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Noise and Vibration [Nov 2011]

Published: 10th Nov 2011

Noise and vibration are among the most common hazards to be found in the workplace. Often underestimated in terms of the permanent and devastating effects they can have on the health and wellbeing of workers, such as permanent deafness and damage to nerves, muscles and joints, both noise and vibration need to be measured, monitored and adequately controlled.

Noise is vibration from machines or plant travelling through the air and reaching the listener’s ears - it is unwanted sound. Construction, manufacturing, mining, quarrying, drilling and engineering are some of the industries where the risk of noise damage to the human ear and to physical structures and equipment can be extremely high.

Vibration may be defined as the oscillatory motion of an object between two points and is sometimes treated as the ‘poor relation’ of noise because it commands less attention. There are two main types of vibration affecting people - hand-arm vibration (HAV) and whole-body vibration (WBV).

Hand-arm vibration is vibration transmitted from work processes into workers' hands and arms. It can be caused by operating hand-held power tools such as drills, saws and breakers, and hand-guided equipment, such as planers and sanders, or by holding materials being processed by machines. Industries where exposure to HAV is particularly high include construction, oil and gas, and heavy engineering, many of which are found in Middle Eastern countries.

Whole-body vibration is transmitted through the seat of vehicles or feet of employees who drive mobile machines such as tractors, lorries and forklift trucks or other work vehicles, and comes from machines or vehicles producing elevated vibration levels that shake the entire body.

Where vibration and noise occur

Vibration at work can occur during the use of any hand-held vibrating power tools - angle-grinders, jigsaws, chain saws, hammer drills or torque wrenches can all cause vibration - and the driving or operation of heavy machinery or vehicles that produce high vibration levels.

Excessive noise can arise during the use of loud equipment and machinery, or it can be produced if equipment is poorly maintained. Badly designed workplaces and the use of headsets turned up too high are other situations where noise? may be harmful. Noise at work can also cause other problems to workers, such as disturbance and interference with communications, as well as stress, distraction, difficulties with concentration, fatigue, tension and irritability.

Monitoring noise and vibration

Often, noise and vibration in the workplace go hand in hand - where there is too much vibration, there is too much noise, and vice versa.

Vibration is similar to noise in that it consists of the movement of particles, and, in many ways, noise and vibration could be said to be different aspects of the same thing. In vibration, however, the movement of particles occurs at a frequency below the range of human hearing. Vibration has distinct characteristics in different directions, making it essential to measure on each of its three axes independently, and preferably simultaneously.

Studies, such as those from the Institution of Mechanical Engineers and others, have shown that the ill effects of both vibration and noise combined can be much more intense than those of either vibration or noise alone. This fact makes powerful instruments that are able to measure and analyse both sound and vibration in one monitor very useful in occupational health, safety and environmental monitoring.

A study where the combined effects of vibration and noise on sweating of the palm were examined in healthy subjects in Japan showed that simultaneous vibration and noise caused a greater increase in palm sweating than occurred when each of the factors was in place separately.1 This has implications for operators of vibratory tools, who are exposed to both vibration and noise and whose hands and/or hearing are affected by the combined exposure.

Noise and vibration legislation - employers’ duties

The legislation in the UK, USA and Europe on noise and vibration is often considered the ‘gold standard’ to be followed in the Middle East, since there are few local regulations in the area. All Middle Eastern countries use ISO international standards and European and American standards.

In the UK, the Control of Vibration at Work Regulations 2005, which implement the European Physical Agents (Vibration) Directive 2002/44/EC, seek to protect workers from the harmful effects of vibration by placing a duty of care on employers to minimise the risks to their health, reducing exposure to vibration to as low a level as is reasonably practicable.

The Control of Vibrations Regulations specify daily exposure levels at which employers will be required to take action to control risks. These are known as Exposure Action Values (EAVs). The regulations also set out Exposure Limit Values (ELVs). Where these are reached, the employer must, by law, prevent further daily exposure.

Employers must also provide information and training on the risks to workers’ health and the actions they are taking to control these risks, and carry out health checks where risks are present.

All new machinery built in, or imported into Europe has to comply with the Machinery Directive 2006/42/EC, which contains more precise requirements concerning noise and vibration than the previous version of the Directive. Suppliers must provide information on the vibration emission value of their equipment.

Similarly, the Control of Noise at Work Regulations 2005, which implement the European Physical Agents (Noise) Directive 2003/10/EC, also aim to protect workers from the harmful effects of noise by placing a duty of care on employers to minimise the risks to their health.

In effect, the regulations say that the risk from noise and vibration must be identified, assessed and controlled in accordance with specific daily limits.

Employers must make personal hearing protectors available upon request to any employee who is exposed to noise at or above a lower EAV (80dBA). ISO Standards used in the Middle East for vibration are:

• Hand Arm: ISO 5349-1:2001 Mechanical vibration - Measurement and evaluation of human exposure to hand-transmitted vibration

• Whole body: ISO 13090-1:1998 Mechanical vibration and shock - Guidance on safety aspects of tests and experiments with people. Part 1: Exposure to whole body mechanical vibration and repeated shock

• Instrumentation: ISO 8041:2005 Human response to vibration - Measuring instrumentation specifies the performance specifications and tolerance limits for instruments designed to measure vibration values, for the purpose of assessing human response to vibration. It includes requirements for pattern evaluation, periodic verification and in-situ checks, and the specification of vibration calibrators for in-situ checks

The standard mainly used in the Middle East for noise is:

• ISO 9612:2009: Acoustics - Determination of occupational noise exposure

How noise is measured

The intensity of noise is measured in decibels (dB) for average or peak noise values at work. In the UK, the best practice exposure level is 85 dB for all workers averaged over an eight hour period. Prolonged exposure above this level will almost certainly result in hearing loss, which can also occur without long term exposure.

When measuring noise at work, emphasis is normally given to the frequencies or pitch of the sound, describing the rate of fluctuation of air particles produced by a noise source that has most effect on the human ear by adjusting the noise meter to take more notice of these frequencies. The scale used is called a ‘weighted decibel scale’ or dB(A).

The lower EAVs are a daily personal noise exposure of 80 dB and a peak sound pressure of 135 dB. The upper EAVs are a daily personal noise exposure of 85 dB and a peak sound pressure of 137 dB. The ELVs are a daily personal noise exposure of 87 dB and a peak sound pressure of 140 dB.

To put this into context, according to the Health and Safety Executive (HSE), some examples of typical noise levels are:

• Normal conversation 50–60 dB(A)

• A loud radio 65–75 dB(A)

• A heavy lorry about seven metres away 95–100 dB(A)

• A jet aircraft taking off 25 metres away 140 dB(A)

While the first two clearly are not hazardous, the second two examples do pose a hazard to hearing, since they exceed ELVs.

A small increase in the decibel scale corresponds to a large increase in intensity - the amount of sound energy being transmitted to the ear by vibrating air particles. For example:

• If the sound level increases by 10dB then the sound intensity increases tenfold

• An increase of 3dB corresponds to a doubling of intensity. Although 83dB sounds as though it is just over 80dB, it is in fact twice as intense, and so is potentially much more damaging to hearing.

Noise is measured by sound level meters - hand-held instruments for the measurement of employees’ noise exposure - and dosimeters, personally-worn sound exposure meters, are used to measure the noise exposure of an individual over the course of a working day and often used by mobile workforces.

How vibration is measured

Vibration exposure is measured in terms of acceleration, using units of acceleration that can be converted into ‘trigger-time’ to allow the worker to calculate how long a tool can safely be used for and calculate its ELV.

The daily exposure to vibration is measured by a formula known as an A(8) value. This is the average (A) exposure over an eight hour (8) day and takes into account the magnitude of the vibration and how long the worker is exposed to it. The rate of vibration of a tool or piece of machinery is measured in metres (m) per second (s) - its movement per second.

For hand-arm vibration, the daily ELV is 5 m/s2 A(8) and the daily EAV is 2.5 m/s2 A(8). For whole body vibration, the daily ELV is 1.15 m/s2 A(8) and the daily EAV is 0.5 m/s2 A(8). People will suffer if these levels are exceeded.

Before vibration can be monitored and measured, an initial risk assessment of the vibratory equipment should be done. Once this is completed, controls, information and training can be put in place.

Factors to take into account when measuring vibration after the manufacturer's data have been determined include:

• The length of time the vibrating tool is used (trigger time)

• The identification of operations that make up an exposure pattern

• The measurement of vibration for each operation

• The typical exposure time for each operation

Meters can then be used to measure the increasing amount of vibration from power tools. These meters alert the user to stop using the tools when they are approaching maximum exposure levels.

Dangers of excessive noise

One of the greatest dangers of too much noise in the workplace is temporary or permanent hearing damage. 170,000 people in the UK alone suffer deafness, tinnitus (ringing or buzzing in the ears) or other ear conditions as a result of exposure to excessive noise at work and so are less able to perform their jobs properly, if at all, opening themselves up to possible financial losses.

Noise is also a source of nuisance: it affects health and wellbeing and can cause damage to buildings, structures and equipment. Noise can be a safety hazard, because it can interfere with verbal communication, produce stress and affect workers’ performance.

Dangers of excessive vibration

Regular and frequent exposure to excessively vibrating tools can cause lasting injury. Vibration can be the cause of hand-arm vibration syndrome (HAVS), a very painful, permanent condition that does long term irrevocable damage to hands, fingers and arms including vibration white finger, where fingers turn white and numb. It can cause damage to nerves, muscles and joints in the body and whole-body vibration can lead to debilitating back pain.

Vibration, like noise, can also be a source of nuisance, affecting health and wellbeing and causing damage to buildings, physical structures and equipment.

Dangers of not monitoring

By not taking monitoring action how will your organisation be affected by vibration and/or noise?

If an organisation ignores the risk of vibration and noise and does not take steps to monitor and measure it, it lays itself open to many serious adverse effects. These include:

• Potential industrial or compensation claims, prosecutions, heavy fines and costs

• Adverse publicity

• Loss of productivity and profit

Inability to identify those at risk and so compile accurate and comprehensive statistics

Affect on employees

If vibration is not monitored, how will employees be affected by it?

Emplyees have an even greater potential than companies to be affected by vibration. They may suffer:

• Ill health, pain and distress, limiting of tasks, inability to do fine work or everyday tasks properly

• Reduced ability to work outdoors in cold or damp conditions

• Reduced grip strength affecting the ability to work safely

• Potential musculoskeletal, neurological, and vascular effects on the hand or arm such as carpal tunnel syndrome, causing pain, distress and sleep disturbance

Risk of permanent damage with sustained usage of vibrating tools

Influences on the impact of vibration on a worker include amplitude, magnitude, direction, duration and frequency of vibration.

If noise is not monitored, how will employees be affected by it?

Employees may suffer ill health, pain and distress from unmonitored and uncontrolled noise. Effects may include:

• Limited ability to undertake a range of tasks

• Inability to do everyday tasks properly

• Serious potential temporary or permanent hearing damage may occur

Benefits of monitoring and managing

There is a huge range of benefits to both the business and its employees if noise and vibration are monitored and controlled in the workplace. These include:

• Reduction of costs

• Protection of employees, improvement of health and safety and prevention of new cases of HAV syndrome and deafness

• The duration and extent of exposure can be limited

• New or alternative working methods and/or equipment and workplace layouts can be sourced that eliminate or reduce exposure to vibration and noise

• Employees are involved in managing their own health and safety risks, which is good for employee engagement and retention

• Training for employees can be facilitated

• There will be a consequent improvement in productivity and quality of work

• Increased plant/machinery uptime

• Extended machine life and reduced maintenance costs

• Significant financial benefits in complying with legislation, dealing with claims, reducing management time, reducing operating costs and lowering the cost of insurance.

Safety engineers, health and safety managers, plant, facilities and purchasing managers cannot afford to ignore or underrate the importance of noise and vibration in the workplace. The hazards of doing so, and the benefits of monitoring, measuring and controlling them speak for themselves. ?

Further Information

• Health & Safety Executive: www.hse.gov.uk/vibration/ and www.hse.gov.uk/noise/index.htm

• ISO Standards: www.iso.org

References

European Journal of Applied Physiology and Occupational Physiology

Author

Paul Rubens is Director of Sales and Marketing at Svantek UK, a joint venture between Svantek, of Warsaw, Poland and Acsoft, of Aylesbury, UK.

Paul has extensive experience in the health, safety and environmental technology marketplaces across Europe, Asia and the Americas, and spent more than ten years as Managing Director of one of the world's most successful health, safety and environmental monitoring instrumentation companies.

Paul specialises in helping businesses grow into exciting new areas. He has a proven track record in helping European-based businesses expand internationally and American and Asian businesses grow within Europe.

Paul also has wide ranging experience of working with the UK government, having led an environmental trade mission for UK trade and investment to Taiwan in 2007 and the first of a new series of trade missions to China initiated by the Prime Minister in 2008. He also chaired an international working group for the Environmental Industry Commission (EIC). In 2006, Paul was a guest at Buckingham Palace at a reception for members of the UK scientific community.

T: +44 7815 087905 E: paulrubens@svantek.co.uk

About Svantek

Svantek is a world leading designer and manufacturer of professional instruments for sound and vibration measurement and analysis. Established in Poland in 1990, the company boasts one of the best qualified and most innovative teams of design engineers in the market, employing three PhD and 15 MSc qualified engineers. Its range of noise and vibration monitors is second to none, with both quality and technical excellence being at the core of the company’s philosophy.

The company’s goal is to manufacture the highest quality products with the best price-versus-performance ratio in the world market. It numbers among its customers blue-chip companies such as Boeing, Bayer, Fiat, Hyundai, Renault, Samsung and Volvo. The company has representatives all over the world. www.svantek.co.uk

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Published: 10th Nov 2011 in Health and Safety Middle East

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