3. Regulation: Guideline: Amendments to Noise Requirements In the Regulation for Industrial Establishments and Oil and Gas-Offshore

• ISBN: 978-1-4249-4249-7
• Issued: May 2007
• Content last reviewed: June 2009

Noise Exposure Limits

Protective Measures

Warning Signs

The amended Regulations (Regulation respecting Industrial Establishments  and Regulation for Oil and Gas Offshore) contain three key requirements, which may be summarised as follows:

1. Employers are to take all measures reasonably necessary in the circumstances to  protect workers from exposure to hazardous sound levels that result in the L_ex,8 exposure limit of 85 dBA being exceeded (8-hour time-weighted average exposure)
2. When the exposure limit prescribed by the regulations is exceeded, the employer is required to put in place measures to reduce workers’ exposure. Protective measures may include:  engineering controls to reduce noise at the source or along the path of transmission; work practices such as equipment maintenance (to keep it quieter), or scheduling to limit a worker’s exposure time; and, personal protective equipment in the form of hearing protection devices, subject to the restrictions stated in the regulations
3. Employers must post clearly visible warning signs at the approaches to areas where the sound level regularly exceeds 85 dBA

The following sections quote provisions of the regulations in italics, and provide guidance beneath each excerpt.

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Noise Exposure Limits

"Every employer shall ensure that no worker is exposed to a sound level greater than an equivalent sound exposure level of 85 dBA, L_ex,8."

What limits apply?

The only applicable exposure limit is the 85 dBA, L_ex,8.

A worker's exposure to noise levels generally varies throughout the day. An 85 dBA L_ex,8 may be thought of as the permissible time-weighted average noise exposure that is averaged over an 8 hour shift.

This is similar in concept to the Time-Weighted Average Exposure Value (TWAEV) for a chemical substance in the Regulation respecting Control of Exposure to Biological or Chemical Agents (Regulation 833).

Note that by using appropriate instrumentation, impulsive or impact noise is automatically included in the measurements used to determine L_ex,8 exposure levels.

Appendix A discusses measurement equipment, selection, and use limitations.

There is no "ceiling" exposure limit for continuous noise and no maximum "peak" noise criterion. These are considered unnecessary, owing to the nature of the 85 dBA, L_ex,8 exposure limit. The National Institute for Occupational Safety and Health (NIOSH) has stated that a maximum or "ceiling" exposure limit for continuous type noise is considered unnecessary with an 85 dBA criterion level and a 3 dB exchange rate, both of which are inherent in the 85 dBA, L_ex,8 exposure limit. Similarly, a 140 dBC maximum "peak" noise criterion is unnecessary because exposure to such a sound level would result in the 85 dBA L_ex,8 exposure limit being exceeded in a fraction of a second.

How are noise exposures assessed?

Although the definition of equivalent sound exposure level in the regulations includes the formula set out in subsection (2), it is not anticipated that this equation will be widely used to determine Lex,8. The sound level or Leq measurement(s) used to determine an Lex,8 exposure level can be made using a noise dosimeter, an integrating sound level meter, or in some circumstances, a basic sound level meter. The Canadian Standards Association (CSA) provides guidance on equipment selection and specifications and on procedures for the measurement or calculation of Leq and Lex,8 in CSA Standard Z107.56-06 Procedures for the Measurement of Occupational Noise Exposure. View CSA Standards.

Compliance with Ontario’s regulatory requirements respecting noise exposure control does not necessarily mean that a comprehensive noise survey needs to be done in every workplace. Many employers will have previous sound level or dosimetry data that may be useful in assessing worker exposures and the likelihood of them exceeding the occupational exposure limit. Exposure data for a group of workers with the highest noise exposures may be useful to infer compliance for less exposed groups.

Even in the absence of such data, a crude assessment may be possible based on the ease or difficulty of speech communication at a normal conversation distance of about one meter. If it is necessary to speak very loudly, the sound level probably exceeds 85 dBA. This concept has been expanded upon by Malchairein the article Strategy for Prevention and Control of the Risks Due to Noise.

However, it would be appropriate for an employer to carry out a noise exposure survey using more sophisticated measurement tools if area sound levels are high enough to require speaking very loudly to communicate and action has not been taken to reduce them. Other indicators that a noise exposure survey is needed include use of equipment known to produce sound levels above 80 dBA in published data, worker complaints regarding noise and symptoms, or audiometric test results showing early signs of noise induced hearing loss.

Employers may contact their Safe Workplace Association or consultants specializing in noise assessments to assist them with assessing Lex,8 in their workplace, if they do not possess the required instrumentation, resources, or knowledge to carry these out where required. Also, the Occupational Health Clinics for Ontario Workers has published a useful Noise Calculator spreadsheet (Excel document).

See Appendix A for more detailed information about noise measurement equipment and Appendix B regarding the determination of L_ex,8.

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Protective Measures

"Every employer shall take all measures reasonably necessary in the circumstances to protect workers from exposure to hazardous sound levels."

This requirement is intended to protect workers from exposure to sound levels that would result in noise exposure above the 85 dBA, L_ex,8 exposure limit. This does not mean that protection is required only where area sound levels exceed 85 dBA. For example, a 12-hour exposure to 84 dBA would mean that worker protection is mandated, because the L_ex,8 exposure limit would be exceeded.

"Any measurement of sound levels in the workplace that is done in order to determine what  protective measures are appropriate shall be done without regards to any use of personal protective equipment."

All sound level measurements conducted for purposes of assessing noise exposures must be conducted without regards to the attenuation factor / safety factor provided by personal protective equipment (i.e. hearing protection devices--HPD ) being worn by the workers. Exposures are calculated assuming that workers are unprotected by HPDs.

"The protective measures shall include the provision and use of engineering controls, work practices and, subject to subsection (described below), personal protective equipment."

Similar to an occupational exposure limit for a hazardous chemical substance, when a worker is exposed to a daily noise dose exceeding the limit of 85 dBA L_ex,8, the employer must take measures to reduce the exposure to noise.   Measures may include engineering controls to reduce noise at the source or along the path of transmission, work practices (i.e. administrative controls such as limiting a worker’s exposure time, maintaining equipment), or personal protective equipment (i.e. hearing protection devices) subject to the restrictions below.

This requires the employer to consider all three types of controls to protect workers against noise, but does not necessarily expect the employer to use all three types for every situation.

As an example of work practices, also referred to as administrative controls, worker assignments in a noisy area could be rotated to limit the total shift exposure of each worker to an acceptable level. The benefits of this approach are somewhat limited, because the daily exposure of a worker has to be cut in half to reduce the L_ex,8 exposure by 3 dBA.

A more effective administrative control is a good preventive maintenance program to prevent equipment from becoming significant sources of noise. Also, developing and implementing maximum noise specifications for the purchase of new equipment is worthwhile, because it is usually cheaper to include noise controls at the design stage than to retrofit controls on existing equipment. CSA Standard Z107.58, Noise Emission Declarations for Machinery, provides guidance for specifying equipment using internationally recognised standards and procedures. View CSA Standards.

Engineering controls along the path of transmission generally mean introducing enclosures, partial enclosures, or barriers. These can be structures that enclose a piece of noisy equipment or enclose a work station in a noisy area.

There are many types of engineering controls at the source. The selection of which ones to apply in a given instance requires an assessment of the cause of the noise at that source. Some examples are: installing mufflers on air exhausts; purchasing quiet air jet nozzles; applying mechanical damping treatment to metal panels in impact situations; using vibration isolators on vibrating equipment; redesigning noisy saw blades or press dies; installing absorbent panels on building surfaces near noisy tools; and substitution of quieter machines, tools or processes, such as hydraulic rather than pneumatic power.

See Appendix C for more detailed information regarding noise controls

There are various resources available online discussing control measures:

• NIOSH has published an extensive Noise Control Manual
• CCOHS offers an inexpensive document titled Noise Control in Industry: A Basic Guide
• NPC offers the U.S. Department of Labour, Occupational Safety and Health Administration guide Noise Control--A Guide for Workers and Employees.

Employers may contact their Safe Workplace Association or consultants specializing in the design and fabrication of such noise controls. Most noise control equipment is available commercially. Acoustical consultants with experience in industrial settings can often provide effective solutions for specific noise sources or for reducing noise exposures generally in a facility.

"The employer shall protect workers from exposure to a sound level greater than the limit without requiring them to use and wear personal protective equipment."

The preferred and most effective way to control noise exposure is through engineering controls at the source or along the path of transmission. In keeping with good health and safety practice, hearing protection devices (HPDs) should always be considered as a last resort.

Engineering and administrative controls are preferable to HPDs because these devices are often less protective than their ratings, due to such factors as improper selection, poor fit, deterioration, user discomfort, and lack of user motivation.

"Workers shall wear and use personal protective equipment appropriate in the circumstances to protect them from exposure to a sound level greater than the limit" only if "engineering controls, 

1. are not in existence or are not obtainable;
2. are not reasonable or not practical to adopt, install or provide because of the duration or frequency of the exposures or because of the nature of the process, operation or work;
3. are rendered ineffective because of temporary breakdown of such controls; or
4. are ineffective to prevent, control or limit exposure because of an emergency. "

This subsection reinforces that personal protective equipment should only be used as a control measure as a last resort, and further qualifies when it can be relied on for worker protection. It should be noted, however, that nothing in the regulations precludes use of HPDs for noise exposures below 85 dBA and such use is considered advisable for exposures to sound levels above 80 dBA

The phrase "not reasonable or not practical to adopt, install or provide" is intended to allow use of hearing protection devices where an evaluation of other control measures indicates they are not practical or reasonable based on their effectiveness, cost, technical feasibility or implications for equipment use, service and maintenance.

To demonstrate compliance with this requirement, an employer should document what other measures have been considered and why those measures are not adopted, since they may be asked to provide such information.

For situations where employers rely on HPDs to protect workers against excessive noise exposures, the employer must ensure that the HPDs are appropriate and effective for the purpose. This means that employers are expected to develop and have a hearing protection program that includes training on the proper selection, use, and care of HPDs. Both CSA (in CSA Standard Z94.2-02 Hearing Protection Devices--Performance, Selection, Care, and Use ) and the National Institute for Occupational Safety and Health (NIOSH) have additional guidance in this regard. View CSA Standards.

While it is always important to control sound levels and worker exposure to noise before relying upon hearing protection devices and to select HPDs that are appropriate for the circumstances, HPD selection is even more critical in extreme noise environments. Sound levels in excess of 105 dBA may be considered extreme noise environments. Where it is not reasonable or practical to reduce the sound levels below 105 dBA and minimize worker exposure durations, special HPDs or dual protection from ear plugs and ear muffs may be necessary.

When selecting HPDs, it is often incorrectly assumed that the Noise Reduction Rating (NRR) on the package accurately predicts the dBA reduction that the device will provide. This is untrue for two reasons: 

First, the NRR is designed for use with C-weighted sound measurements, so if only A-weighted data are available there must be an adjustment to account for the difference between A-weighting and C-weighting.

Second, the data used to determine the NRR for a device are normally obtained under laboratory conditions, so devices must be "derated" to account for the significantly reduced protection provided under "real world" conditions.

Employers who use the NRR method to select hearing protection devices need to consider both of these factors when discussing the purchase of appropriate HPDs for their specific workplace noise environment.   

NIOSH addresses correct use of NRR taking both of these factors into account.

Also, see Appendix D for further discussion of HPD selection.

Although not required by the regulations, it is considered good health and safety practice for an employer, in consultation with the Joint Health and Safety Committee (JHSC), to implement a hearing conservation program that includes audiometric testing of workers regularly working in areas with noise levels exceeding 80 dBA. This benefits both workers and employers by identifying potential gaps in the noise exposure control program.

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Warning Signs

"A clearly visible warning sign shall be posted at every approach to an area in the workplace where the sound level measured as described, regularly exceeds 85 dBA."

The purpose of the signage requirement is to advise anyone, even non-workers, that they are entering an area that is, or may become, loud enough to cause damage to their hearing if unprotected, depending on the length of time they spend in the area. This requirement is intended to support a fundamental principal of the Internal Responsibility System (IRS), which is the worker’s right to know.

The intent of this section is for the employer to post a sign at every approach to an area where continuous or intermittent noise levels regularly exceed 85 dBA due to work that is normally conducted in that area. This would include intermittent noise from power tools, or equipment normally used in the area, but would exclude noisy one-time or rare activities that are not part of the regular activities in the area. However, if an area routinely exceeds 85 dBA, either continuously or intermittently, (i.e. press operation, pneumatic or electric grinder use), a sign or signs must be posted.

What must the sign indicate?

It is ultimately left to each employer to decide on what kind of warning the sign should provide, but it is recommended that the sign advise workers that there is a potential for hearing loss in that area, if unprotected, and what measures are to be taken to control this potential exposure.

The content of the signs may include, but is not limited to:

• Identification of actual sound level in dBA
• Warning of hazardous sound levels
• Requirement for mandatory  hearing protection in the area
• Providing the allowable exposure duration for this area, without hearing protection
• Icons indicating that hearing protection is to be worn
• Other form of controls required

Words on the signs may be in whatever language is appropriate for the workplace, but will normally be in English and the majority language of the workplace.

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