Occupational noise is the amount of acoustic energy received by an employee's auditory system when they are working in the industry. Occupational noise, or industrial noise, is often a term used in

occupational safety and health Occupational safety and health (OSH), also commonly referred to as occupational health and safety (OHS), occupational health, or occupational safety, is a multidisciplinary field concerned with the safety, health, and welfare of people at wo ...

, as sustained exposure can cause permanent hearing damage. Occupational noise is considered an occupational hazard traditionally linked to loud industries such as ship-building,

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the econom ...

, railroad work,

welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as b ...

, and

construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and ...

, but can be present in any workplace where hazardous noise is present.

Regulation

In the US, the National Institute for Occupational Safety and Health (NIOSH) and the

Occupational Safety and Health Administration The Occupational Safety and Health Administration'' (OSHA ) is a large regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. Congress established the agen ...

(OSHA) work together to provide standards and regulations for noise in the workplace. National Institute for Occupational Safety and Health (NIOSH),

(OSHA),

Mine Safety and Health Administration The Mine Safety and Health Administration (MSHA) () is a large agency of the United States Department of Labor which administers the provisions of the Federal Mine Safety and Health Act of 1977 (Mine Act) to enforce compliance with mandatory safe ...

(MSHA),

Federal Railroad Administration The Federal Railroad Administration (FRA) is an agency in the United States Department of Transportation (DOT). The agency was created by the Department of Transportation Act of 1966. The purpose of the FRA is to promulgate and enforce rail sa ...

(FRA) have all set standards on hazardous occupational noise in their respective industries. Each industry is different, as workers' tasks and equipment differ, but most regulations agree that noise becomes hazardous when it exceeds 85

decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a ...

s, for an 8-hour time exposure (typical work shift). This relationship between allotted noise level and exposure time is known as an exposure action value (EAV) or

permissible exposure limit The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits are established by the Occupationa ...

(PEL). The EAV or PEL can be seen as equations which manipulate the allotted exposure time according to the intensity of the industrial noise. This equation works as an inverse, exponential, relationship. As the industrial noise intensity increases, the allotted exposure time, to still remain safe, decreases. Thus, a worker exposed to a noise level of 100 decibels for 15 minutes would be at the same risk level as a worker exposed to 85 decibels for 8 hours. Using this mathematical relationship, an employer can calculate whether or not their employees are being overexposed to noise. When it is suspected that an employee will reach or exceed the PEL, a monitoring program for that employee should be implemented by the employer. The above calculations of PEL and EAV are based on measurements taken to determine the intensity of that particular industrial noise. A-weighted measurements are commonly used to determine noise levels that can cause harm to the human ear. There are also special exposure meters available that integrate noise over a period of time to give an L_eq value (equivalent sound pressure level), defined by standards.

Risks of occupational hearing loss

Temporary threshold shift (hearing loss) after noise exposure

Occupational noise, if experienced repeatedly, at high intensity, for an extended period of time, can cause noise-induced hearing loss (NIHL) which is then classified as occupational hearing loss. Most often, this is a type of

sensorineural hearing loss Sensorineural hearing loss (SNHL) is a type of hearing loss in which the root cause lies in the inner ear or sensory organ (cochlea and associated structures) or the vestibulocochlear nerve (cranial nerve VIII). SNHL accounts for about 90% of re ...

. Noise, in the context of industrial noise, is hazardous to a person's hearing because of its loud intensity through repeated long-term exposure. In order for

noise Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference aris ...

to cause

hearing impairment Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken la ...

for the worker, the noise has to be close enough, loud enough, and sustained long enough to damage the hair cells in the auditory system. These factors have been taken into account by the governing occupational health and safety organization to determine the unsafe noise exposure levels and durations for their respective industries. Noise can also affect the safety of the employee and others. Noise can be a causal factor in work accidents as it may mask hazards and warning signals and impede concentration. High intensity noise interferes with vital workplace communication which increases the chance of accidents and decreases productivity. Noise may also act synergistically with other hazards to increase the risk of harm to workers. In particular, toxic materials (e.g. some

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

s, metals, asphyxiants and pesticides) have some ototoxic properties that may affect hearing function. Modern thinking in

further identifies noise as hazardous to workers' safety and health. This hazard is experienced in various places of employment and through a variety of sources.

Reduction

There are several ways to limit exposure to hazardous occupational noise. The hierarchy of controls is a guideline for reducing hazardous noise. Before starting a noise reduction program, base noise levels should first be recorded. After this the company can start to eliminate the noise source. If the noise source cannot be eliminated, the company must try to reduce the noise with alternative methods. This process is called acoustic quieting. Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching the observer. The company can isolate the certain piece of machinery by placing materials on the machine or in between the machine and the worker to decreases the signal intensity that reaches the worker's ear. If elimination and substitution are not sufficient in reducing the noise exposure, engineering controls should be put in place by the employer. An engineering control usually changes the physical environment of a workplace. For noise reduction, an engineering control might be as simple as putting barriers in-between the noise source and the employee in order to disrupt the transmission path. An engineering control might also involve changing the machine that produces the noise. Ideally, most machines should be made with noise reduction in mind, but this doesn't always happen. Changing the machinery involved in an industrial process may not be possible, but is a good way to reduce the noise at its source. Bouchon arceau

To decrease an employee's exposure to hazardous noise, the company can also take

administrative control Administrative controls are training, procedure, policy, or shift designs that lessen the threat of a hazard to an individual. Administrative controls typically change the behavior of people (e.g., factory workers) rather than removing the actu ...

by limiting the employee's exposure time. This can be done by changing work shifts and switching employees out from the noise exposure area. An employer might also implement a training program so that employees can learn about the hazards of occupational noise. Other administrative controls might include restricting access to noisy areas as well as placing warning signs around those same areas. If all other controls fail to decrease the occupational noise exposure to an acceptable level, hearing protection should be used. There are several types of

earplug An earplug is a device that is inserted in the ear canal to protect the user's ears from loud noises, intrusion of water, foreign bodies, dust or excessive wind. Since they reduce the sound volume, earplugs are often used to help prevent heari ...

s that can be used to attenuate the noise to a safe level. Some earplug types include: single-use earplugs, multiple-use ear plugs, and banded ear plugs. Depending on the type of work being done and the needs of the employees, earmuffs might also be a good option. While earmuffs might not have as high of a noise reduction rating (NNR) as earplugs, they can be useful if the noise exposure isn't very high, or if an employee cannot wear earplugs.

Initiatives

Since the hazards of occupational noise exposure were realized, programs and initiatives such as the US Buy Quiet program have been set up to regulate or discourage noise exposure. The Buy Quiet initiative promotes the purchase of quieter tools and equipment and encourages manufacturers to design quieter machines. Additionally, the Safe-In-Sound Award was created to recognize successes in hearing loss prevention programs or initiatives.

References

External links