatment which involves applying an antidote to the burn. Contractors should inform the accident and emergency department of the local hospital that they are using HF on site. The hospital will then arrange to have the antidote available in case of an emergency. If the antidote is kept on site, first aiders will need to be specially trained in its use.

1.33 Noise70

Employers should carry out the following actions:

Decide if a noise assessment is needed.If people have difficulty speaking to each other over approximately 2 m, then you will need to make a noise assessment. This should take account of others who may be affected as well as your own employees.

Assess the noise.The assessment should be made by a competent person.

An initial, estimated assessment can be made either by using manufacturers' data or other reliable information which is available. This would be a 'first step' and would enable you to identify workers who need personal protection straight away. Also, on multi-contractor sites, the various employers will need to agree who should co-ordinate compliance with the Regulations. Usually the contractor in overall charge of the site does this.

Action levels are values of 'daily personal exposure to noise-LEP,d' which depend on working area noise levels and exposure times. The first action level is 80 dB(A),LEP,d and the second action level is 85 dB(A),LEP,d.The peak action level is the maximum pressure allowed to be reached by a sound wave, specified as 140 dB (without A weighting). This action level causes concern when cartridge tools are being used, where 140 dB could be exceeded although 80 dB(A),LEP,d has not.

Reduce noise as far as reasonably practicable.The most effective and reliable way of controlling exposure is by

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engineering measures at source. This can be achieved by making sure that noise reduction is built into machinery when you are buying it. Ask for information on machine noise before you decide to buy.

Provide ear protection.Ear muffs or ear plugs should be worn by people exposed at or above 85 dB(A),LEP,d or the 140 dB, peak action level. This is not an alternative to controlling noise at source. Between the 80 dB(A) and 85 dB(A) action levels you should make sure that ear protection is freely available and that people know that unless the protection is worn there is some risk to their hearing.

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1.33.1 Noise Continued

Ear protection is not mandatory below the second action level, but must be worn when entering an ear protection zone.

Inform workers about the level of their personal LEP,d exposureIf your noise assessment shows personal exposure at or above any of the action levels, inform your employees there is a noise hazard and tell them what you want them to do to minimise their risk of hearing damage.

Mark ear protection zones.Zones should be marked wherever employees are likely to be exposed to the second action level or above.

Employees Should: Wear ear protection (ear muffs or ear plugs) provided (in the absence

or pending noise control) whenever you are exposed at or above the second or peak action levels, as well as when entering an ear protection zone.

Use any other equipment your employer provides, eg machines fitted with silencers - don't take them off.

Take care of equipment provided. If you discover any defects reducing their performance, you should report them.

See your doctor if you think that your hearing has become damaged.

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1.33.2 Example Noise Exposures

Activity

Likely Noise Exposure

LEP,d

Average Range

Agent (up to 50% day on site) 80

Asphalt paving 85

Blasting 100+

Bricklayer 83 81-85

Carpenter 92 86-96

Concrete

chipping/drilling 85+

floor finishing 85

grinding 85+

Concrete worker 89

Crushing mill worker 85+

Driver crawler tractor 85+

dumper 85+

excavator 85

grader 85+

loader 85

roller 85+

wheeled loader 89

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wheeled tractor 85

Engineer supervising pour 96

surveying 80

Foreman supervising workers 80

Formwork setter 92 89-93

Ganger concrete pour 93 92-93

general work 94

Guniting 85+

Labourer

concrete pour 97 95-98

digging/scabbling 100

general work 84

shovelling hardcore 94

shuttering 91

M&E installer general 89 82-96

small work 84 78-89

Piling operator 85+

Piling worker 100+

Reinforcement worker building site 86 82-89

bending yard 84 77-87

Sandblasting 85+

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Excessive noise causes damage, which will not get better even if you move to quieter work. A good rule of thumb for judging whether the noise is excessive is that if you have to raise your voice to hold a conversation with someone who is at arm's length distance then the noise is probably sufficient to damage your hearing.

A guide to whether you are deaf or not is if you have difficulty following a conversation when there is background music.

Employers have a duty to protect workers from noisy processes and it is not enough to just provide hearing protection for workers. The first thing employers should do is to investigate how to make the process less noisy and only if this is not possible should they provide personal protective equipment.

Deafness is the second largest category of occupational illness but the rules for compensation are very strict so it is much better to protect your hearing while you have the chance.

1.34 Dermatitis76

The symptoms are:

affected skin gets red, sore, itchy, scaly and blistered; if it gets worse, the skin can crack and bleed, and the dermatitis can

spread all over the body (it often starts on the hands).

It is a very painful condition but it is not infectious. If it is left untreated the condition can force workers to give up their jobs, but it is preventable, and if treated early it can be cured.

Occupational dermatitis is caused when the skin comes into contact with certain substances at work. Some cause dermatitis by irritating the skin whereas others cause an allergic reaction.

The length of time it takes to develop depends on the substance, its strength and potency, and how long or how often it touches the skin.

Once someone has developed an allergic reaction, contact with even the tiniest amount can bring on the dermatitis.

The most common substances that cause building workers to contract dermatitis include:

Cement products. Latex rubber. Nickel and chromium. Epoxy and other resins. Oils, soaps and detergents. Some paints and wood preservatives.

Employers must assess the risks of work that could cause dermatitis, prevent employees coming into contact with them as far as reasonably practicable and provide those workers most at risk with regular health checks.

1.34.1 Dermatitis Continued

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Producers supplying skin sensitisers and skin irritants must label them and provide a data sheet explaining the dangers.

In addition, employers must provide sufficient washing and changing facilities for workers likely to be exposed to the causes of dermatitis.

What you should do:

Ask for health checks to be carried out by the employer and ask to see general information about the results.

Check all substances you come into contact with for labels identifying potential skin irritation.

Insist on substitute products whenever they are available. If substitution is not possible, insist on limited exposure. Ensure you receive the necessary training to reduce the risk. Ensure you are provided with proper washing facilities. Insist on free protective clothing from your employer, such as gloves. Ensure that all hazardous chemicals are stored safely.

1.35 Work-Related Asthma78

Asthma is a distressing and potentially life-threatening disease that can be caused by breathing in chemicals called sensitisers. These are substances that can trigger an irreversible allergic reaction.

Sensitisation occurs after months or years of breathing in the harmful substances. However, once asthma has developed there is likely to be permanent lung damage if there is continued exposure.

There are at least 1,000 new asthma cases each year in the UK alone, many of them building workers. It is also possible for many people to have early symptoms without realising what it is.

Things to watch for in yourself and the people you work with are coughing, wheezing, tightness of the chest, constantly runny nose with watery and prickly eyes.

Substances known to cause asthma:

Wood dusts. Epoxy resins in some glues and resins. Isocyanates in some paints. Formaldehyde in some MDF. Some paints and wood preservatives.

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1.36 Other Problems Caused by Dusts

The relationship between asbestos and cancer is well known, as is the link between hardwood dust and nasal cancer. It is common sense that breathing in dust of any type is likely to be harmful and can cause diseases such as bronchitis and emphysema.

The following dusts have Workplace Exposure Levels set by the HSE (asbestos is covered separately). This means there is no safe level:

Wood dust (hard and soft). Gypsum. Silica. Cement.

For these dusts, there should be sampling by trained technicians and engineering controls introduced to reduce dust levels, in particular local exhaust ventilation systems either serving one machine or throughout a factory. These must be regularly maintained.

Damping surfaces can help to reduce dust as can working with hand tools rather than power tools.

You should always wear the respiratory equipment that is provided and make sure that it is suitable for the job you are doing.

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1.36.1 Silica

Silica occurs as a natural component of many materials used or encountered in construction activities. This unit deals with crystalline silica which can cause lung disease.

Crystalline silica is present in substantial quantities in sand, sandstone and granite and often forms a significant proportion of clay, shale and slate. It can also be found in chalk, limestone and other rock and soil, though this is unusual. Products such as concrete and mortar also contain crystalline silica.

Exposure to silica.

The health hazards of silica come from breathing in the dust. Activities which can expose workers or members of the public to the dust include:

Stone masonry. Facade renovation. Blast cleaning of buildings, especially using sand. Many demolition processes. Concrete scabbling, cutting or drilling. Tunnelling.

The use of power tools to cut or dress stone will lead to high exposures throughout the work.

For other activities, exposure will often depend upon how confined the working space is, the presence or absence of ventilation and how near the worker's breathing zone is to the source of the dust.

Tunnelling through dry, silica-bearing rock will always lead to high exposures for workers at or near the cutting face.

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1.36.2 Health EffectsBreathing in the very fine dust of crystalline silica can lead to the development of

silicosis. This involves scarring of the lung tissue and can lead to breathing difficulties.

Exposure to very high concentrations over a relatively short period of time can cause acute silicosis, resulting in rapidly progressive breathlessness and death within a few months of onset.

Similarly, accelerated silicosis, which can progress to death within a decade, has been associated with high exposures to silica in sand blasting.

More common is progressive silicosis, usually because of exposure over a longer period. This causes fibrosis (hardening or scarring) of the lung tissue with a consequent loss of lung function.

Victims are likely to suffer severe shortness of breath and will find it difficult or impossible to walk even short distances or upstairs. The effect continues to develop after exposure has stopped and is irreversible. Sufferers usually become house or bed-bound and often die prematurely due to heart failure.

Silica may be linked to lung cancer. If this is the case, it is most likely that it occurs as a progression of lung fibrosis. Precautions taken to control the risk of fibrosis will serve to control the risk of lung cancer.

Legal requirements.

The UK EH40 2007 has assigned crystalline respirable silica a workplace exposure limit (WEL) of 0.1 mg/m-3, expressed as an 8-hour time weighted average (TWA). This means that exposure to respirable crystalline silica should be reduced so far as is reasonably practicable and, in any case, below the WEL.

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1.36.3 Precautions

Assessment

Activities which may expose workers to silica require the health risk to be assessed and then prevented or controlled. In most cases, when it is reasonable to expect dust levels to be significant, you should consider the need for atmospheric sampling of respirable dust and respirable silica.

In cases of doubt, it should usually be assumed that levels will be significant unless sampling from very similar work has shown otherwise.

Results of sampling may be needed to find out the control measures that will be appropriate for a particular activity. As well as evaluating the risk and describing the precautions, the assessment should set out in detail the way in which the control measures are to be monitored, supervised and maintained.

Prevention and control.

Elimination and substitution.

First of all, try to get rid of silica dust from your work. Sometimes silica can be eliminated by substituting other materials, for instance, using non-silica grits for blasting.

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1.36.4 Control of DustIf you cannot get rid of silica dust, you should reduce exposure. In most cases, it is feasible to control respirable silica by dust suppression techniques or local exhaust ventilation.

Exhaust ventilated tools which remove the dust at source, and tools fitted with a water supply for dust suppression, are widely available. Capturing or controlling the dust at source is nearly always better than attempting to control exposure by ventilating the whole area.

Personal protective equipment (PPE).

These control techniques may not always be appropriate or they might not reduce exposure sufficiently, so respiratory protective equipment (RPE) often has to be provided as well. You will need to select RPE very carefully as different types can give widely varying standards of protection.

Surveys of respirable dust and respirable silica levels are usually necessary to ensure correct selection.

For the dustiest processes, positive pressure or airline breathing apparatus will probably be necessary. Remember that filtering facepiece or half-mask respirators give little or no protection to men with beards and that even a minor growth of stubble can severely reduce the effectiveness of RPE.

Guidance on the selection and use of RPE is contained in the HSE booklet: The selection, use and maintenance of respiratory protective equipment: A practical guide (see References section).

Further information can be obtained from RPE manufacturers who should provide information on approval and suitability.

Remember that workers need to be properly trained in the use of RPE and that a high standard of supervision, inspection and maintenance will also be needed.

Suitable protective clothing should be provided to prevent contamination of worker's own clothing.

Those who need to wear PPE should be trained in its proper use and in its limitations. Store the equipment in clean, dry conditions away from chemicals - a locker would be suitable. PPE should be maintained and kept clean and fit for wear. Facilities for washing and changing should be available on site and workers should wash their hands before eating, drinking, smoking and going to the toilet. Eating, drinking and smoking should take place away from the work area.

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1.36.5 Health Surveillance

Where workers are regularly exposed to respirable crystalline silica levels greater than 0.1 mg/m3, 8-hour TWA, then health surveillance which includes a respiratory questionnaire, lung function testing and chest X-rays should be provided.

HSE Guidance Note Respirable crystalline silica describes health surveillance requirements in more detail.

Examples of typical levels of silica exposure in some common construction activities.

Activity Control measures Exposure Improvements required *

Drilling in poorly ventilated

● no dust suppression.

HIGH - 300 times the WEL ● fit water suppression or dust

undercroft. ● no extraction. extraction to drilling equipment

● no forced ventilation ● inadequate respiratory protective equipment (RPE)

● provide appropriate RPE ● ensure correct use of RPE

Drilling into brickwork under

● primitive extraction by fan

HIGH - 5 times the WEL ● fit water suppression or dust

arch blocked at one end. and airbag extraction to drilling equipment

● disposable face masks worn

● provide appropriate RPE

● ensure correct use of RPE

Using jackhammers to break ● limited ventilation

MEDIUM - within the WEL but

● wet down concrete and

out concrete in large open ● no dust suppression double the level regarded as

rubble

indoor area. ● no local exhaust ventilation

reasonably practicable

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● no RPE in use

Chasing out cracks in screeded cement floor in large open indoor area.

● RPE provided but not worn properly ● breathing zone of worker crouching over grinder very close to source of dust

HIGH - 6 times the WEL

● attach dust extraction to grinder ● wet down ahead of the chasing ● provide appropriate RPE

● ensure correct use of RPE

Chasing out mortar between

● ineffective extraction fitted to

HIGH - 21 times the WEL ● attach dust extraction to

bricks prior to re-pointing. hand-held electric grinder

grinder

● RPE correctly worn but not

● provide appropriate RPE

to correct standard ● ensure correct use of RPE

Cutting paving kerb (33% silica)

● petrol driven saw not fitted

HIGH - 12 times the WEL

● provide effective water

in open area. with water spray or local

suppression system to saw

exhaust ventilation

Cutting blue brick (32% silica)

● petrol driven saw not fitted

HIGH - 5 times the MEL

● provide effective water

in open area. with water spray or local

suppression system to saw

exhaust ventilation

Cutting breeze block (3% silica)

● petrol driven saw not fitted

HIGH - twice the WEL

● provide effective water

in open area. with water spray or local

suppression to saw

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exhaust ventilation

Cutting window openings in

● water suppression on saw

LOW - well below the WEL

concrete wall with wall saw/

used and also below the level

cutting concrete with floor saw.

regarded as significant

General clearing and removing rubble.

● hand sweeping with brush

HIGH - twice the WEL

● damp down rubble before clearing

● use mechanical means to

sweep up

● provide appropriate RPE

● ensure correct use of RPE

General clearing and removing

● use of mechanical sweeper

MEDIUM -within the WEL

● provide appropriate RPE

rubble. with rotating brushes and

but double the level ● ensure correct use of RPE

vacuum extraction regarded as significant

Concrete crushing from ● machine with enclosed cab

LOW - well below the WEL

demolition job for use as hard

● water jets fitted and also below the level

core. regarded as significant

* To reduce exposure to below the workplace exposure limit (WEL) and so far as is reasonably practicable.

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2.0 Summary

This summary section will refer you back to the learning outcomes and summarize the notes.

Identify the main hazards of construction and demolition work and outline the general requirements necessary to control them;

Site surveying. Clearing land. Demolition, including using explosives. Excavation. Tunnelling. Ground work hand digging, laying of pipes and

concrete. Scaffolding, tower systems and access equipment. Manual handling of bricks, timber, steel, concrete

blocks and materials. Working at heights. Working below ground. Working in confined spaces. Driving and using plant and equipment. Maintenance work and repair. Hot work, burning, plumbing, cutting, welding. Working over deep water. Using hand tools. Using power tools. Using vibrating tools. Working with substances, painting, sealing, treating,

asbestos.

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The most common causes of accidents involve:

falls; falling material and collapses; electrical shock and burns; mobile plant; manual handling.

Identify the hazards of work above ground level and outline the general requirements necessary to control them;

Working above ground level

Basic hazards of work above ground level include fragile roofs, deterioration of materials, unprotected edges, unstable/poorly maintained access equipment, weather and falling materials.

Main precautions necessary to prevent falls and falling materials, include the use of guard rails, fencing, toe boards, platforms, ladder hoops, access boards and fall arrest harnesses.

Requirements for head protection. Safe working practices for common forms of access

equipment, include scaffolds (independent tied and mobile tower), mobile elevating work platforms and ladders.

Inspection requirements for scaffolds.

Falls account for a great number of accidents in the construction industry; 50% of those killed are due to falls from a height. All too often, the correct equipment may have

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been provided but not properly used.

The safety rules you might consider for the prevention of falls would include:

No work at height unless it is essential and work at height is unavoidable.

Ensure that the working platform, of whatever type, is safe and secure, checking that it is strong enough to support the weight of the worker(s) and any equipment that they may be using.

Check also that it is stable and will not overturn (for example: all types of scaffolding needs to be tied to a supporting structure) the ground is stable and will support the structure.

Provide guard-rails and barriers at all openings on floors, close to edges on roofs on working platforms.

Describe the safe working practices for common forms of access equipment;

General Access Scaffold

The main hazard for the worker on site is falling from - or through - the scaffold. The provision of guard rails is essential. The top guard rail must be a minimum of 910mm above the edge from which any person is liable to fall; usually, this will be positioned at 1000mm (1m) high by most scaffolders. Note that this measurement of 1m ties in with most proprietary scaffold systems, e.g. kwik-stage, cuplock, etc. To prevent falls whilst kneeling, an intermediate guard rail must be provided whereby there shall not be an unprotected gap exceeding 470mm between any guard rail, toe-board, barrier or any similar means of protection.

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To prevent injury to those passing below, scaffold toe-boards or other similar means of protection shall not be less than 150mm high to prevent loose material, etc., being dislodged and falling onto any person below. Usually, this will be achieved by placing a scaffold board on edge.

The safe erection of the scaffold depends upon certain factors:

1. The strength and stability of any surface upon which it is placed.

2. The stability of any structure to which the scaffold is secured.

3. The integral strength achieved by all the component parts, e.g. ledgers, bracing, etc.

4. The safety of the working platform that shall not be less than 600mm wide.

5. No gaps in the surface giving rise to injury.

6. The risk of slipping.

7. Ensuring that persons cannot become trapped between the scaffold and any adjacent structure.

8. Provision of reasonable hand-holds.

9. Ensuring that the scaffold is not overloaded to cause danger of collapse or deformation.

These general principles can be applied to any place of work.

Alternative Scaffolds

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Scaffold towers offer an alternative to general access scaffolds for short-term work. Traditionally, they were made of scaffold components and the same principles apply as for scaffolding. Sometimes, the towers need to be mobile and they can be fitted with castors which must have the facility to be locked when stationary and the tower is in use.

For stability, the height/least base ratio should not be greater than the following:

1. Static internal tower 4:1

2. Static external tower 3.5:1

3. Mobile internal tower 3.5:1

4. Mobile external tower 3:1.

The height to be measured in the above ratios is to the platform level.

The recommended maximum free standing height for static towers is 12 metres and for mobile towers 9.6 metres. Ladder access should be vertical and lashed to one of the narrowest sides, preferably inside the base area, with the ladder resting on a transom tube.

Prefabricated towers are more common these days and there are several different types of towers available which are comparatively easy to erect and offer an excellent alternative to traditional scaffolding. These towers are also mobile and will normally be prefabricated aluminium. The lightness of the material makes them easier to erect, rather than traditional steel scaffolding. In either form, competent and trained personnel are required to erect the tower.

Ladders

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The majority of access from one level to another in the construction industry is by ladder. This creates the possibility for a variety of hazards which include incorrect specification (i.e. the ladder is too long, too short, not strong enough for the task), poor maintenance (ladders can fall into disrepair and rungs can become loose or warped), poor use (ladder is not secured properly, etc.) and poor placement (traffic could cause the ladder to be knocked), all of which could result in serious injury. Apart from falls, other risks include electrical shock by using a metal ladder too close to electrical cables which could result in death. Access can be achieved safely, providing the basic requirements described in the checklist below are followed.

Safe Use of Ladders

All ladders should be in good order. If faulty, they should be scrapped.

Ladders should be placed on a firm, level base. They should be equally supported on each stile (side of

the ladder). They should be lashed or secured near the top to some

convenient secure anchorage to prevent the base from slipping outwards and the top from sliding sideways. Only the stiles should be lashed and each stile should be lashed separately.

The correct slope for a ladder is about 75°to the horizontal, i.e. 1 metre out at the base for every 4 metres of height.

If no other means of fixing a ladder to prevent slipping can be found, then someone must hold it at the base when it is being used - but this is only effective to a height of 6.0 metres.

Ladders should always be placed so that there is space behind each rung for a proper foothold. Particular care should be taken at this point on the landing platform.

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The ladder should protrude approximately 1 metre above a platform to afford a safe handhold when stepping off.

A ladder may be used for short-term work; however, it should not involve stretching to reach any work. The ladder must be secured to prevent slipping and a good handhold must be available.

For short-term work, an extension ladder may be more suitable and give greater flexibility.

Short-term work is normally deemed to be less than half an hour. For any ladder work, a risk assessment should be undertaken. This should identify a safe method of work using a work platform.

Identify the hazards of excavations and outline the general requirements necessary to control them;

Hazards & Controls Associated with Excavation Work

A range of proprietary trench boxes and hydraulic wallings allow trench supports to be put in place without requiring people to enter the excavation.

Prevent the sides and the ends from collapsing by battering them to a safe angle or supporting them with timber, sheeting or proprietary support systems.

Do not go into unsupported excavations. Never work ahead of the support. Remember that even work in shallow trenches can be

dangerous. You may need to provide support if the work involves bending or kneeling in the trench.

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Materials falling into excavations.

Do not store spoil or other materials close to the sides of excavations. The spoil may fall into the excavation and the extra loading will make the sides more prone to collapse.

Make sure the edges of the excavation are protected against falling materials. Provide toe boards where necessary.

Wear a hard hat when working in excavations.

People and vehicles falling into excavations.

Where there is risk of injury, take steps to prevent people from falling into excavations i.e. provide substantial barriers, e.g. guard rails and toe-boards.

Keep vehicles away from excavations wherever possible. Use brightly-painted baulks or barriers where necessary.

Where vehicles have to tip materials into excavations, use stop-blocks to prevent them from over-running. Remember that the sides of the excavation may need extra support.

People Being Struck by Plant

Keep workers separate from moving plant such as excavators. Where this is not possible, use safe systems of work to prevent people being struck.

Plant operators should be competent.

Undermining nearby structures.

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Make sure excavations do not affect the footings of scaffolds or the foundations of nearby structures. Walls may have very shallow foundations which can be undermined by even small trenches.

Decide if the structure needs temporary support before digging starts. Surveys of the foundations and the advice of a structural engineer may be needed.

Avoiding underground services.

Look around for obvious signs of underground services, e.g. valve covers or patching of the road surface.

Use locators to trace any services. Mark the ground accordingly.

Make sure that the person supervising excavation work has service plans and knows how to use them. Everyone carrying out the work should know about safe digging practices and emergency procedures.

Access.

Provide good ladder access or other safe ways of getting in and out of the excavation.

Fumes.

Exhaust fumes can be dangerous. Do not site petrol or diesel-engined equipment such as generators or

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compressors in, or near the edge of, an excavation unless fumes can be ducted away or the area can be ventilated.

Protecting the Public

Fence off all excavations in public places to prevent pedestrians and vehicles falling into them.

Where children might get onto a site out of hours, take precautions (e.g. backfilling or securely covering excavations) to reduce the chance of them being injured.

Supervision.

A competent person must supervise the installation, alteration or removal of excavation support.

People working in excavations should be given clear instructions on how to work safely.

Inspecting excavations.

A competent person must inspect excavations: at the start of each shift before work begins; after any event likely to have affected the strength or

stability of the excavation; and after any accidental fall of rock, earth or other material.

A written report should be made after most inspections. Stop work if the inspection shows the excavation to be unsafe.

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Underground work accidents generally involve one or more of the following:

Trench collapse because of inadequate side support. Undermining of nearby structures. Falls into the excavation of people, materials or

vehicles. Contact with buried underground services. Toxic gases from natural decay of vegetation etc. or

toxic exhaust fumes from petrol or diesel equipment.

Groundwork has to be properly planned and carried out to prevent accidents. Soil tests or trial holes may be required to determine the conditions likely to be found on the site, particularly - of course - for larger excavations.

The collapse of excavations can be prevented in two ways: Battering, i.e. having angled sides to the excavations

(very shallow in the case of powdery soils or where wet conditions may make the soil mobile), or if this is not possible,

supporting the (vertical) sides of the excavation

For the latter, many types of system are available - timbering and props, pre-fabricated boxes which are lowered into the excavation, trench sheeting systems, which are sections of shaped metal sheet that can overlap at their edges to provide shoring support.

Above all, groundwork needs to be planned, undertaken and maintained by people with suitable expertise. The CDM Regulations, to which we will soon briefly return, provide a framework for the management of the work.

As far as the undermining of nearby structures is concerned, it should be remembered that many walls, particularly boundary walls, have very shallow foundations indeed.

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Excavations must be guarded appropriately. Remember that ground level working can become working at height in the proximity of an excavation.

All excavations in public places should be suitably fenced off to prevent members of the public approaching them. Vehicles must be kept away from the excavation unless they have to approach for the purposes of material delivery and removal; in such situations, they must use approved routes which will bear their weight, stop blocks will be required to prevent over-running into the excavation.

Similarly, areas close to the sides of excavations must never be used for storing spoil and other materials or for parking plant and vehicles.

Underground services - gas, water and electricity - can be easily damaged during excavation work, leading to electrocution, fire, flooding and interruption of services to hospitals, offices and so on. Ideally, excavations should be kept away from existing under ground services; these can be identified by a combination of:

Clues provided by manhole covers, street lights etc. Cable and other service plans of the area. Detection devices (conventional detectors will miss plastic pipes). In practice, excavations may have to be made in areas where there are

known to be existing and/or disused services. Safe practices must be employed once the digging actually starts.

Watch carefully for evidence of previously unknown pipes or cables - check using the detection device.

Dig trial holes by hand to confirm the position of pipes and cables - this is particularly important where plastic pipes are used.

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Dig by hand near buried pipes or cables, using spades and shovels rather than picks and forks.

Treat all pipes and cables as live unless known otherwise Report any suspected damage to services Ensure there is an emergency plan to deal with damage to cables or

pipes. Update service plans for the benefit of those in the future.

Chemical hazards may be encountered in excavation work; fumes or exhaust gases from equipment can collect and accumulate in excavations and pose serious hazards.

In deep excavations, particularly in areas such as river-beds and estuaries, it may be necessary to use gas detection equipment to ensure that toxic or explosive levels of decomposition gases are not building up.

At the start of each shift or after any event that may have affected their strength or stability, the excavations and supporting system should be inspected.

Construction Activities (Cont.)

Congratulations - end of lesson reached

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