Noise

Exposure to excessive noise in a workplace is a physical hazard . It is a serious and widespread problem in many New Brunswick workplaces. Exposure to excessive noise [>85dBA] can cause short term (acute or reversible) or permanent hearing loss (chronic or irreversible) depending on the type of noise the employee is exposed to. Different types of work generate different types of noise.

It's important to know that overexposure to noise doesn't necessarily take a long time. Short periods of very high noise can cause overexposure and irreversible damage to the ear. Other health hazards from noise can cause a number of physiological and psychological effects. These can include:

  • Interfering with speech, concentration and thought processes
  • Disrupting sleep
  • Fatigue and aggression
  • Reduced immune response

High level noise may initially cause dull hearing and ringing in the ears. Regular high level noise exposures will lead to hearing loss and other adverse health effects. Low level noise can interfere with activities or concentration and causes similar stress and health effects as high level noise.

The three main types of noise are distinguished by how the noise changes over time.

  • Continuous noise remains constant and stable over a period of time. For example, boilers in a powerhouse, fans, vibrating machines and compressors.
  • Variable or intermittent noise fluctuates between quiet and loud in a given time period. For example, woodworking machines and sewing machines.
  • Impulse or impact noise occurs in very high intensity and very short duration. For example, punch press, hammering and gun shots.

To prevent health hazards from excessive noise exposure, as an employer you must:

  • Measure the noise levels and the time spent by an employee when it is suspected the employee's exposure exceeds 80 dBA .
  • Consult with the joint health and safety committee or health and safety representative, if any, or with employees on the types of hearing protective equipment to be used.
  • Make reports available to the joint health and safety committee or representative and to an officer on request.
  • Ensure the exposure to noise does not exceed sound level and time limits, including but not limited to:
    • More than 85 dBA for 8 hours,
    • More than 88 dBA for 4 hours, or
    • More than 91 dBA for 2 hours. See regulation 91-191 for other exposure limits
  • When using a sound level meter to measure noise, use calculations to determine an employee's noise exposure when the employee is exposed to substantially different levels of sound during a work day.
  • Take every reasonable precaution to protect employees from exposure to hazardous sound levels, and ensure no employee's time-weighted average (TWA ) exposure exceeds 85 dBA.
  • When practical, install and use appropriate engineering controls to control the noise at the source and provide hearing protective equipment to keep the exposure to noise within the allowable limits if engineering controls cannot be used to limit exposures.
  • Ensure any hearing protective equipment conforms to CSA standard Z94.2-94 “Hearing Protectors ” or an equivalent standard for hearing protection.
  • Where noise levels exceed 85dBA ensure that the area is clearly marked by a sign that indicates the range of the noise levels measured and warns of the noise hazard.

As an employee, you must:

  • Wear hearing protection, when required by the employer if you are exposed to noise levels such as:
    • More than 85 dBA for 8 hours
    • More than 88 dBA for 4 hours
    • More than 91 dBA for 2 hours
  • Know how to fit, use and care for hearing protectors.

To determine employee TWA (time-weighted average) exposure, an audio (or noise) dosimeter or a sound level meter can be used. It is important to note the differences, including advantages and disadvantages between both pieces of equipment. CSA has developed a standard that can be used as a guide to properly measure employee exposure to noise (CAN/CSA-Z107.56-06, "Measurement of Occupational Noise Exposure ").

Dosimeter
Sound meter

Interpretations/Details

The two main types of hearing protection are muffs and plugs . They each have advantages and disadvantages but generally ear muffs provide better protection. (Reference: WorkSafeNB – Hearing Protection)

Plugs and muffs should have a Noise Reduction Rating (NRR) printed on the packaging. This is the protection provided in an ideal situation. In the real world, the protection may only be half of the printed NRR and this needs to be considered when determining if employees are adequately protected when working in noisy environments.

Hearing Conservation Program

While not currently required by regulation, a hearing conservation program with all its elements, including audiometric testing and training, is necessary when employees are exposed to noise at or above the TLVs® to ensure that the control measures are effective.

General Regulation - Occupational Health and Safety Act
N.B. Reg. 91-191

Part V NOISE AND VIBRATION

Section 29

29. (1) Where an employer or an employee has reason to suspect that the noise level in an area where employees work may exceed 80 dBA, an employer shall ensure that

(a) the noise level is measured by a competent person using a sound level meter that conforms as a minimum to the requirements of ANSI standard S1.4-1983, "American National Standard Specification for Sound Level Meters", for a Type 2 sound level meter that is set to use the A-weighted network with slow meter response, and

(b) the amount of time that an employee spends in an area where the noise level exceeds 80 dBA is measured.

(2) An employer shall ensure that the information obtained under subsection (1) is documented and made available to a joint health and safety committee or health and safety representative, if any, and to an officer on request.

(3) Where there is reason to suspect that substantial changes in noise levels documented under subsection (1) have occurred, an employer shall ensure that the noise level and employee exposure is re-measured and documented in accordance with the requirements of subsection (1).

Section 30

30. (1) An employer shall ensure that the exposure of an employee to noise is kept as low as is practical and does not exceed the following exposures:

Table

Sound level Duration per day
dBA Hours
80 24
82 16
85 8
88 4
91 2
94 1
97 1/2
100 1/4

(2) An employer shall ensure that when the daily noise exposure is composed of periods of noise exposure at substantially different levels, their combined effect is considered, rather than the individual effect of each, according to the following formula:

If the sum of the following fractions:

Equation

exceeds unity, then the mixed exposure is considered to exceed the relevant exposure prescribed in subsection (1). C1 indicates the total duration of exposure at a specific noise level, and T1 indicates the total duration of exposure permitted at that level. All job noise exposures of 80 dBA or greater shall be used in the above calculations.

(3) An employer shall ensure that no employee is exposed to continuous, intermittent or impact noise in excess of a peak C-weighted level of 140 dB, using a Type 2 sound level meter that is set to use the A-weighted network with slow meter response.

[N.B. Reg. 2001-33, s. 12]

Section 31

31. Where the installation of engineering controls is practical, an employer shall install and use appropriate engineering controls to comply with section 30.

Section 33

33. Where the noise level exceeds 85 dBA in an area, an employer shall ensure that the area is clearly marked by a sign that indicates the range of the noise levels measured and warns of the noise hazard.

Part VII PROTECTIVE EQUIPMENT

Section 48 Hearing Protective Equipment

48. (1) An employer shall ensure that hearing protective equipment conforms to CSA standard Z94.2-94, "Hearing Protectors" or a standard offering equivalent protection.

(2) An employer shall consult with a joint health and safety committee or health and safety representative, if any, or with employees if there is no committee or representative, concerning the selection of the types of hearing protective equipment to be used by employees.

(3) Where hearing protective equipment is required, an employer and an employee who uses the equipment shall each ensure that the equipment is kept in a sanitary condition.

[N.B. Reg. 2001-33, s. 21]