NIOSH vs OSHA Exposure Limits

The National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) both have regulations in place to protect workers from noise-induced hearing loss. However, the two agencies use slightly different standards for determining the level of noise exposure that requires hearing conservation measures.

Let’s start by making sure we understand the method used by NIOSH and OSHA to measure noise. The Time Weighted Average (TWA) is a method used to measure the average level of noise exposure over a certain period of time. It is typically measured in decibels (dB) and is calculated by taking the sum of the product of the noise level and the duration of exposure, divided by the total duration of exposure. This allows for a more accurate measurement of noise exposure, as it takes into account variations in noise levels and duration of exposure throughout the workday.

OSHA's hearing conservation program is outlined in 29 CFR 1910.95, which is the Occupational Noise Exposure standard. The standard requires employers to measure noise levels in the workplace and to establish a hearing conservation program if noise exposure exceeds an 8-hour time-weighted average (TWA) of 85 decibels (dB). The standard also requires employers to provide annual audiometric testing to employees who are exposed to noise levels above the permissible exposure limit (PEL) of 90 dB TWA. Additionally, the standard requires employers to provide employees with hearing protection devices and to train employees on how to use and care for the devices.

NIOSH, on the other hand, has a recommended exposure limit (REL) of 85 dB TWA for an 8-hour workday, with a recommended action level of 80 dB TWA. Unlike OSHA, NIOSH does not have legally enforceable standards. However, NIOSH recommends that employers establish a hearing conservation program if noise exposure exceeds the action level of 80 dB TWA. This program should include monitoring noise levels, providing hearing protection devices, and offering annual audiometric testing to exposed employees. Additionally, NIOSH recommends that employers consider engineering controls, such as noise barriers and sound-absorbing materials, to reduce noise levels in the workplace.

It is important to note that both OSHA and NIOSH also have regulations in place for peak noise levels, which are short-term, high-intensity noise events. OSHA's permissible peak noise level is 140 dB, while NIOSH's recommended peak noise level is 140 dB. Employers are required to take steps to protect workers from exposure to peak noise levels, such as providing earplugs or earmuffs, or implementing engineering controls.

It's worth noting that NIOSH's recommendations are considered more protective than OSHA's standards, as they aim to prevent hearing loss from occurring in the first place, whereas OSHA's standards focus on mitigating the effects of hearing loss after it has already occurred. Employers are not obligated to follow NIOSH recommendations, but many choose to do so in order to protect their employees from noise-induced hearing loss. When you consider that an employee hearing loss injuries results in a 46% increase in health insurance expense over a 10-year period, it’s it easy to see why simply being compliant with OSHA may not be the most cost effective approach.

“Untreated hearing loss resulted in a 46% increase in total health care costs over a 10-year period compared with costs for those without hearing loss”

— JAMA Otolaryngol

In summary, OSHA's permissible noise exposure limit is 90 dB TWA for an 8-hour workday, and employers are required to establish a hearing conservation program if noise exposure exceeds 85 dB TWA for an 8-hour workday. NIOSH, on the other hand, recommends a lower exposure limit of 85 dB TWA for an 8-hour workday, and an action level of 80 dB TWA for an 8-hour workday, at which employers should begin to implement a hearing conservation program, even if the TWA exposure level is below 85 dB.

Still have questions? Contact us and a licensed Occupational Hearing Conservationist on the Soundtrace team will be in touch!