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Managing noise

The effective management of health and safety risks is an essential part of a good health and safety management system. When risk management is integrated into the core business functions, real change and improvement can be seen not only by preventing physical harm to the workers, but also by improving business performance.

Organisations and line managers have a responsibility to protect all workers from the harmful effects of noise generated in their workplace. This includes all workers whether employed on a temporary, permanent, or casual basis, as well as all visitors and contractors who may enter a noise zone in the workplace.

Due to the potentially high-risk nature of noise, organisations are required to control noise at the source and eliminate or reduce the risks where possible. Using the hierarchy of control is important to ensure the exposures are reduced to as low a level as possible. Based on the 3dB trading effect just a 3dB reduction in noise levels will half the impact the noise has on workers. Personal hearing protection should not be used as the only source of protection as noise can cause damage through the transfer of noise through vibrations which are transferred via the skull bone to the cochlear.

To manage health and safety risks effectively, organisations and workers need to fully understand them. Therefore, having a clear understanding of the noise-related risks and how these may affect individuals is crucial.

To establish and maintain a safe working environment, organisations need to ensure that:

  • noise surveys are conducted to quantify the noise in the workplace and set boundaries for limits using noise zones
  • workers needs are considered during the planning and organising of work
  • adequate controls are in place to eliminate or reduce workers exposure
  • noisy areas are clearly defined and separated, and enough safety signs are displayed
  • hearing protection is provided, maintained, and used correctly
  • workers are adequately instructed and trained
  • a regular health surveillance programme is in place (audiometry screening tests)
  • effective enforcement of controls is applied to mitigate exposure.

Workers need to know how to work safely and without risks to their health. Organisations must provide them with clear instructions and adequate training. The information must include:

  • the nature of risk and where it is located (risk assessment outcomes)
  • safe working practice/rules
  • the effects of noise on hearing
  • the purpose of hearing protection
  • instructions on fitting, use and care of hearing protection
  • the purpose of health surveillance, including audiometry testing
  • reporting problems as soon as they are apparent
  • workers within the organisation should be aware of what they are expected to do. When organisations provide information and training, they should assess the workers knowledge to ensure that training is relevant and effective. The information and training provided to workers should be in a form that is easy to understand.

Identifying the risks

Identifying noise as a potential risk can be as challenging as other health related risks, as they are often dealt with in a reactive way. However, organisations should be thinking proactively about identifying potential noise risks within the workplace.

The organisation will need to assess the levels of noise to which the workers are exposed. Results of the risk assessment must be recorded and kept up to date. When carrying out a noise risk assessment, the organisation must include the level (dB and Hz), type (continuous, intermittent, impact), and the duration of noise exposure in the various areas of the workplace. These should then be compared to legally established exposure limits and actions limits. The assessment will also need to include any interactions with other risks such as chemicals or vibrations.

The organisation must ensure that noise at work doesn’t exceed the established exposure limits. Where noise does exceed these limits, the organisation must implement/apply measures to eliminate or reduce the exposure to acceptable limits using the hierarchy of control.

Individual factors

Exposure to excessive noise is not the only hazard that can result in hearing impairment in the workplace. Certain chemical agents are ototoxic, for example, trichloroethylene, carbon monoxide, toluene, and medications such as some antibiotics, aspirin in large doses and loop diuretics are known to have a more than synergistic effect on the damage to hearing. Exposure to such chemicals may increase the impact of noise on hearing loss.

Other risk factors which may affect hearing could include:

  • aging, degeneration of inner ear structures over time
  • hereditary, the genetic makeup may make people more susceptible to ear damage from sound or deterioration from ageing
  • recreational noise, hobbies, or activities outside of work may also cause hearing problems, for example motorcycling, carpentry or listening to loud music
  • some illnesses, diseases or illnesses that might result in high fever such as meningitis, may damage the cochlea.

It’s important to take into consideration a worker’s hearing impairment they may already have. If their ability to undertake a safety critical task is compromised, this could pose a significant risk to their safety and others around them. The requirement for an assessment of fitness for safety critical task will only be applied when it is necessary and not used as a form of medical selection and potential discrimination.

It’s important to remember that the length of time of exposure is also important, noise levels at 85dB(A) may take as long as 8 hours to cause hearing damage whereas 100dB(A) may start damaging hair cells in the ears much quicker.

Controlling the risks

Once the risk of noise has been assessed, the next step is to control the risks.

The hierarchy of control is used to determine practical and effective risk control methods for the workplace based on the noise levels reported in the noise survey. The hierarchy of noise control includes elimination or substitution of noise sources, collective control measures through engineering and work organisation, and personal protective equipment (PPE).

There are several ways in which noise can be controlled, which will vary from one workplace to another. There’s no single technique or solution that is appropriate for every situation. A good understanding of the nature of the noise, its source, plant operations and work processes, as well as working hours are necessary to determine the most effective method of eliminating, minimising, or controlling the noise.

Factors the organisation should consider include:

  • the scale of the noise problem and its impact on the business (including workers)
  • cost and effectiveness of planned control measures
  • the number of individuals who would benefit from proposed control measures.

An essential outcome of noise risk assessment is identifying and prioritising measures to control the risks. Managers should use the risk assessment findings to formalist an action plan for controlling noise. The key actions will include:

  • prioritising immediate and high-risk areas identified in the noise survey
  • identifying possible methods to reduce noise
  • assessing the reduction levels that can be achieved by introducing cumulative controls
  • assigning responsibilities for implantation of controls
  • communicating the plan to all workers
  • monitoring controls and performance.

Elimination

Elimination is a process that removes the noise at the source and is the most effective way to prevent harm to workers. It is not always achievable, but examples would include eliminating impacts between hard objects or surfaces or moving and isolating the noisy operations away from other work activities.

Planning and introducing a suitable purchasing or hire policy are essential to reducing the level of nose at work. Considering at an early stage how the new work process or new machinery would work without exposing the workers to excessive noise is the most cost effective and long-term measure business can take to reduce overall noise levels. Before acquiring new machinery, its noise levels should be considered this can be achieved by liaising with and obtaining information from the manufacturer or supplier of the plant or machinery. This may include installation instructions, maintenance arrangements and likely noise levels under the specific conditions in which the machinery will be operated. Note: the noise levels should always be considered when introducing a new work process, selecting new work equipment, and designing the layout of the workstations.

Substitution

Substitution is a process of replacing noisy machinery or equipment with quieter alternatives. When elimination is not possible, substitution of the noisy machinery or equipment for quieter ones may be the next- best alternative to control noise.

Organisations should always consider alternative equipment and work processes which would make the job less noisy.

Performing a task differently can protect the workers as lower noise levels are generated for example, the use of hydraulic processes to bend material products produces less noise than hammering.

A risk assessment must be conducted to ensure the substitution of work processes does not introduce another type of risk, as seen when welding is introduced in place of riveting.

Table 1 shows some examples of substitution methods which can be adopted to reduce the level of noise in a workplace.

Noise source/process Alternative source/process
fuel engines electrical engines
pneumatic tools electrical tools
throwing positioning gently
solid wheels rubber tyres
metal gears
plastic gears
metal bearings fibre bearings
metal chutes and containers rubber or plastic chutes and containers
forging pressing
hammering gluing
stapling clipping
chipping grinding
rollers conveyor belts

 

Engineering controls

Engineering controls are all about making changes to processes, machinery, or equipment so that the workers are exposed to less noise. For example, using screens, barriers, enclosures, and absorbent materials that help to reduce workers’ noise exposure.

Some engineering measures that may be considered are:

  • separating the noisy area from other workspaces (eg sound proof control rooms)
  • enclosure of noisy machinery (boxing it in or placing in an enclosed space)
  • avoiding metal-to-metal contact by using plastic bumpers
  • using absorbent material on surfaces to cushion the fall or impact of objects on walls, ceilings, and floors to reduce the noise due to reverberation
  • using conveyor belts rather than rollers
  • using acoustical silencers/mufflers on intake and exhaust systems
  • using rubber mounts to isolate vibrating noise source to separate it from the surface its mounted to
  • maintaining optimum speed of machinery or its components
  • repairing and replacing loose rotating parts, worn bearings and gears
  • undertaking regular maintenance on equipment (very effective in reducing noise emission if carried out regularly)
  • increasing the distance between the source of noise and the workers.
Acoustic insulation material
 

Administrative controls

Administrative controls are the way work is organised to reduce either the number of workers who are exposed or the length of time they are exposed to noise. Administrative controls should be used when it is not possible to reduce noise exposure through elimination, substitution, or engineering control measures.

Some administration controls include:

  • identifying hearing protection zones and clearly sign-posting noisy areas
  • increasing the distance between noise sources and workers, the further away the noise source is, the less harmful its effect on workers will be
  • organising schedules so that noisy tasks are performed when as few people as possible are present
  • minimising the number of individuals working in a noisy area keeping individuals out of the area if their job does not require them to be there
  • limiting the time workers spend in a noisy area by job design and job rotation
  • providing rest breaks in areas away from a noisy work environment
  • providing sufficient information, instructions, and training to the workers for the proper use of work equipment
  • health surveillance to monitor effects of noise on hearing.

Personal protective equipment

Personal protective equipment (PPE) or in this case, hearing protective equipment (HPV) protects the users from any adverse effects on hearing caused by exposure to high levels of noise by providing a barrier between the noise and the pathway of hearing. It is the last option in the hierarchy of control and should be used as a last resort after all the efforts to eliminate or reduced noise levels have been exhausted through technical and organisational means.

All hearing protection must be capable of reducing the noise exposure to safe exposure levels, while allowing for communication to be heard without removing the HPE and should be made available at no charge for workers to use. It is important to ensure that the HPE chosen to protect the workers is suitable for the individual’s working environment and compatible with other PPE being used, for example hard hats, dust masks, eye protection etc. It is good practice to offer different types of protectors so that workers can chose ones which suit them better. This will improve compliance for the use of HPE.

It is important to consider a worker’s personal preference and health when selecting HPE. For example, workers who have hearing loss might not like to wear HPE because it makes communication more difficult. In these cases, meet with the worker and find the best option that will work for them. These workers need to understand that the continued uncontrolled exposure to noise they will continue to lose hearing until they are considered deaf.

Hearing protection comes with a single number rating (SNR) in the EU and a noise reduction rating (NNR) in the USA. This number in decibels provides an estimate of noise reduction provided to the user when wearing them. A basic earmuff will give the wearer an approximate protection of 22 to 33 dB reduction and basic foam ear plugs will give approximate protection of 20 to 30 dB reduction.

There will be circumstances where the SNR levels are not enough to reduce the loudness of the noise to a safe level. In this case, check other control methods to limit the time workers are exposed. However, this can be difficult for mobile workers or those workers who move around in the work environment e.g. maintenance crew. For more advice on protecting these workers, contact industry specific specialist consultants or organisations who will provide further guidance and information around how to control and manage exposure in the specific environments.

Hearing protection will only provide protection if worn correctly. Providing training to workers on how and when to wear HPE should be followed by an assessment of their understanding, to ensure it is effective.