Occupational noise exposure

Excessive noise or unwanted sound in the workplace is annoying and can affect worker performance, as well as safety. To keep noise from stifling your company’s productivity and causing your workers discomfort, and perhaps injury, it is important to maintain an effective noise hazard assessment program. This involves assessing the workplace for noise hazards, taking appropriate measures to eliminate or control noise, and protecting workers from any such hazards that are found.

How noise works

Noise is a by-product of many industrial processes and exposure to high levels of noise can cause hearing loss. It can also cause stress on other parts of the body, resulting in increased muscle tension, a quickened pulse rate, and increased blood pressure. Workers exposed to excessive noise sometimes experience nervousness, sleeplessness, and extreme fatigue, all of which can affect productivity, quality, and safety.

Evaluating noise in your workplace

OSHA’s occupational noise standard at 1910.95 requires companies to provide protection against the effects of noise exposure when the noise levels exceed an 8-hour time-weighted (TWA) average of 90 decibels (dB). In order to determine if your company falls into this category, you need to evaluate noise in your workplace.

To begin a noise evaluation, you should consider these four points:

Noise level in each work area,
Equipment and processes that are generating noise,
Which employees/job functions are exposed to noise, and
Length of noise exposure (check production records.)

Monitoring: a critical part of evaluating noise exposure

To fully evaluate noise exposure in any facility, it may be necessary to monitor noise exposure levels. OSHA requires noise levels be monitored “when information indicates that any employee’s exposure may equal or exceed an 8-hour time-weighted average of 85 decibels.” Note: This 85-dB level also triggers OSHA’s requirements to have a hearing conservation program in place. (See 1910.95 (c)-(o))

The exposure measurement must include all continuous, intermittent, and impulsive noise within an 80 dB(A) to 130 dB(A) range and must be taken during a typical work situation.

A preliminary plant-wide noise assessment survey is a good way to locate operations or areas where workers may be exposed to hazardous noise levels. Problem areas warranting additional monitoring include those where it is difficult to communicate in normal tones and where workers have difficulty hearing, or have ringing in their ears after several hours of exposure.

Consider the source of the sound (as a distinct piece of equipment) and the ambient-noise level throughout the facility (a combination of equipment and/or systems) when measuring noise levels at each work station that an employee would occupy during the work shift.

Monitoring should be repeated when changes in production, process, or controls increase noise exposure. Such changes may mean that additional employees need to be monitored, and/or their hearing protectors may no longer provide adequate attenuation. Affected employees are entitled to observe monitoring procedures, and they must be notified of the results of the exposure monitoring.

The importance of engineering and administrative controls

Once you become aware of a noise problem in your workplace—usually meaning employee exposure levels exceeding an 8-hour TWA of 90 dB, you must next decide how to combat the problem. Engineering and administrative controls are essential to putting up an effective fight against workplace noise. According to the National Institute for Occupational Health and Safety (NIOSH) publication, “A Practical Guide to Preventing Hearing Loss,” engineering and administrative controls represent the first two levels in the hierarchy of controls: (1) remove the hazard, and (2) remove the worker. The use of these controls should reduce hazardous exposure to the point where the risk to hearing is eliminated or at least more manageable.

According to NIOSH, engineering controls are technologically feasible for most noise sources, but their economic feasibility must be determined on a case-by-case basis. In some instances, the application of a relatively simple noise control solution reduces the hazard to the extent that other elements, such as audiometric testing and the use of hearing protection devices are no longer necessary. In other cases, the noise reduction process may be more complex and must be accomplished in stages over a period of time. Even so, with each reduction of a few decibels, the hazard to hearing is reduced and communication is improved. Noise-related annoyance is also reduced, which could boost worker productivity as the workplace will be more comfortable.

Typical engineering controls involve:

Reducing noise at the source,
Interrupting the noise path,
Reducing reverberation, and
Reducing structure-borne vibration.

Administrative controls, defined as changes in the work schedule or operations that reduce noise exposure, may also be used effectively. Examples of administrative controls include operating a noisy machine on the second or third shift when fewer people are exposed, or shifting an employee to a less noisy job once a hazardous daily noise dose has been reached. Generally, administrative controls have limited use in industry because shifting from one job to another is often not possible due to worker skill levels or employee contracts. Moreover, NIOSH says that the practice of rotating employees between quite and noisy jobs may reduce the risk of substantial hearing loss in a few workers, but it may actually increase the risk of small hearing loss in many workers.

A more practical administrative control is to provide quiet areas, such as lunch rooms and break rooms, where employee can gain relief from workplace noise.

Providing hearing protection devices

Hearing protection devices (HPDs) are another weapon that can be used against workplace noise. HPDs refer to devices such as earmuffs, earplugs, and ear canal caps that can be worn to reduce the level of sound entering the ear. If your noise assessment shows that workers are exposed to excessive noise, and your company is unable to reduce the noise to acceptable levels using engineering and administrative changes, you must provide hearing protection.

For more information on hearing protection, see the Hearing Protection ezExplanation.

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