OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 16 Noise

Section 217 Noise control design

The most effective method of dealing with noise at a workplace is to prevent or eliminate the noise from being produced in the first place. The purpose of this section is to ensure that employers consider noise reduction up front when constructing or modifying a work site or work area, when introducing a new work process or introducing equipment that is new to the work site or work area.

Considering noise control in the design, construction or alteration of a workplace can create a more effective control system that takes into account factors such as work area orientation and the types of equipment to be used. Retrofitting a work site or work area with soundproofing or using other noise control strategies often results in less effective noise reduction. This is because the strategies must fit the existing work area – they may not be the optimal design for reducing noise to the desired level.

The material used in the construction of buildings, machines, piping and tanks has a direct effect on noise control. Some materials and structures dampen sound extremely well. Others do not and should be avoided if noisy equipment or processes will be present in the work area.

The construction or design of a new work site or significant physical alterations, renovations or repairs to an existing work site or work area must achieve a noise level of no more than 85 dBA, or as low as reasonably practicable. In determining whether noise has been reduced to the lowest level reasonably practicable, the employer needs to take into account:

(a) the orientation and size of the work area;
(b) the number and location of workers in the work area;
(c) physical parameters such as temperature, pressure and humidity;
(d) the types of building materials and construction techniques available to reduce noise levels;
(e) the type of equipment that will be used in the work area; and
(f) cost constraints.

The employer should document the assessment process, particularly if conditions at the work site are likely to change in the future.

Employers and workers need to stop buying new noise problems. Equipment or processes that involve high speeds, high pressure and high flow velocities, combined with light building structures and minimum floor space, can lead to noise problems if noise limits are not specified. Employers should target noisy equipment or operations for noise reduction through replacement, set noise level criteria for new equipment in purchase documents and request noise level specifications from manufacturers. Workers should be members of the purchasing team since they will be directly affected by the new equipment.

It is not just the noise that the equipment or process itself generates, but how much noise it will make once installed or introduced at the work site. Factors to consider include the total energy of the sound sources, how sound travels at the workplace, the ability of the room or area to absorb sound, and the degree to which the noise is concentrated in a certain direction as opposed to sound that radiates evenly in all directions.

The employer is required to ensure that new equipment is designed, constructed and installed to achieve the lowest noise level practicable. In some cases, it may be practicable to modify the equipment or substitute less noisy equipment. In other cases, the ability to control noise will be limited by

(a) technological constraints – some equipment is inherently noisy and advances in technology are unable to reduce its noise below a certain level;
(b) the availability of equipment or materials – there may be no alternative;
(c) space constraints – quieter equipment may be too large to fit into the available space;
(d) workplace conditions such as temperature, pressure, humidity, etc.; and
(e) cost constraints.

In these cases, other methods of noise control will be required to reduce worker exposure.