1.0 Unit 15:

Physical and Psychological Health Hazards and Control

Understand

the ill-health effects of the physical process of work and of the working environment;

the available control options to combat these risks in the workplace.

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The intended learning outcomes of this element are that candidates will be able to:

explain the term 'ergonomics' and the contribution that ergonomic design can make to health, safety and efficiency at work;

identify work processes and practices that may give rise to musculoskeletal health problems (in particular work-related upper limb disorders - WRULDs) and hand/arm vibration syndrome (HAVS);

illustrate the nature and extent of musculoskeletal effects with reference to the use of display screen equipment (DSE);

identify common welfare and work environment requirements in the workplace; describe the health effects associated with exposure to noise and suggest appropriate

control measures; describe the principal health effects associated with ionising and non-ionising

radiation and outline basic protection techniques; explain the causes and effects of stress at work and suggest appropriate control

actions; describe the situations that present a risk of violent assault to workers and suggest

ways of minimising such risk.

Reference:

Ambient factors in the Workplace (ILO Code of Practice), ISBN 922 11628-X.

A Pain in Your Workplace? Ergonomic Problems and Solutions (HSG121), HSE Books Display Screen Equipment Work (Guidance) (L26), HSE Books.

Lighting at Work (HSG38), HSE Books.

Personal Protective Equipment at Work (Guidance) (L25), HSE Books.

Seating at Work (HSG57), HSE Books.

Ergonomic Checkpoints, ILO 'I ii Work Organisation and Ergonomics, ILO.

Tutition time: 7 hours.

1.2 Introduction to Physical, Psychological & Ergonomic Health Hazards and Control

Within unit 12, we talked about Chemical & Biological Health Hazards.Within this unit, we will further add to Health Hazards by looking at:

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physical health hazards; psychological health hazards; ergonomic health hazards.

Physical agents include heat and cold, noise, radiation, electricity and other dangers. Physical agents can occur naturally or can be produced in the workplace. For example, heat is a physical agent that is the result of the weather and is also produced in kitchens and laundries.

Protecting workers from physical agents requires the same process as other hazards. First, the physical agent and its health effects must be identified. Next, working conditions must be changed to prevent exposure to the hazards. Within this unit, we will describe how to protect employees from common physical agents.

Psychological health hazards include Fatigue, Stress, Shift Work and Violence.

Ergonomic health hazards include Manual Handling, Production Processes and arise from use of a Visual Display Unit (VDU).

1.3 Task and workstation design

Ergonomics is a branch of science that aims to learn about human abilities and limitations and then apply that knowledge to improve people's interaction with products, systems and environments.

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Ergonomics is a relatively new branch of science which celebrated its 60th anniversary in 2009 but relies on research carried out in many other older established scientific areas, such as engineering, physiology and psychology.

It originated in World War 2, when scientists designed advanced new and potentially improved systems without fully considering the people who would be using them.

It gradually became clear that systems and products would have to be designed to take account of many human and environmental factors if they were to be used safely and effectively. This awareness of peoples requirements resulted in the discipline of ergonomics.

Most people have heard of ergonomics and think it is something to do with seating or with the design of car controls and instruments. This is only a small part of its remit - it covers a great deal more.

Ergonomics is the application of scientific information concerning humans to the design of objects, systems and environment for human use.

Ergonomics comes into everything which involves people. Work systems, sports and leisure, health and safety should embody all ergonomics principles if well-designed.

Some years ago, researchers compared the relative positions of the controls on a lathe with the size of an average male worker. It was found that the lathe operator would have to stoop and move from side to side to operate the lathe controls. An ideal sized person to fit the lathe would be just 4.5 feet tall, 2 feet across the shoulders and have an arm span of 8 feet.

This example epitomises the shortcoming in design when no account has been taken of the user. People come in all shapes and sizes, and an ergonomist takes this variability into account when influencing the design process.

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In addition to physical size, ergonomists look at strength, compatibility of controls, vision, sound, thermal comfort, motion, vibration and workloads.

Vision is usually the primary channel for information, yet systems are often so poorly designed that the user is unable to see the work area clearly. Many workers using computers cannot see their screens because of glare or reflections. Others, doing precise assembly tasks have insufficient lighting and suffer eyestrain and reduced output as a result.

Sound can be a useful way to provide information, especially for warning signals. However, care must be taken not to overload this sensory channel. Recently, it was discovered that an airliner had 16 different audio warnings, far too many for a pilot to deal with in an emergency situation. A more sensible approach was to have just a few audio signals to alert the pilot to get information guidance from a visual display.

Motion and vibration can have a detrimental effect upon the worker's efficiency, health and comfort, ranging from motion-sickness in vehicles to white finger for vibrating hand tool users. Chemicals, pollutants and Sick Building Syndrome also need to be taken into account in many working situations.

The ergonomist's role is to study all aspects of the working situation and to fit the job to the human's attributes.

1.3.1 What do Ergonomists do?Ergonomists use information about people, for example, their size

(height, weight etc.), their ability to handle information and make decisions, their ability to see and hear and their ability to work in extremes of temperature.

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Ergonomists study the way that these things vary in a group of people. With this information, the ergonomists, working with designers and engineers, can ensure that a product or service can be used comfortably, efficiently and safely.

This must be not only for 'average' people but also for the whole range of people who use the product - including perhaps, children, the elderly and the disabled.

Ergonomists can also assess existing products and services, showing where they fail to 'fit' the user (in every sense of the word) and suggesting how this fit may be improved.

1.3.2 Age-Related DesignThe number of people in the UK aged 75 and over is forecast to double

over the next 50 years. As such, there is a need to extend the range of application of equipment, services and systems designed for the general population.

Data need to be available on relevant aspects of the capability of the whole population, including older and disabled people. The aspects include the physiological (for instance, range of limb movement, strength, vision and hearing) and the psychological (for example, cognitive, reaction time, memory).

Anthropometric data are also required (size and shape ranges of people). With data such as these available, a knowledge base can be generated for access by conscientious designers.

1.3.3 The Built Environment

This includes design of the home, design of public access buildings, public spaces, and design and operation of transport systems.

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Physical aspects of design that need to be considered include stairs and ramps, hydrothermal conditions (cold, damp, heat), security and accessibility.

Sensory aspects include acoustics, lighting, comfort, communication systems, signs and navigation.

Quality of life for older and disabled people may also be enhanced by improvements in the built environment.

Why is the video recorder one of the most frustrating domestic items to operate?

Why do some car seats leave you aching after a long journey?

Why do some computer workstations confer eyestrain and muscle fatigue?

Such human irritations and inconveniences are not inevitable. Ergonomics is an approach which puts human needs and capabilities at the focus of designing technological systems.

The aim is to ensure that humans and technology work in complete harmony, with the equipment and tasks aligned to human characteristics.

Ergonomics has a wide application to everyday domestic situations but there are even more significant implications for efficiency, productivity, safety and health in work settings.

For example:

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Designing equipment and systems - including computers - so that they are easier to use and less likely to lead to errors in operation. This is particularly important in high stress and safety-critical operations such as control rooms.

Designing tasks and jobs so that they are effective and take account of human needs such as rest breaks and sensible shift patterns as well as other factors such as intrinsic rewards of the work itself.

Designing equipment and work arrangements to improve working posture and ease the load on the body, thus reducing instances of Repetitive Strain Injury/Work Related Upper Limb Disorder.

Information design, to make the interpretation and use of handbooks, signs and displays easier and less error-prone.

Design of training arrangements to cover all significant aspects of the job concerned and to take account of human learning requirements.

The design of military and space equipment systems; an extreme case of demands on the human being.

Designing working environments, including lighting and heating to suit the needs of the users and the tasks performed. Where necessary, design of personal protective equipment for work and hostile environments.

In developing countries, the acceptability and effectiveness of even fairly basic technology can be significantly enhanced.

The multi-disciplinary nature of ergonomics (sometimes called Human Factors) is immediately obvious.

Ergonomists work in teams which may involve a variety of other professions: design engineers, production engineers, industrial designers, computer specialists, industrial physicians, health and safety practitioners and specialists in human resources.

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The overall aim is to ensure that our knowledge of human characteristics is brought to bear on practical problems of people at work and in leisure.

We know that in many cases, humans can adapt to unsuitable conditions but such adaptation leads often to inefficiency, errors, unacceptable stress and physical or mental cost.

1.4 Ergonomic Hazards

It has recently been estimated by the Trades Union Congress (TUC) that over 150,000 people each year suffer symptoms of repetitive strain injury (RSI) or work related upper limb disorder (WRULD) in the UK.

However, in the past year, only 3,000 people managed to make a successful case for compensation.

For every person who wins compensation for RSI, another fifty suffer in silence, according to the TUC. Therefore, the number of workers receiving compensation for RSI is believed to be the tip of the iceberg, compared with the number actually suffering.

According to the TUC, British business loses £1 billion a year through loss of production and skilled workers. Most compensation awards include only £2,500 - £7,500 for pain and suffering in addition to loss of earnings and the cost of future care.

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The workers known to be most at risk are those on small assembly lines (for example, doing rapid packaging or food processing) and those using a keyboard and/or mouse (such as typists, journalists and office workers).

In a recent Health and Safety Executive study (quoted by the Labour research department), it was found that there was a particularly high prevalence of these disorders among keyboard users.

In the study, almost 55% of the workers had had problems with RSI at some time, and 49% had experienced symptoms in the past three months.

As well as costing business dearly, RSI or WRULD can affect individuals' lives causing much pain and disability and could possibly even put an end to their chosen career.

Much of the suffering and cost is avoidable through good workplace design, teaching employees how to set up their workstations correctly, encouraging good working practice, such as regular breaks or periods of different work, and providing prompt rehabilitation for workers reporting symptoms.

Moreover, it is now well recognised that factors such as work rate, a lack of control over the process, tight deadlines and other factors causing mental stress for operators can also increase the likelihood of an operator developing RSI or WRULD.

1.4.1 Ergonomic Injuries - Common Terminology:

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Repetitive Strain Injuries (RSIs)

Work Related Upper Limb Disorders (WRULDs)

Musculoskeletal Disorders (MSDs)

1.4.2 Definitions RSI, WRULD & MSD

WRULDs are also called ULDs (Upper Limb Disorders), RSI (Repetitive Strain Injuries), or MSDs (musculo-skeletal disorders). It is a somewhat vague term under which a large variety of conditions and symptoms are classed.

A fundamental distinction can be made between those conditions with a specific recognised medical diagnosis and those of a so-called 'diffuse' nature which still lack a clear-cut diagnosis.

Within the first category, the non-diffuse group, the following conditions are frequently encountered:

carpal tunnel syndrome; tendonitis; tenosynovitis; de Quervain's syndrome; tennis elbow; thoracic outlet syndrome and others.

All these are 'classic' conditions, well-recognised, with prescribed clinical tests and clear-cut associated symptoms.

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This is in contrast to the diffuse group of conditions, which largely escape the clinical tests and sophisticated medical investigation. The factors that are consistent in this group are:

similarities in individuals' causative history; similarities in individuals' symptoms and symptom behaviour; often disappointing results to non-diffuse type treatment.

The diffuse group of conditions is characterised by a range of symptoms (ache, pain, tingling, cramps, numbness, heaviness, tightness and others) which tend to vary in location, intensity and nature.

It is typical for symptoms to 'jump around' and once established, to appear spontaneously without obvious trigger or cause. Symptoms are often felt 'deep' in the tissues and can be hard to describe by those who experience them.

Another aspect can be the emergence of symptoms generally associated with the sympathetic nervous system. Examples include the reporting of heaviness, hands feeling hot or cold, swelling and tightness, usually without any visible signs.

In contrast with conditions such as 'tennis elbow' and carpal tunnel syndrome, the structure at fault is not easily identifiable.

Difficulties with diagnostic tests and changing symptoms have in the past led some people to believe that this condition is predominantly 'in the mind' rather than reflecting a physical injury.

Even though psychological factors do play a role, recent research has clearly identified measurable nerve function deficits.

1.5 Risk Factors

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In spite of the wealth of information and opinions on diffuse WRULDs, the current medical understanding of exactly how this condition is caused, what the damage consists of and how to determine a prognosis, is still very limited.

However, 3 groups of risk factors have been identified and are generally accepted as such.

These are:

static muscle loading; overuse and repetition; stress.

These risk factors are identical for both the diffuse and the non-diffuse conditions.

There is anecdotal evidence to suggest that people using the keyboard and mouse are more likely to develop a diffuse condition.

Those working in an industrial setting seem to be more likely to develop a more specific form of WRULD. This is likely to be related to the different 'mix' of risk factors in these settings.

1.5.1 Static Muscle LoadingStatic muscle loading describes muscular activity which focuses on holding an object or on maintaining a certain posture or position which involves little or no movement.

The problem with this form of activity is related to the muscle structure and the way muscles work.

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For muscles to be able to contract, they require energy in the form of adenosine triphosphate (ATP) which is delivered to them via the blood circulation. When muscles contract, they effectively compress the blood vessels which feed them and if a contraction is maintained for any length of time, as during static activity, their blood supply is reduced and a build-up of waste products can accumulate

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This results in muscle fatigue and can be experienced as an ache or discomfort.

Computer work tends to be more static and less varied than clerical or administration work and can cause static muscle loading in a variety of body areas unless regular breaks and changes in activity occur.

When using the keyboard, static muscle work is required to hold the arms and hands in place.

Furthermore, if the back is not well supported, static muscle activity will occur there and in the muscles of the neck.

Over time, this can lead to localised muscle tightness and postural imbalances, which can compromise the blood supply and the nerve function in the arms and hands.

1.5.2 Overuse and RepetitionOveruse of specific muscles and repetition of certain activities can carry

the risk of straining tissues beyond their normal capacity.

Initially, fatigue occurs and - if demands increase, or sufficient changes in activity or breaks are not provided - then aches, pains and injury can result.

Any repetitive task performed continuously, without sufficient breaks or changes in activity, will place demands on specific structures and result in

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a risk of injury.

The way in which an activity is performed will affect the likelihood of a problem occurring.

As an example, we can use the angle of the wrist while typing or using the mouse. With the wrists in a neutral position, the risk of an overuse problem is greatly reduced compared with typing or using the mouse with wrists extended or deviated. This is due to the affected structures working in a neutral, relaxed position, causing minimal compression or stretch and requiring minimal effort and muscle activity.

1.5.3 StressStress and other psychological factors, perhaps surprisingly, can play an important part in the onset and experience of WRULDs too.

This is due to stress causing increased muscle tension and generally sensitising the nervous system, which leads to an increased perception of pain.

Stress factors, whether related to work, family or any other area, can therefore be important contributors to WRULDs.

The reason why this condition has been particularly prominent among computer users is probably due to the fact that often all three of these risk factors are present in the modern office environment.

1.5.3.1 Video : Work Stress to lift balance

1.5.4 RSI, WRULD & MSD Risk Factors

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Each of the risk factors described here can cause problems. However, it is usually the case that workers are exposed to more than one risk factor at a time.

Repetitive motion: This refers to performing the same motion or motion pattern every few seconds or on a continuous basis for hours at a time.

Awkward posture: Whether standing or sitting, there is a neutral position for the back, neck, arms and hands. This is the position that puts the least amount of physical strain on the particular part of the body. Postures that differ from the neutral position increase stress on the body.

Figure 1

Overhead work, twisted or bent back, bent wrists, squatting or stooping are examples of body positions and movements that cause problems. (Figure 1).

Long periods of repetitive activity (duration): This is the amount of time workers perform a motion or movement pattern during the workday.

Lack of recovery time: Recovery is rest or a break from a risk factor. Forceful movement: This is the effort or pressure workers need to

perform various tasks. Forceful movements include lifting a heavy object, unscrewing a rusted bolt or squeezing an object in your hand.

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Another type of force, known as contact stress, comes from pressure against a part of the body. For example, resting the wrists against the sharp edge of a desk while working at a computer puts pressure on the wrists.

Vibration : Exposure to vibration can affect particular parts of the body, such as the hands, when using power tools. This is known as localised vibration. Workers who drive trucks or work with jackhammers are exposed to whole body vibration.

Uncomfortable environmental conditions: An uncomfortable environment can be dangerous as well as unpleasant. High temperature and humidity can make workers drowsy and less alert. Excessive noise damages hearing. Glare and bright lighting while working with computers can cause headaches and vision problems.

Stressful work organisation: This refers to the way jobs are organised. These factors include staffing levels, scheduling workload and job pacing, electronic monitoring, performing monotonous tasks and the amount of control workers have over how they perform their jobs. These are sometimes called psychosocial factors.

1.5.5 Injuries Caused by Poor Ergonomics

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Carpal Tunnel Syndrome.

This is a painful condition of the hands and wrists caused by pressure on the median nerve, which runs from the shoulder down the arm to the hands.

Symptoms: In addition to pain, the symptoms of carpal tunnel syndrome include numbness, tingling and weakness in the hands. These symptoms are usually felt in the first three fingers and the base of the thumb. Often the pain and other symptoms are worse at night or during sleep. It can occur in one wrist or both (bilateral carpal tunnel). In advanced cases, carpal tunnel syndrome can make common activities impossible, such as holding a frying pan, folding laundry or lifting an infant. See Figure 2.

1.5.6 Risk Factors18

The major causes of carpal tunnel syndrome are:

working with wrists that are bent; a high rate of repetition using the hands; a lack of rest for the hands and wrists, and forceful hand motions.

The table below lists common ergonomic injuries of the hands, arms and shoulders.

Common Repetitive Strain Injuries

Repetitive StrainInjury

Symptoms Risk Factors

Carpal Tunnel Syndrome pain, numbness, tingling in the hands, weaknessand clumsiness of the hands.

repetition, working with wrists bent, and/or forceful hand movements.

Ganglion Cysts 

swelling that forms a lump on the wrist.

repetition and working with wrists bent.

De Quervains Disease pain and inflammation at the base of the thumb.

repetition of a clothes-wringing motion.

Raynauds Syndrome/White Finger

loss of control and feelingin fingers and hands, numbness or tingling in the fingers.

forceful gripping, vibration, cold and/or wet environment.

Trigger Finger pain and inflammation on the palm side of index finger.

forceful gripping of hard/sharp edges, repetition.

Tendinitis pain and inflammation in any joint such as elbow, wrist, knee, etc.

repetition and awkward posture.

Tennis Elbow(epicondylitis)

pain and inflammation in elbow. repetition, rotation of forearm, or force.

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Rotator Cuff/Tendinitis pain and restricted motionin shoulder, may lead toarthritis.

repetition, overhead work, or working with arms in a winging motion.

Loss of control and feeling in fingers and hands, numbness or tingling in the fingers is a symptom of

1.   ?   Tendinitis2.   ?   All of these3.   ?   Raynaud's Syndrome (white finger)

4.   ?   Carpal Tunnel Syndrome

Risk factors which increase the likelihood of WRULDS & MDS include ......

1.   ?   All of the above2.   ?   Awkward positions3.   ?   Vibrations

4.   ?   Repetitive motion

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1.5.7 Lower Back ProblemsPain in the lower back, or lumbar region, is the most common work-related back problem. Low back pain occurs due to a variety of injuries and illnesses. Muscles and ligaments in the back can be injured and cause pain.

Injuries and illnesses affecting discs and nerves are also very painful. Discs can deteriorate, or a disc can stick out and press on nerves. This condition is called a prolapsed disc, which is sometimes called a slipped disc. Problems with the spinal column can also cause pressure on nerves.

Lifting, pulling, pushing, bending and twisting are factors that cause lower back pain. These movements involve the risk factors of force, repetition and harmful posture. Vibration is another condition that can lead to back pain.

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1.6 Steps to Solving Ergonomics Problems

Implement an ergonomics programme.

Form an Ergonomics Team.

An ergonomics team should be made up of representatives from labour and management. It should also include individuals who are knowledgeable about ergonomics and the medical treatment of ergonomic injuries.

A comprehensive ergonomics programme includes:

training to increase ergonomic awareness and build in-house expertise; collecting information on employee injuries and discomfort; identifying risk factors in the workplace that are causing injury and

discomfort; giving workers input into how they do their jobs; developing ways to control ergonomic hazards by modifying

equipment, the office environment and the organisation of work; implementing a medical management programme to identify RSIs early

and ensure appropriate medical treatment; identifying or creating light duty positions and making other job

accommodations; evaluating the effectiveness of the ergonomics programme.

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1.6.1 Finding Ergonomic Injuries and their Causes

Raise Awareness of Ergonomics by Training Workers and Supervisors.

Workers and their supervisors should receive training about the causes and prevention of RSIs. The training should cover:

signs and symptoms of RSIs; use and adjustment of equipment; breaks and other ways to reduce the amount of time they are exposed to

ergonomic risks; activities such as stretching and life style changes that reduce the risk of

RSIs; reporting symptoms to the employer's designated person; procedures to request an ergonomic evaluation of their job, of the

equipment, getting medical help or other policies.

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1.6.2 Collect Information on Employees Injuries and Discomfort

Find out which workers have been injured or are having pain. The information can be obtained by:

looking for repetitive strain injuries in the OSHA 200 log; checking workers' compensation records; conducting a survey of symptoms.

1.6.3 Identify Risk Factors in the Workplace that Cause Injury and

DiscomfortA job analysis means taking a close look at a job to see what conditions are causing problems. It is important to look at all the tasks that are part of a job. For example, to find the cause of carpal tunnel syndrome for library clerks, the job analysis should look at computer work, book handling and other repetitive tasks performed with the hands. A sample job analysis checklist for computer operators is below.

The main risk factors to look for are:

repetitive motion; awkward posture; long periods of repetitive activity (duration); lack of recovery time; forceful movement;

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vibration ; uncomfortable environmental conditions; stressful work organisation.

1.6.4 Develop Ways to Control Ergonomic Hazards by Modifying Equipment and the

Organisation of Work

As with chemical or other hazards, management should eliminate ergonomic hazards with equipment that gets rid of the risk. Other control measures include work organisation and training.

1. Equipment can control ergonomic risks.

The following are examples of equipment that can get rid of or reduce ergonomic risks:

patient lifting devices (Figure 5); transfer boards to move patients from beds; truck with hydraulic tailgate (Figure 6); adjustable computer and furniture (Figure 7); tools with bent handles, allows worker to keep wrists straight (Figure 8).

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Figure 6

Figure 5

1.6.5 Develop Ways to Control Ergonomic Hazards by Modifying Equipment and the Organisation of Work. (continued)

Interactive Display Screen Equipment Presentation

Please follow the in-presentation instructions

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1.6.6 Develop Ways to Control Ergonomic Hazards by Modifying Equipment and the Organisation of Work (Continued)

2. Work organisation changes.

The way work is done can be changed without requiring different equipment. Here are some examples:

Buy supplies in smaller containers to reduce the weight of materials that must be lifted.

Have a lifting team move patients. Take frequent rests from using the keyboard and mouse.

Rotate jobs.

Figure 8

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1.6.7 Develop Ways to Control Ergonomic Hazards by Modifying Equipment and the Organisation of Work (Continued)

2. Use safe lifting techniques to prevent back injuries.

Before lifting, make sure your path is dry and clear of objects that could cause a fall.

Bend your knees and keep your back straight (lift with your legs, not your back.)

Bring the load close to your body. Lift in a slow, even motion. Dont twist your body. If you must turn, move your feet. Keep your back straight when putting down the load.

WARNING Safe lifting techniques are not enough to prevent back injuries. Using safe lifting techniques is often not practical, especially when lifting patients. Also, the greatest cause of back injuries is total weight lifted. When people are lifting too much, even using proper techniques may not prevent a back injury.

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1.6.8 A complete ergonomics programme includes:

o Training workers and their supervisors about ergonomics.

o Collecting information on injuries and symptoms. o Evaluating jobs to find the working conditions that

are causing problems (job analysis). o Changing equipment and the way work is done to

prevent or reduce injuries. o Giving workers input into how they do their jobs. o Providing the right medical treatment to injured

workers as early as possible. o Identifying light duty positions and making other job

accommodations. o Keeping track to see if there are fewer injuries and

symptoms.

1.6.9 Video: Ergonomics

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1.7 Hand/arm vibration syndrome (HAVS)

What is it?

HAV is vibration which can reach your hands when you are working with hand-held power tools, such as chainsaws, or hand-guided machinery such as buffing machines, or when holding materials which are being processed by machinery.

What are the effects?

HAV can cause damage to:

Blood circulatory system, vibration white finger (VWF) often occurs when fingers or the body are cold or wet, initially finger tips become white. They may become numb and you may get 'pins and needles'.

Damage to nerves, causing reduction in sense of touch and temperature, and possibly permanent numbness or tingling in your fingers.

Damage to muscles, bones and joints. You may notice loss of strength in you hands and pain in your wrists

and arms. You may have difficulty in picking up small objects such as screws or nails.

The symptoms can limit what you do at work and leisure.

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1.7.1 What are the Causes of HAV?

The high levels of vibration emitted when using common tools can cause permanent damage to your hands and arms. The risk depends on:

how high the vibration levels are; how long you use the equipment for; how awkward it is for you to use the equipment; how tightly you have to grip the equipment; how cold and wet you get when using the equipment.

Employees should be aware of any tingling or numbness in fingers during or immediately after use of a vibrating tool or machine.

The problems can appear after months or years of use and depend on what levels have been experienced and for how long.

Who is most at risk?

Employees who regularly use vibrating tools and equipment in areas such as grounds, maintenance, agriculture, farms, workshops and engineering processes and those involved in cleaning activities.

In particular, individuals using tools with a hammer action for more than half an hour each day or using rotary or similar action equipment for more than 2 hours a day.

1.7.1.1 Video : HAVS

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1.7.2 What Sort of Equipment can Cause HAV?

Examples include chainsaws, circular saws, hand-held grinders, hand-held sanders, nut runners, powered lawnmowers, strimmers/brush cutters and buffing machines.

How can the risk be reduced?

Organisations must ensure that HAV risk tools and processes are identified, and carry out a risk assessment on their use.

The following measures should be considered:

i. Avoid the need to use vibrating tools in the first place. For example, by reviewing cleaning effects on floors, avoid the need to use buffing machines. Remember to consider ergonomic factors such as tool weight, handle design comfort, grip force needed, ease of handling and other risks such as noise and dust.

ii. Reduce the vibration generated by carefully selecting tools with lower vibration levels. Ask suppliers to provide information about vibration magnitudes that the products are likely to create in normal use. Consider purchasing the low-vibration designed equipment that is on the market.

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iii. Using anti-vibration dampers and mountings or vibration isolating handles may help reduce HAV.

iv. Instigate a proper maintenance programme for tools according to manufacturer's instructions. Replace vibration mounts before they wear out, keep tools sharp, ensure rotating parts are checked for balance and replace them if necessary. For example, sharpening chainsaw teeth and keeping the correct chain tension are important when using chainsaws. It may be possible to fit anti-vibration handles to tools retrospectively as long as the handle is matched to the vibration characteristics of the tool.

v. Reducing the period of exposure - consider job rotation and establishing safe work procedures by ensuring workers work for limited periods and then have a change in activity.

vi. Remember employees must receive information and on-the-job training and supervision to ensure they understand the risks and how to avoid or reduce them and to report signs of injury. They must be shown how to use tools to reduce excessive grip pressures, push and guiding forces. Equipment users must also be advised to use the lightest tool for the job and to rest the tool as much as possible on the material being worked or support provided, and to hold the tool with a light but safe grip. Provide information on maintenance of good blood circulation by keeping warm, warming up, exercising fingers and not smoking, as this adversely affects blood circulation.

vii. Ensure a list of all staff at risk is sent to the Occupational Health Service and request in writing that a health surveillance programme is carried out for HAV.

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1.7.3 Understanding Vibration Data

Note:-

you are not required to express any equations for HAVs. This is for information only.

Vibration magnitude.

Exposure to HAV is measured in terms of acceleration of the surface in contact with the hand as it moves one way and back again. This is normally expressed in m/s2. Particular frequencies, 5 - 20 Hertz (Hz, cycles per second of energy), will cause most damage.

Information from suppliers is often presented as vibration magnitude data. However, much of that data is derived from laboratory type conditions that may not be indicative of typical work conditions. Ask suppliers for data and information available for the types of work carried out in your area. They are obliged by law to help with such advice.

Daily vibration exposure.

The vibration exposure or dose of a worker depends on the duration they are exposed and it is standardised to a reference period of 8 hours, thereby allowing different exposures to be compared. It is currently recommended that preventative measures and health surveillance are provided when workers' daily vibration exposure regularly exceeds 2.8 m/s2 A(8).

It is possible to work out the daily exposure when the vibration magnitude of a tool is known.

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For example, information from a supplier of a chainsaw states that vibration magnitude is 9.7m/s2. The equipment is worked on for 2 hours per day.

Using A(8)= ahw√t/8

where t is the daily exposure time in hours.

A(8) = 9.7√2/8 = 4.8m/s2 A(8)

Where there are a number of different exposures, you can use the

formula:

A(8) = √ (A1(8)2 + A2(8)2 + A 3(8)2)

Where data is not available from suppliers, or there is concern that the data is insufficient, it is possible to measure individual exposures, but this should be carried out by an expert.

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1.7.4 Anti- Vibration GlovesGloves can be helpful in reducing risks from HAV. In cold conditions,

gloves will keep the hands warm, aiding circulation. Gloves are often necessary to protect against other risks.

Any gloves supplied must be able to be used with the tool and task. Ensure that the wearer finds them comfortable and is able to manipulate the tools properly without increasing grip or force.

Various gloves with special soft linings intended to reduce vibration risks are available commercially. These usually provide little attenuation at the most hazardous frequencies and - in some cases - may increase the vibration reaching the hand.

Therefore, unless test data are available for both the glove and the tool, it is best to assume they will not reduce the exposure to HAV.

The risk of HAV depends on what?

1.   ?   All of the above2.   ?   How tight your grip is3.   ?   How high the vibration levels are

4.   ?   How long the equipment is used for

How can the risk of HAV be reduced?

1.   ?   Avoid vibrating tools2.   ?   All of the above3.   ?   Select low vibrating tools

4.   ?   Use dampners and isolating handles

1.8 Welfare and Work Environment Issues36

Welfare and work environment issues are all covered within The Workplace (Health, Safety and Welfare) Regulations 1992; we will mainly be looking at the following areas:

supply of drinking water; washing facilities; sanitary conveniences; accommodation for clothing; rest and eating facilities; seating; ventilation; heating; lighting.

1.8.1 The Workplace (Health, Safety and Welfare) Regulations 1992

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Overview

The Welfare Regulations were made under Section 15 of the Health and Safety at Work Act and apply to virtually all workplaces - a notable exception being construction sites, although similar requirements are contained in the Construction (Health, Safety and Welfare) Regulations 1996, and farming and forestry land which is away from the main buildings.

Regulation 2 of the Welfare Regulations defines a "workplace" as "any premises or part of premises which are not domestic premises and are made available to any person as a place of work". This includes any place on the premises to which a person has access while at work. For example: rooms, lobbies, corridors, staircases, roads or other places used as a means of access or egress from a place of work or where facilities are provided for use in connection with the place of work other than a public road.

The requirements aim to ensure that workplaces meet the health and safety needs of each member of the workforce. Therefore, special consideration may need to be given to the needs of employees with disabilities.

For example, several of the regulations require things to be "suitable for any person in respect of whom such things are so done or provided". This emphasises, amongst other matters, that traffic routes, facilities and workstations which are used by persons with disabilities should be suitable for them to use.

Regulation 4 requires every employer to ensure that every workplace,

modification, extension or conversion which is under his or her control, and where any of the employees work, complies with the requirements of the Regulations.

Tenant employers are also responsible for ensuring that the workplace complies and that the required facilities are provided. Where facilities, such as sanitary conveniences and washing facilities, are provided by a landlord or a neighbouring business, the employer is still responsible for ensuring that they comply.

1.8.2 The Workplace (Health, Safety and Welfare) Regulations 1992 Continued.

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The following table provides a brief outline of the main requirements:

REGULATION SUBJECT OUTLINE

5 Maintenance

Workplaces, equipment, devices and systems to be maintained in:

o an efficient state;

o efficient working order;

o good repair.

Subject to a suitable system of maintenance where appropriate. Included in the above are those in which a fault is liable to cause a breach in the Regulations and mechanical ventilation systems provided under Regulation 6.

6 Ventilation Effective and suitable provision to ensure every workplace is ventilated by a sufficient quantity of fresh or purified air. There must be an effective device to give visible or audible warning of failure.

7 Temperature

Must be reasonable during working hours. Heating and cooling methods must not result in injurious or offensive fumes. A suitable number of thermometers must be provided for persons to determine the temperature in any workplace. According to the supporting ACoP, the temperature must be at least 16o

C unless work involves severe physical effort, when it should be at least 13oC.

8 Lighting

Suitable and sufficient lighting in every workplace, so far as is reasonably practicable by natural light. This must include emergency lighting in any room in which persons at work are especially exposed to danger in the event of failure of artificial lighting. Fire precautions legislation also concerns the lighting of escape routes.

9 Cleanliness Workplaces, furniture and fittings must be kept sufficiently clean. Surfaces of floors, walls, and ceilings must be capable of being kept sufficiently clean. Waste materials must not accumulate, except in suitable receptacles.

Persons must have sufficient floor area, height and

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10 Space unoccupied space. The ACoP suggests the total volume of the empty room divided by the number of people normally working in it, should be at least 11 cubic metres. (Any height above 3 metres should be taken as 3 metres. The 11 cubic metres per person may be insufficient where much of the room is taken up by furniture etc).

11 Workstations and Seating Must be arranged to be suitable for both the person and the work. (Special arrangements are required for outdoor workstations). A suitable seat must be provided where the work can or must be done seated.

12 Floors and Traffic Routes

Floors, where necessary, must have an effective means of drainage. They must be kept free from obstruction and substances which could cause slips, trips and falls.

Traffic routes must be constructed to be suitable for the purpose.

Floors and traffic routes must not have holes, slopes, uneven or slippery surfaces which expose persons to risk.

13

Falls

Suitable and effective measures to prevent any person from falling a distance likely to cause personal injury or being struck by a falling object likely to cause personal injury. The measures taken should not, so far as is reasonably practicable, involve personal protective equipment information, training or supervision. (Special arrangements required where falls into dangerous substances could occur.)

According to the ACoP, secure fencing should be provided, wherever possible, at any place where a person might fall 2 metres or more.

14 Windows, etc Every window and translucent surface in a wall, partition, door or gate shall, where necessary, be of safety material or be protected against breakages. It must also be appropriately marked or incorporate features to make it apparent.

15

Windows, Skylights and Ventilators

Must be capable of being opened. Must not be constructed in a manner which either exposes the person opening or closing them to risk or when open exposes any person to risk.

According to the ACoP, they should not project into an area where persons are likely to collide with them.

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16 Cleaning Windows Windows must be designed and constructed so as to be cleaned safely. According to the ACoP, where they cannot be cleaned safely from the ground then suitable provision shall be made for them to be cleaned. This may include using pivot windows which can be cleaned from the inside, fitting access equipment such as cradles or providing suitable conditions for future use of mobile access equipment (anchorage points for securing ladders etc).

17 Traffic Routes Workplaces must be organised to allow vehicles and pedestrians to circulate safely. Traffic routes must be sufficient in number, suitable for the person and vehicles using them, be in suitable positions and be of sufficient size.

18 Doors and Gates Must be of suitable construction. More detail is given in the Regulations in relation to specific types of doors and gates.

19 Escalators and Moving Walkways

They must function safely, be equipped with safety devices and be fitted with one or more emergency stop controls.

20 Sanitary Conveniences

Suitable and sufficient conveniences must be provided at readily accessible places. The rooms must be:

o adequately ventilated;

o adequately lit;

o kept clean.

Separate rooms needed for both sexes except where each convenience is in a separate room capable of being secured from the inside.

According to the ACoP, 1 WC is needed for the first 5 employees and another one for every 25 employees above that number. (Where only men are involved, another table gives the number of WCs and urinals to provide).

Suitable and sufficient facilities must be provided. Showers must be provided where required for health reasons. Facilities must be readily accessible and in the immediate vicinity of sanitary conveniences. The facilities provided must include:

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21 Washing Facilities

o A supply of clean hot and cold (or warm) water.

o Soap or other means of cleaning.

o Towels or other means of drying.

The rooms used must be adequately ventilated, adequately lit and kept clean. Separate facilities being provided for both sexes except in a room intended to be used by one person at a time and whose door can be secured from the inside.

The accompanying ACoP suggests that 1 washstation be provided for the first 5 employees and an additional 1 for every 25 employees above that figure.

22 Drinking Water An adequate supply of wholesome drinking water must be provided. Supplies must be readily accessible and conspicuously marked. Suitable cups or drinking vessels must be provided unless a drinking fountain is used.

23 Storage for Clothing Suitable and sufficient accommodation must be provided for non-working clothes and special clothing not taken home. Facilities must be included for drying clothes, so far as is reasonably practicable.

24 Changing Clothes Suitable changing facilities must be provided where necessary.

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Resting and Eating

Non-Smokers

Pregnant Women etc

Suitable and sufficient and readily accessible facilities must be provided for resting. Suitable facilities to eat must be provided where food eaten in the workplace would otherwise be likely to be contaminated. Suitable and sufficient facilities should be provided where meals are regularly eaten in the workplace.

Rest-rooms and rest areas must include suitable arrangements to protect non-smokers from discomfort caused by tobacco smoke.

Suitable facilities shall be provided for any person at work who is a pregnant women or nursing mother to rest.

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1.8.3 Further details - Supply of Drinking Water

An adequate supply of wholesome drinking water, with an upward drinking jet or suitable cups, should be provided.

Water should only be provided in refillable enclosed containers where it cannot be obtained directly from a mains supply.

The containers should be refilled at least daily (unless they are chilled water dispensers where the containers are returned to the supplier for refilling).

Bottled water/water dispensing systems may still be provided as a secondary source of drinking water.

1.8.4 Further Details - Sanitary Conveniences and Washing Facilities

Suitable and sufficient sanitary conveniences and washing facilities should be provided at readily accessible places.

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They, and the rooms containing them, should be kept clean and be adequately ventilated and lit.

Washing facilities should have running hot and cold or warm water, soap and clean towels or other means of cleaning or drying.

If required by the type of work, showers should also be provided.

Men and women should have separate facilities unless each facility is in a separate room with a lockable door and is for use by only one person at a time.

1.8.5 Further Details - Accommodation for Clothing

Adequate, suitable and secure space should be provided to store workers' own clothing and special clothing.

As far as is reasonably practicable, the facilities should allow for drying clothing.

Changing facilities should also be provided for workers who change into special work clothing.

The facilities should be readily accessible from workrooms and washing and eating facilities and should ensure the privacy of the user.

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1.8.6 Further Details - Rest and Eating Facilities

Suitable and sufficient, readily accessible rest facilities should be provided.

Rest areas or rooms should be large enough, and have sufficient seats with backrests and tables, for the number of workers likely to use them at any time.

They should include suitable facilities to eat meals where meals are regularly eaten in the workplace and where the food would otherwise be likely to become contaminated.

Seats should be provided for workers to use during breaks. These should be in a place where personal protective equipment need not be worn.

Work areas can be counted as rest areas and as eating facilities, provided they are adequately clean and there is a suitable surface on which to place food.

Where provided, eating facilities should include a facility for preparing or obtaining a hot drink. Where hot food cannot be obtained in - or reasonably near to - the workplace, workers may need to be provided with a means for heating their own food.

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Canteens or restaurants may be used as rest facilities, provided there is no obligation to purchase food.

Suitable rest facilities should be provided for pregnant women and nursing mothers. They should be near to sanitary facilities and, where necessary, include the facility to lie down.

Rest areas and rest rooms away from the workstation should include suitable arrangements to protect non-smokers from discomfort caused by tobacco smoke.

1.8.7 Further Details SeatingWorkstations should be suitable for the people using them and for the work.

People should be able to leave workstations swiftly in an emergency.

If work can - or must - be done sitting, seats which are suitable for the people using them and for the work done there should be provided. Seating should give adequate support for the lower back and footrests should be provided for workers who cannot place their feet flat on the floor.

1.8.8 Further Details VentilationWorkplaces need to be adequately ventilated. Fresh, clean air should be

drawn from a source outside the workplace, uncontaminated by discharges from flues, chimneys or other process outlets, and be circulated through the workrooms.

Ventilation should also remove and dilute warm, humid air and provide air movement which gives a sense of freshness without causing a draught. If the workplace contains process or heating equipment or other sources of dust,

46

fumes or vapours, more fresh air will be needed to provide adequate ventilation.

Windows or other openings may provide sufficient ventilation but, where necessary, mechanical ventilation systems should be provided and regularly maintained.

These regulations do not prevent the use of unflued heating systems designed and installed to be used without a conventional flue.

1.8.9 Further Details – Heating

The risk to the health of workers increases as conditions move further away from those generally accepted as comfortable.

Risk of heat stress arises for example, from working in high air temperatures, exposure to high thermal radiation or high levels of humidity, such as are found in foundries, glass works and laundries.

Cold stress may arise for example, from working in cold stores, food preparation areas and in the open air during winter.

Assessment of the risk to workers health from working in either a hot or cold environment needs to consider two sets of factors: personal, and environmental.

Personal factors include body activity, the amount and type of clothing, and duration of exposure.

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Environmental factors include ambient temperature and radiant heat and if the work is outside, sunlight, wind velocity and the presence of rain or snow.

Any assessment needs to consider:

Measures to control the workplace environment, in particular heat from any source. Minimising the risk of heat stress may mean insulating plant which acts as a source of radiant heat, using local cooling by increasing ventilation rates and maintaining the appropriate level of humidity. If it is not reasonably practicable to avoid workers being exposed to cold environments, you should consider using local environmental controls for example, cab heaters in fork-lift trucks used in cold stores.

Restriction of exposure by, for example, re-organising tasks to build in rest periods or other breaks from work. This will allow workers to rest in an area where the environment is comfortable and, if necessary, to replace bodily fluids to combat dehydration or cold. If work rates cause sweating, workers may need frequent rest pauses for changing into dry clothing.

Medical pre-selection of employees to ensure that they are fit to work in these environments.

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Use of suitable clothing (which may need to be heat resistant or insulating, depending on whether the risk is from heat or cold).

Acclimatisation of workers to the environment in which they work. Training in the precautions to be taken. Supervision, to ensure that the precautions identified by the assessment

are taken.

1.8.10 Further Details Lighting

Lighting should be sufficient to enable people to work and move about safely.

If necessary, local lighting should be provided at individual workstations and at places of particular risk such as crossing points on traffic routes.

Lighting and light fittings should not create any hazard.

Automatic emergency lighting, powered by an independent source, should be provided where sudden loss of light would create a risk.

Within the welfare regs? Adequate, suitable and secure space should be provided to store workers' own clothing and special clothing. As far as is reasonably practicable the facilities should allow for drying clothing.

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1.   ?   False

2.   ?   True

1.9 Noise

Noise can be simply defined as unwanted sound. The "unwanted" aspect of noise may be because of many reasons, such as damage to hearing or annoyance

.

1.9.1 The Effects on Hearing of Exposure to Noise

The danger here depends on how loud the noise is and how long you are exposed to it.

The damage builds up gradually and you may not notice changes from one day to another, but once the damage is done there is no cure. The effects may include:

sounds and speech may become muffled so that it is hard to tell similar sounding words apart, or to pick out a voice in a crowd;

permanent ringing in the ears (called tinnitus); a distorted sense of loudness - sufferers may ask people

to speak up, then complain that they are shouting; needing to turn up the television too loud, or finding it

hard to use the telephone.

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You should not have to suffer damage of this sort because of noise at work. It can be prevented by reducing noise levels, for example by fitting enclosures and silencers to machines, and using ear plugs or ear muffs properly if you have to work in noisy areas.

Hearing loss caused by exposure to noise at work continues to be a significant occupational disease. Recent research estimates that 170,000 people in the UK suffer deafness, tinnitus or other ear conditions as a result of exposure to excessive noise at work.

Work activities that create high levels of noise are subject to the Control of Noise at Work Regulations 2005. The Regulations place a duty on the employer to take necessary steps to reduce the noise levels produced to a level as low as is reasonably practicable (meaning weighed against the time, money and effort to correct the hazard).

Injury to a person's hearing can be induced temporarily by a sudden noise or over a period of time due to regular exposure. The degree of damage depends on a number of factors including overall intensity of noise, duration of exposure, frequency characteristics and individual susceptibility.

Early symptoms of damage due to noise exposure may be a temporary dullness of hearing. This may be accompanied by a ringing in the ears, called tinnitus.

Temporary elevation of the hearing threshold known as Temporary Threshold Shift (TTS) usually fades off gradually after exposure ceases. However, if exposure is repeated before recovery is complete, some degree of permanent damage may set in.

Hearing damage induced by exposure to noise over a prolonged period has been shown to result from damage/destruction of the hair cells of the Corti.

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As well as direct ill-health, effects from noise secondary hazards can also arise i.e. the noise could reduce the audibility of a warning sound or an alarm. In addition, noise can cause fatigue and cause physical and psychological stress that can affect moods, energy and concentration. These symptoms can reduce productivity and affect the quality of the work.

As a rule of thumb, the noise level is likely to be unacceptably high wherever a person has to shout to someone about 2 metres away. Prudent employers should be able to gain necessary data prior to the above rule, in order to ascertain the current noise levels.

However, under either of these circumstances the employer must make an assessment of noise exposure to the employees. These measurements must be compared to the legally defined levels. These are:

Below 80dB(A): No action after reducing the noise level as far as is reasonably practicable.

Between 80 dB(A) and 85dB(A): Hearing protection must be provided, the employee advised to wear them and information about the risks involved provided.

Above 85 dB(A): Hearing protection provided with enforced use, information given about the hazard, the area designated a hearing protection zone and signed accordingly.

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1.9.2 Factors in Noise Damage

The following factors all play a part in noise damage:

intensity; sound pressure; frequency ; the decibel scale and dB(A).

Intensity (loudness or level) results from the sound pressure of vibrations

The sound pressure is measured in A-weighted decibels (dBA). A-weighting adjusts for the human ear's varying sensitivity to different frequencies. The decibel scale is logarithmic, so every 3 dBA doubles the noise and every 10 dBA means a ten-fold increase: 90 dBA is 10 times louder than 80 dBA, and 100 dBA is 100 times louder. Speech is about 50 dBA.

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The noise level in factories averages 80-100 dBA. Jet engines run at about 130-140 dBA.

Source

Intensity

Level

Number of Times

Greater Than TOH

Threshold of Hearing (TOH) 0 dB 100

Rustling Leaves 10 dB 101

Whisper 20 dB 102

Normal Conversation 60 dB 106

Busy Street Traffic 70 dB 107

Vacuum Cleaner 80 dB 108

Large Orchestra 98 dB 109.8

Walkman at Maximum Level 100 dB 1010

Front Rows of Rock Concert 110 dB 1011

Threshold of Pain 130 dB 1013

Military Jet Takeoff 140 dB 1014

Instant Perforation of Eardrum 160 dB 1016

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Frequency.

The human ear can hear frequencies between 16 Hertz (Hz) and 20,000 Hz. Speech frequencies are 250-4000 Hz. High frequency sounds are more dangerous.

Duration.

Longer exposure increases the damage.

Nature.

Noise can be stable, fluctuating or intermittent. Impulsive noise (such as hammering) is particularly harmful.

Damage.

This begins at or before 80dBA. After exposure to 85dBA for 8 hours a day for 15 years, 5 per cent of workers will show hearing loss. The same length exposure to 90dBA will damage 14 per cent of workers and to 95 dBA, 24 per cent of workers.

According to the Control of Noise at Work 2005 mandatory ear protection zones must be in place where the Lepd is _____dB(A)

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1.9.3 Action Levels and Simple Noise Measurement Techniques

Although sound levels can be measured on the dB(A) scale, in practice noise is rarely steady or regularly fluctuating. Consequently, we require a method whereby we can assign some numerical value to a noise level which may vary considerably over a period of time.

Equivalent continuous sound level (Leq) is the notional steady level which would have emitted the same A weighted sound energy over the same time as the actual noise. In effect, the fluctuating instantaneous noise level is being averaged over a period of time. The concept is similar to the time-weighted averaging of airborne contaminant concentrations which we studied earlier.

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If we choose a nominal 8-hour working day for the time period, we establish an 8-hour equivalent continuous sound level. It is termed the daily personal noise exposure, abbreviated LEP,d, and is the measure of noise exposure required for comparison with the first action level of 80 dB(A) LEP,d; and the second action level of 85 dB(A) LEP,d

Noise Dose.

The damaging effects of noise are related to the total amount of energy or dose which the ear receives. The dose/energy depends on two factors: the level of noise and the duration of exposure.

It is commonly accepted that equal amounts of noise energy entering the ear cause the same deafness to exposed workers irrespective of the noise or exposure profiles.

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Thus a short exposure to a high level of noise is considered to cause comparable hearing damage to a long exposure to a low level of noise.

Criteria for noise exposure are based on this concept of equal energy damage risk. As noted earlier, the Noise at Work Regulations 2005 (Regulation 2) specify action levels for noise exposure at which the employer has to take specific action. The action levels are expressed as equivalent continuous daily personal noise exposure levels or LEP,d.

For example, exposure at the second action level is defined in the regulations as an equivalent continuous daily personal noise exposure level (LEP,d) of 85 dB(A). This is equivalent to exposure to a continuous noise, at an unvarying level of 85 dB(A), occurring for 8 hours. Exposures with different combinations of sound level and duration can also produce an LEP,d of 85 dB(A). This is illustrated in the following table:

Sound Level dB(A) Exposure Equivalent to 90 dB(A) LEP,d

85

88

91

94

97

8 hours

4 hours

2 hours

1 hour

30 mins

58

100

103

15 mins

7.5 mins

Each exposure represents a 100% permitted exposure at the second action level. Note that if the sound level is doubled (represented by a 3 dB(A) increase on the logarithmic scale), then the duration of exposure has to be halved for the total dose to remain the same. Also note how important it is for hearing protection to be worn continuously in high noise environments.

1.9.4 Exposure Levels

Personal noise exposure can be calculated from measurements obtained from a simple sound level meter when an individual works in a single location where the noise level is fairly constant.

Where the sound level is more variable or the workers movements are irregular, then determination of LEP,d becomes more complex.

Noise dosimeters provide a simple means of measuring LEP,d where workers are exposed to complex and variable noise fields.

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These small, personal monitoring devices are worn by employees through a representative part of the working day.A microphone picks up and integrates the noise level continuously so that at the end of the sampling time a direct reading of LEP,d is displayed.

Daily personal noise exposure is governed by three action levels:

The first action level establishes an LEP,d of 80dB(A).Above this level, there is potential for hearing damage and therefore the employer must make available suitable and efficient personal ear protectors for those who request them.

The second action level establishes an LEP,d of 85 dB(A).This is the exposure limit for noise and at this level, the employer must ensure that exposure is reduced to the lowest level reasonably practicable other than by the provision of ear protectors.Areas at this level of exposure must be designated as ear protection zones.

The third action level is a peak action level of 200 pascals (equivalent to 140 dB) and is likely to be linked with the use of cartridge-operated tools and similar loud explosive noises.This action level is important where workers are exposed to a small number of loud impulses during an otherwise quiet day.

Thus the requirement on the employer is to assess noise levels within the premises, establish the level of daily personal noise exposure and comply with relevant provisions of the appropriate action level.

In addition, and irrespective of action levels, there is an overriding duty on the employer to reduce the risk of damage to the hearing of employees from exposure to noise to the lowest level reasonably practicable.

The responsibilities are summarised in the table below:

Action is required where exposure is likely to be (see Note 2):

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Less than 80 dB(A)

80 dB(A) or more

85 dB(A) or more (See Note 1)

EMPLOYER'S DUTIES:

GENERAL DUTY to reduce risk of hearing damage to the lowest level reasonably practicable.

ASSESSMENT of noise exposure to be made by a competent person.

RECORD of assessments to be kept until a new one is made or employee leaves.

REDUCE daily exposure (other than by the use of ear protectors) so far as is reasonably practicable.

INFORMATION, INSTRUCTION AND TRAINING to be provided to employees about risks to hearing, their obligations, reducing the risk, and the use of ear protectors.

MARK ear protection zones with notices.

EAR PROTECTORS must be provided for all employees who ask for them.

They must be provided for all

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exposed.

They must be maintained and repaired.

Their use must be ensured.

They must be worn in marked zones.

EQUIPMENT must be properly maintained.

MANUFACTURER'S AND SUPPLIER'S DUTIES

Adequate INFORMATION on the noise likely to be generated must be supplied.

NOTES:(1)All the actions required at this level are also required where the peak sound pressure is at or above 200 Pa (140 dB).

(2)This requirement would apply to all who enter the zones, even if they might not stay long enough to receive an exposure of 85 dB(A).

1.9.5

Simple Noise Measurement TechniquesSound intensity is measured by a microphone which

converts the sound waves into

electrical impulses. These can be amplified and displayed electronically in suitable units.

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Duration, for continuous non-fluctuating noise levels measured with a sound level meter, can simply be estimated from the work pattern of the persons exposed.

For example, in the case of individuals working in a heavy engineering factory where there is a steady high background noise, duration will simply be the time spent in that location.

However, where noise levels are intermittent and variable, which is more often the case, duration is much more difficult to estimate. Under such circumstances we would use a noise dosimeter, which automatically registers the change in noise level with time and displays the information in a form easily converted to LEP,d.

Frequency variations are accommodated by the A weighting network built into the electronics of the noise meter. Consequently, the meter automatically displays the sound level in dB(A).

If the noise level meter is fitted with an octave wave band analyser, we can break the noise down into frequency bands and measure the intensity of each. Thus it is possible to establish which frequencies in the spectrum are the loudest, enabling us to assess their contribution to the overall noise level.

1.9.6 Use of a Sound Level Meter

Construction.

The picture below gives a generalised diagram of a sound level meter. In essence, the meter consists of three main parts:

Microphone assembly.

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Electronic measuring and amplification. Indicating meter.

Digital display instruments have a similar layout but are easier to use.

Sound Level Meter

A simplified schematic representation of the main operating sections is given below.

1.9.7 Basic Principles of Operation

The sound pressure from the air is converted into an identical electrical signal by a high quality microphone. The signal is changed from a high input impedance by the pre-amplifier.

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The signal strength from the microphone is very small, so it must be passed through an input amplifier to provide enough signal strength to eventually pass to the indicating meter.

After amplification, the signal passes through the section called a weighting or filtering network; this allows linear or weighting scale signals to be generated. After further amplification, the output signal is high enough to drive the indicating meter.

Between amplification and the meter, the sound signal, which will have an ac characteristic, is rectified to give the proportional dc output required by the meter.

Within the electronic structure of the measuring system, there will be refinements which allow attenuation of the sound signal to cover the wide 1012

or more sound intensities to be recorded.

The attenuation system allows measurements to take place above a certain dB level indicated. For high sound levels, the attenuator would be set only to record values above, for example, 90 dB, i.e. on the meter scale this would give a scale reading from 90 dB, through a scale of 30 dB, to 120dB.

If the sound level was below 90 dB, then the attenuation would be reduced to 80 dB to give a scale range of 80 dB to 110 dB. To prevent overload of the system, the meter should be set to high attenuation before use and then can be adjusted down if necessary.

You should note the scale calibration is in arbitrary dB units. The precise value recorded will depend upon the weighting system used, e.g. if

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linear measurements are made, the meter reading will be recorded as dB lin, or if A weighting is used, dB(A).

The response control is a method of damping out sound level variations which cause the meter needle to fluctuate too rapidly when a measurement is being made. In practice, a slow response setting is used for general noise level measurements.

On/off controls usually incorporate the battery check circuit. It is very important that the battery strength is sufficient to drive the operating parts of the meter; otherwise, meter readings will be worthless.

1.9.8 Use of Sound Level Meters

There are some basic general rules which can be followed when carrying out a simple noise level survey with a sound level meter.

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Setting up Sound Level Meters.

Check batteries for adequate output. Calibrate the meter using the appropriate calibration

attachment. Set the meter on slow response. Set the meter to read A weighted sound level. Set the meter to read the highest attenuation reading possible

(this is done to protect the meter from unknown high sound levels).

Before readings are taken, re-check batteries.

Schematic Representation of the Sound Level Meter.

1.9.9 Carrying Out Noise Survey

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Measurements should be taken with the process or equipment under operating conditions but without operators in position (thus preventing stray reflections).

Measurements should be taken at a height of about 1.5 m from the floor, where work is carried out in a standing position and about 1.2 m if operators are seated. The horizontal distance from the noise source should be about 1 m. The sound level meter must be held or supported at least 0.5 m from your body to prevent stray reflections from you.

Following the path given by the distances above, obtain readings at about 2 m intervals around the noise source.

Having identified general noise patterns, re-measure area with operators in position. Measure at points of highest noise, at the operator's ear and convenient intermediary positions.

Re-check batteries and calibration of sound level meter. Record results in dB(A) at appropriate positions on a plan of the

workplace.

1.9.10 Dosimeters

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Since we are concerned primarily with the noise dose received by a worker, the degree of auditory hazard to which a person is exposed is better estimated by monitoring the worker rather than the workplace.

If workers experience many different levels during their shift, their noise dose calculations can only be performed accurately by means of an instrument capable of measuring the Leq over the whole of the shift.

For workers who move about into various levels of noise exposure during their work, it is difficult to use a static integrating sound level meter. Personal noise dosimeters provide a convenient solution as they fit into a pocket and the readout is directly in percentage dose or Leq.

The microphone of the dosimeter can be attached from the brim of a safety helmet or to a lapel. It should be placed on the side of the operator likely to receive the most noise. Thus the microphone receives the same sound pressure as the wearer's ear, which the dosimeter A weights and totals over the measurement period to display as noise dose. Dosimeters vary in their exact method of operation, so it is difficult to generalise on the details of their use. However basic points to note are:

The equipment should be calibrated before use. As the instrument stores information over the period of

measurement it is important to ensure that all previous data has been erased from the memory.

Care should be taken in positioning the microphone to ensure a representative reading at the ear; also to safeguard against the microphone being knocked and registering artificially high readings.

After the period of exposure, the noise dose (LEP,d) can be calculated from the dosimeter reading. By using data from Table 7.2 a judgment of likely harmful effects or an estimate of permissible duration of exposure can be made.

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1.9.10.1 Video: Noise measurement

1.9.11

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Basic Noise Control Techniques

Reducing the risk of hearing damage and reducing noise exposure.

The Regulations do not prescribe precise methods of noise control but recognise that many approaches will be valid depending on the circumstances. Some methods that could be used in your workplace are discussed below.

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Control of noise at source - Vibration isolation.

Noise is generated by vibration of a surface or a fluid flow. Any modification of this vibration will modify the noise generated. The first stage, therefore, is to identify the vibrations that are causing the most significant contribution to the noise.

For instance, the stiffness of a vibrating surface can be modified if the structure is altered by bolting or welding ribs on the surface. The size of the surface can also be reduced or the surface can be isolated from the remaining structure.

Absorption.

These materials which are mainly porous in order to dissipate the sound energy are normally applied to surfaces to eliminate sound reflection and reduce reverberant noise build-up within an enclosed space. They are, for example, applied to the internal surfaces of equipment casings and noise enclosures for this purpose.

1.9.12

Basic Noise Control Techniques Continued72

Sound insulation

These materials, which form a sound barrier, are applied to attenuate the level of sound being transmitted through a panel, duct, wall or partition. It is their mass effect which provides the noise reduction and this can - in many cases - be further increased by the lamination to the material of a spacing layer, often a sound absorption material.

Damping

Typical applications

chutes; hoppers; machine guards; panels; conveyors; tanks.

1.9.13 Basic Noise Control Techniques Continued

Technique.

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There are two basic techniques:

unconstrained layer damping where a layer of bitumastic (or similar) high damping material is stuck to the surface;

constrained layer damping where a laminate is constructed.

Constrained layer damping is more rugged and generally more effective. Either re-manufacture steel (or aluminium) guards, panels or other components from commercially-available sound deadened steel or buy self-adhesive steel sheet.

The latter can simply be stuck on to existing components (inside or outside) covering about 80% of the flat surface area to give a 5 - 25 dB reduction in the noise radiated (use a thickness that is 40% to 100% of the thickness of the panel to be treated).

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Limitations: the efficiency falls off for thicker sheets. Above about 3mm sheet thickness, it becomes increasingly difficult to achieve a substantial noise reduction.

Silencers.

Where the noise is caused by turbulent air or liquid flow in

ductwork or at air exhausts or jets, these can be modified by reducing the velocity, fitting silencers, limiting pressures and flows to the minimum required. Doubling the air flow rate within a duct can increase the noise levels by up to 15 dB(A).

Aerodynamic noise can be generated by fans and air jets. The basic control technique here is to reduce the speed of the fan or the air jet causing the air turbulence which is the source of the noise. However, with simple fan noise it is often most economic to install a silencer.

Maintenance.

Fans, even in small equipment such as office printers, may

become dirty and so get out of balance and vibrate. Adequate lubrication is important because, apart from reducing wear, the wetting of surfaces in contact can reduce noise generation.

Mechanical handling equipment such as component sorting, counting, transport and packaging often involves repeated impact. The use of plastics or rubber

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New machinery.

When selecting new machinery, it is important to select those

that are least noisy. Ideally, this will have been a primary consideration at the planning and design stage. The purchaser should liaise with the supplier before installing any equipment and between them agree on appropriate noise specifications.

Controlling noise at source: checklist of techniques

Adequate and regular maintenance of machinery. Substitute a quieter machine or process. Isolate/coat vibrating parts. Apply coatings to vibrating panels. Use mufflers or silencers on noisy air jets.

1.9.14

Noise Control in the Open

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Enclosing the noise source is clearly the most effective means of

noise control in the open.

Screens or barriers can be used but their value is limited because noise does not travel in precisely straight lines, but tends to curve round obstacles.

The effectiveness of a screen depends on its height and length in relation to its distance from the source and its distance from the receiver. In general, a screen will be effective only if:

it is higher than the source and higher than the receiver; the source is close to the screen or the receiver is close to

the screen (or both for maximum benefit); its length is greater than its distance from the source or the

receiver (or both for maximum benefit).

The screen must be solid and continuous with no gaps or openings. A reflecting surface such as a high wall behind either the source or the receiver will reduce the effectiveness of the screen between them.

Where noise is caused by turbulent air or liquid flow in ductwork or at air exhausts or jets _____ can be an effective control measure.

1.   ?   Damping2.   ?   Sound insulation

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3.   ?   Absorption materials

4.   ?   Silencers

1.9.15 Control of the Noise Path

The next method of noise reduction to consider is to modify the

route which the noise must take to get from the source to the operator.

One of the problems with this approach is that unless the work is being carried out in the open, there will be a number of routes by which the noise reaches the operator.

If the operator is within two metres of the sound source then most of the noise is likely to be received directly. As the distance between the operator and the noise source increases, so does the importance of the indirect routes, e.g. noise reflected off the ceiling or from the wall behind the machine or any other hard surfaces.

This means that any point in the room will be subjected to direct noise reflected from the machine and indirect noise released off the other surfaces. This reflection of noise is known as "reverberation".

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If the room has hard, flat surfaces and no openings, the reverberant level will be nearly constant over the whole room.

Close to the machine, most of the energy travels by the direct path from the machine so the presence of the room's walls and ceiling makes little difference. Further away, the reflected paths are more important and the total noise level approximates to a constant reverberant level.

Inside a reverberant room, a screen is likely to be of little value because noise energy, in effect, just bounces back and forth until it gets round the screen. The only noise path interrupted is the direct path which carries only part of the total noise energy reaching the receiver.

If a machine is completely enclosed in a brick building or steel box, the noise level is increased inside the enclosure as a consequence of reverberation. This effectively reduces the noise- insulating value of the enclosure.

The most obvious way of modifying the route from the noise source to the operator, and normally the most cost-effective approach, is to enclose, or partly enclose, the machine with a suitable sound-absorbing material.

This has the effect of reducing the direct noise which is normally the most important component. The more complete the enclosure, the more effective will be the noise attenuation.

1.9.16 Simple Noise Barriers

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The background noise component of exposure can be modified by

using absorbent materials on the ceiling and walls of the building and therefore reduce the amount of the noise which is radiated back from these surfaces.

The effectiveness of this type of acoustic treatment will depend on a number of factors such as the reflectiveness of the existing surfaces, the importance of the background noise level in the overall noise, the frequencies of the noise produced and the size, shape and layout of the room.

This acoustic or absorptive treatment is only useful where reverberant noise is a problem as it does not control direct noise. It is generally useful in two types of situation:

1. In large work areas containing local noise sources. The noise level remote from the machines can be reduced considerably and local screens can also be used beneficially. This can apply in a workshop, a large office with office machinery at one end or a computer room where one part is required as a quiet work area.

2. In a large work area with many noisy machines distributed throughout, the total reverberant noise level may then be higher than the direct noise level at the operative's position beside each machine, so absorbent treatment is helpful.

1.9.17 Distance

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If machines cannot be silenced, then moving or re-sitting the

machinery so that it is further away from workers will help to reduce exposure levels.

Arrangements can be made for pipe work to be re-routed or for exhausts to be discharged well away from workstations.

Groups of noisy machines can be sited together or noisy processes segregated so that fewer people will be exposed to them, and the area can be designated as an ear protection zone.

By segregating the sources of noise, using protective equipment and setting up a job rotation scheme, exposure times can be significantly reduced. Introducing the use of remote controls can also have a beneficial effect.

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1.9.18 Basic Noise Control Techniques: Summary Checklist

For a noisy machine, the following steps could be carried out.

Check around the machine, making observations as to where the noise is generated and how the energy is radiated into the air.

Take measurements of sound pressure levels round the machine, close to surfaces and further away.

Is it possible to modify the noisy machine in some way? If this is impracticable, then it is generally necessary to employ one of the basic techniques of isolation, insulation or absorption.

1.10 The Purpose, Application and Limitations of Personal Hearing Protection

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Ear protection.

The use of hearing protection should be considered as a method of

last resort, or solely as an interim measure in protecting operators from noise.

When it is likely that exposure will be to the first action level or above in circumstances where the daily personal noise exposure is likely to be less than 85 dB(A), suitable and efficient personal ear protectors are available to those who request them.

For exposures at or above the second or peak action levels, suitable ear protectors must be provided which when properly worn can be reasonably expected to reduce risk of hearing damage to below that caused by an unprotected exposure at these levels.

There are various forms of hearing protection equipment available including ear plugs, ear muffs and helmets. Each form of protection has its own specific characteristics. However, all types should:

be comfortable and safe to use; be aesthetically acceptable; not provoke a toxic reaction in the wearer; not impair speech communication.

Ear protectors provided must comply with any relevant UK legislation and be compatible with other protective equipment worn simultaneously.

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1.10.1 The Purpose, Application and Limitations of Personal Hearing

Protection Continued

Ear plugs.

Ear plugs are made of soft pliable material

and fit in the ear canal. They may be separate or connected by a cord or neck band which can prevent loss.

They can be permanent, disposable or re-usable. Disposal ear plugs are probably the most commonly used and are generally made from plastic foam or glass wool covered in plastic.

Their main advantage is that they will fit most people. Permanent ear plugs are made from rubber or plastic and come in a range of sizes so that they fit the individual ear more tightly. It is possible to obtain custom-made plugs.

Where re-usable ear plugs are employed, the employer should have a system which ensures their regular cleaning and replacement. This may be important in hygiene-sensitive areas, such as food preparation.

Ear plugs are not suitable for all persons. If the user has experienced outer ear infection or irritation, care should be taken in their use and any medical opinion on suitability should be noted.

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Ear muffs.

Ear muffs usually consist of hard plastic cups that sit over the ears. A

soft seal containing plastic foam or a viscous liquid limits noise leakage through to the ears and the inner surfaces.

They are normally covered in noise-absorbing materials, again often soft plastic foam. Cotton covers can be used over the cup seals in particularly hot environments as an aid to comfort.

Various kinds of headband are used to hold the cups in place, the selection of which may depend on the situation in which the ear muffs will be used. A simple sprung plastic or steel band over the head is the simplest form which may be adjustable for pressure.

Unfortunately, this type is difficult to wear with a helmet of any kind. Soft bands that pass over the top of the head, using a pressure band behind the neck can be used with helmets, but these can be inconvenient to use if they need to be removed frequently.

Where head protection is necessary, it may be beneficial to use ear muffs directly attached to the helmet and many manufacturers produce this type. If spectacles of any type are worn at the same time, they may interfere with the cup seals.

While it would be simplest in most organisations to provide a single type of hearing protection for all staff in all areas in which they are needed, it can be seen that such a solution is not always possible.

Most organisations tend to offer a selection of suitable equipment for use in each area and leave it to the individual to choose which to use on the basis of comfort, etc. Even so, it is seldom necessary for a company to provide more than two specific types of ear plugs and two types of ear muff.

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The choice depends on circumstances of use and operator comfort e.g. ear muffs can be awkward to wear for a person having thick spectacle frames. Generally, ear muffs give better protection than ear plugs.

As part of the assessment, you should look at the level of protection given by the ear protection and if it will control the noise to an acceptable level for the operator - 80 dB as a maximum and as far below this as possible.

Under the new CE standards, all protective ear plugs and ear defenders must inform you of their Noise Attenuation, in other words, their ability to lower the sound level heard by the operator wearing the ear protection.

When you buy an item of ear protection, the manufacturer now gives details of the protection offered. This allows you to choose the ear protection to suit your circumstances of use.

1.10.2 Issue of PPE

Disposable and re-usable ear plugs need no special procedure for

their issue. They do have to be readily available, and instruction and training issues are as important as with the other forms of protection.

They are especially useful for visitors or those infrequently exposed to noise.

Any of the "permanent" types of plug should be fitted to individuals by someone trained in this process. Ear muffs do not need specialist fitting but a check on complete coverage of the ears and completeness of the seal should be made.

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1.10.3 Maintenance

Hearing protectors must be in good condition to provide the designed

noise reduction. Points that should be checked include:

the condition of ear muff seals: they can become torn, detached and liquid seals can become hard or leak;

tension of headbands whether there has been unauthorised modifications, such as holes drilled in ear muff cups, noise-absorbing material removed or personal stereo speakers fitted;

general condition, resilience and softness of ear plugs and cleanliness.

These simple checks can be carried out by the users after suitable instruction and the use of a set of new protectors for comparison is good practice.

Spare replaceable parts should be kept in stock and repair or replacement carried out when defects are discovered.

Cleaning should be carried out regularly and scrupulous attention must be paid to this with re-usable and permanent plugs. It is important to have clean hands when inserting plugs to prevent contamination of the outer ear canal during insertion. If ear muffs are to be re-issued to another person, they must first be carefully cleaned and sanitised.

Proper facilities for storage must be provided to keep ear protectors secure. For plugs, this could be a small plastic container in which they are often supplied; for ear muffs a locker or small individual container in a

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convenient location may need to be provided. Cleanliness of the storage facilities, e.g. the small plastic supply bags for ear plugs is also important in stopping infection.

1.10.4 Training

The training in use of protectors will depend on the types in use but

should include:

the correct method of ear plug insertion; importance of correctly fitting ear muffs, making sure

the seals fit all around and that no protection is lost through wearing spectacles or other intrusions;

the importance of cleanliness and methods of cleaning; the importance of use at all times during exposure to the

noise environment.

Records of training and subsequent issue of protectors should, as with all PPE, be kept.

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1.10.5 Ear Protection Zones

Any part of the premises where

employees are likely to be exposed to the second action level or above, or to the peak action level or above, must be

designated as an ear protection zone.

Signs should include text indicating that this is an ear protection zone and that personal ear protectors must be worn whilst in the zone.

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1.10.6 Audiometry

It is good practice to

encourage employees to have their hearing checked regularly, if they are exposed to significant levels of noise at work.

Audiometry is concerned with measuring the hearing sensitivity or acuity of an individual.

The use of audiometry enables a measurement to be made of the level of detection of noise by an individual at different frequencies. Considerable individual variation occurs, caused by factors such as age and disease.

Where hearing loss is noise-induced, the raising of the threshold of hearing occurs at about 4 kHz and gives a distinctive pattern to the audiogram.

Many employers do provide audiometry services for employees, though they are not a legislative requirement. Audiometric testing of employees acts as a backup test to ensure that the control of noise exposure is effective and may also provide early warning of noise-induced hearing loss, enabling an individual to be counselled and action to be taken to prevent further deterioration.

Not all noise-induced hearing loss is occupationally caused. Considerable evidence exists of damage to hearing being caused by leisure activities such as listening to loud music or DIY repairs and this can confound the results of an audiometry programme.

Also, audiometry can be used to detect conditions not induced by noise which may be treatable to the benefit of both employer and employee.

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The introduction of an audiometry program can, however, cause difficulty and should only be undertaken after careful consideration and with professional advice.

When employees are initially screened, it is likely that many individuals will be identified as having noise-induced hearing loss and this might lead to

compensation claims, although it is possible that the damage occurred during previous employment.

An ongoing audiometry program should, therefore, include pre-employment screening to establish a baseline against which any future results can be compared.

It is also a good idea to carry out audiometric tests when an employee is due to leave the present employer so that - should litigation occur - these records can show that any alleged hearing deterioration occurred after the period of employment and the final test.

1.10.7 Provision of InformationEvery employer must provide employees who are likely to be exposed to

the first or peak action levels or above with adequate information, instruction and training on:

the risk of hearing damage that exposure may cause; possible actions to reduce that risk; steps to be taken by employees in order to obtain personal ear

protection; employees' obligations.

For more information see the HSE Noise Site

Health and Safety Commission (HSC) published the formal Consultation Document on the Proposals for new Control of Noise at Work Regulations

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implementing the Physical Agents (Noise) Directive (2003/10/EC) on 5 April 2004 covering both draft Regulations and Guidance.

Physical & Psychological Health Hazards & Controls

Congratulations - end of lesson reached

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