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Occupational Noise Exposure, Ototoxicants & the Year of Sound

EH&S Compliance, Health & Safety Training, Industrial Hygiene

Written by: Virginia McCormick, NES, Inc.

Employers must take certain measures to ensure that their workers are protected from harmful occupational noise exposure.


Occupational Noise Exposure: From Construction Yards to 250 Miles Above Earth

From sports venues to construction yards, occupational noise exposure has largely been accepted as just another workplace hazard. In fact, occupational noise exposure is such a ubiquitous hazard that the fight to combat it reaches all the way to the low Earth orbit. On February 18, the National Institute for Occupational Safety and Health (NIOSH) awarded the 2020 Safe-in-Sound Excellence in Hearing Loss Prevention Award to the Multilateral Medical Operations Panel Acoustics Sub-Working Group for the International Space Station (ISS).

The award, in partnership with the National Hearing Conservation Association and the Council for Accreditation in Occupational Hearing Conservation, honors the, “prevention of noise-induced hearing loss and tinnitus through effective practices or innovations directed to those who are exposed to noise at work.” And while the crew of the ISS face extraordinary challenges regarding occupational noise exposure, everyday employers carry the same responsibility to their own crews.

The Centers for Disease Control and Prevention (CDC) estimates that 22 million workers are exposed to potentially damaging noise at work each year. Additionally, over 30 million workers are exposed to chemicals at the workplace, and some of these chemicals, commonly referred to as ototoxicants, are particularly harmful to the ear and hazardous to hearing.

Regardless of where the workplace is located – from a space station located 250 miles above Earth to a construction yard located at sea level – workers must be protected from occupational noise exposure, and employers must take the necessary measures to ensure that protection.


Methods for occupational noise exposure mitigation can vary greatly between jobsites, but all job-related hearing loss can be prevented.


Federal & California Occupational Noise Exposure Regulations

The first recommended occupational noise exposure limit in the U.S. was promulgated by the U.S. Air Force in the late 1940s. In 1956, the Air Force limits were updated to specify seven components of effective hearing loss prevention: noise measurement, noise control, hearing protection, audiometric testing, training, recordkeeping, and program evaluation. These components are still recognized in modern occupational noise exposure prevention programs.

Many regulations outlined in federal and state occupational health & safety plans differ slightly, with state plans being required to be at least as strict as their federal counterparts. In terms of federal OSHA versus the California Occupational Safety and Health Administration (Cal/OSHA), noise exposure regulations are roughly the same.

The federal code of regulations, located under 29 CFR 1910.95, identifies 85 decibels (dB) averaged over 8 working hours as the action level – that is, the threshold at which general industry employers must implement a hearing conservation program. OSHA’s permissible exposure limit (PEL) for noise is 90 dB averaged over 8 working hours. There are additional requirements for employers to follow when the PEL is reached, such as requiring the use of hearing protection and providing annual audiometric testing. California’s occupational noise exposure regulations are located under 8 CCR 5095-5100. The California action level and PEL for noise exposure are the same as federal OSHA (85 dB and 90 dB, respectively).

OSHA and Cal/OSHA exposure limits only cover occupational noise exposure, not general environmental noise. According to the American Speech-Language-Hearing Association, occupations that entail occupational noise exposure cover a broad range, from construction workers, to military service members, to musicians.


Decibels are measured on a logarithmic scale, not a linear one. Sound levels are doubled every time a measurement goes up by 3 dB, so the difference between 80 dB and 90 dB is significant. (Source: American Academy of Audiology)


Like many other workplace hazards, NIOSH recommends employers utilize the Hierarchy of Control to determine how to implement effective occupational noise exposure control methods. Elimination or substitution are the preferred mitigation methods. NIOSH recommends that employers utilize the Buy Quiet initiative, which promotes the purchasing/renting of quieter machinery and tools.

Personal protective equipment (PPE) such as earplugs or earmuffs should be made available to workers at no cost. As the lowest rung on the Hierarchy of Controls, PPE is implemented only after options for eliminating or reducing noise at its source are not feasible. NIOSH’s free sound level meter application for mobile devices can make it easy to monitor a worker’s noise environment.

For more information on hazard control methods, see the April 2019 NES blog NIOSH’s Hierarchy of Controls.



According to a 2018 OSHA safety bulletin, exposure to certain chemicals on the jobsite may create a greater risk of hearing loss than occupational noise exposure alone. These chemicals are known as ototoxicants, which are defined as, “any substance, including drugs or industrial chemicals, that is toxic to the auditory system.” Ototoxicants often reach the inner ear through the blood stream and can cause injury to connected neural pathways. And while employers are required to maintain noise exposure below the 90 dB PEL, the bulletin notes that, “effects from the combined ototoxicant and noise exposure could result in hearing loss when exposures are below the PEL.

The OSHA safety bulletin outlines several types of ototoxicants, such as solvents like toluene and asphyxiants like carbon monoxide; however, it is not an exhaustive list. Exposure thresholds for chemicals vary, depending on, “exposure route and duration, additive effects with noise exposure, and individual risk factors.” Employers and workers are encouraged to consult a chemical’s Safety Data Sheet (SDS) to identify a potential ototoxicant.


Exposure to ototoxicants commonly found in workplaces, such as carbon monoxide in repair shops, may affect hearing alone or in combination with other occupational noise exposure.


Industries that commonly use ototoxicants include manufacturing, mining, utilities, and construction. These industries often have increased levels of noise exposure to begin with, making the risk of hearing loss even higher. A study published in the American Journal of Industrial Medicine reported that as many as 1 in 3 mine workers suffer hearing loss. And while much of that hearing loss was assumed to have originated from noise exposure, chemical exposure was also identified as a risk factor.


The Year of Sound: Raising Occupational Noise Exposure Awareness

NIOSH identifies several reasons why hearing conservation is so vital in the workplace. Along with basic hearing loss, occupational noise exposure has the potential to:

  • Decrease employee safety and comfort levels
  • Increase isolation, depression, and risk of cognitive decline and heart problems
  • Develop into permanent conditions, such as tinnitus (ringing in the ears)

Luckily, the CDC notes that occupational noise exposure and hearing loss can be, “entirely prevented with today’s … prevention strategies and technology.” In January of 2020, NIOSH launched a year-long campaignWiki4YearOfSound2020 – to better provide free public information on the harmful effects of noise exposure. Several additional organizations, such as the International Society of Audiology and the National Hearing Conservation Association, have also joined the campaign.

Wiki4YearOfSound2020 centers around the internet encyclopedia, Wikipedia, and was created in honor of a global initiative – the International Year of Sound 2020 (IYS2020). The campaign is just one part of IYS2020, which highlights the, “importance of sound and related sciences and technologies for all in society.” It hoped that, by providing and promoting free access to information on noise exposure, the campaign and ITS2020 will raise the awareness of the many preventative measures employers can use to mitigate occupational noise exposure. At the time of this publishing, the Wiki4YearOfSound2020 campaign has prompted more than 2,500 edits, 48,000 words, and 20 new articles relating to sound.


The Year of Sound 2020 highlights the importance of understanding sound in many different aspects of life – including on the job.


NES & Occupational Noise Exposure

Section 5(a)(1) of OSHA’s General Duty Clause requires employers to “furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees.” Training workers on identifying potential hazards, such as occupational noise exposure, and the proper control methods to deal with those hazards is the best way to promote safety at a worksite.

NES has been providing occupational health and safety training and construction safety oversight services on behalf of a wide array of public and private businesses and government agencies for the past 30 years. For more information on how we can help you manage the health and safety of your employees, please contact NES at 916-353-2360 / 1-800-NES-ADVISE (1-800-637-2384) or



NIOSH and Partners Announce 2020 Safe-in-Sound Excellence in Hearing Loss Prevention Award™

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Noise and Hearing Loss Prevention

Occupational noise exposure: A review of its effects, epidemiology, and impact with recommendations for reducing its burden

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OSHA Warns Workers about Hearing Loss from Ototoxicant Exposure

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