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Safety Focus: Limiting exposure to high levels of noise in industrial environments

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So far in this series, Ferret.com.au has discussed equipment used to safely access stock at height, as well as some measures that can be taken to minimise the exposure of mine workers to oxygen-deficient atmospheres.

Another key safety concern in industrial environments, and possibly one of the most prominent and noticeable, is exposure to high levels of noise. In an occupational setting, 'noise' refers to unwanted or damaging sound.

WorkSafe Victoria notes that exposure to high levels of noise can cause permanent hearing loss and tinnitus (ringing in the ears). There are two mechanisms by which this can occur.

First, continual exposure to loud noise over a period of time can eventually kill the nerve receptors in the inner ear. Once damage occurs to these sensitive receptors, it cannot be repaired.

A secondary, though probably more immediately concerning, cause of hearing loss is exposure to sudden loud noises, such as explosions or heavy hammering. WorkSafe explains that these types of noises are commonly referred to as 'impact' noises. If loud enough, noises of this kind can cause immediate, permanent hearing damage.

According to the National Standard for Occupational Noise, the standard for exposure to noise in the occupational environment is an average daily exposure level of 85 decibels, which "is consistent with overwhelming scientific evidence which indicates that exposure levels above 85 decibels represent an unacceptable risk to the hearing of those exposed."

Importantly, this standard refers to noise measured at the employee's ear. In addition, the effect of hearing protectors must not be taken into account in determining employees' exposure to noise.

There is a chance that the exposure standard may be exceeded if:
  • it is difficult to hear someone speaking to you from one metre away
  • employees notice a temporary hearing loss or ringing in the ears after leaving work; or
  • employees need to use hearing protectors.
WorkSafe advises that if an employer is unsure whether the standard is being exceeded, a determination must be made as to the level of noise employees are exposed to.

In simple cases this can be achieved by taking spot noise measurements using a noise sampler.

However, in more complex situations (particularly those situations where there are multiple sources of noise), a noise specialist may need to be called in to conduct an occupational noise assessment.

WorkSafe offers a number of potential solutions for industrial environments where excessive noise levels have been identified. Briefly, WorkSafe recommends that employers look at:
  • eliminating the cause of the noise
  • substituting quieter plants or processes, or use engineering measures
  • using administrative controls; and then
  • providing hearing protectors.
Eliminating the cause of the noise is straightforward, and simply entails the removal of excessively noisy equipment or processes. Obviously, though, this may not be possible in many industrial environments. In this case, substituting machinery and processes or using engineering measures may be appropriate.

An example of substitution would be employing a quieter compressor, or welding instead of riveting in large scale construction.

Engineering controls refer to measures such as:
  • erecting enclosures around machines to reduce the amount of noise emitted into the workplace or environment
  • using barriers and screens to block the direct path of sound; or
  • using absorptive materials to minimise noise reflection within the building.
Engineering controls can assist to:
  • avoid metal-on-metal impacts
  • reduce vibration
  • isolate vibrating machinery; and
  • silence air exhausts and blowing nozzles.
Where equipment or processes cannot be changed, attempting to change the way work is done through administrative controls may be an option. Noise sources, for example, might be positioned further away from employees, or the number of employees working in noisy areas could be reduced.

If the above measures have been applied as far as practicable, and they do not totally solve a noise problem, then WorkSafe states that hearing protectors must be used to ensure that employees' exposure to noise does not exceed the standard.

It is important to review risk controls regularly to ensure they are implemented correctly and to monitor their effectiveness. Risk controls should also be reviewed, and revised where needed, whenever changes are made to a workplace that could affect noise levels.

A review is also necessary if there is a report of hearing loss in the workplace, or if a health and safety representative requests one.

Employees and Health and Safety Representatives must be consulted when reviewing risk controls.

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