From the Guidelines
Permitted occupational noise exposure levels should not exceed 85 decibels (dB) averaged over an 8-hour workday, as levels above this threshold significantly increase the risk of noise-induced hearing loss (NIHL) 1.
Key Considerations for Noise Exposure
- The 8-hour time-weighted average (TWA) is the standard measure for occupational noise exposure, with levels above 85 dB requiring implementation of a hearing conservation program.
- For every 3 dB increase above 85 dB, the permitted exposure time is cut in half, highlighting the importance of minimizing exposure to high noise levels.
- The absolute maximum permissible exposure level is typically 140 dB for impact or impulse noise, emphasizing the need for stringent controls in high-risk environments.
Prevention and Monitoring of NIHL
- Engineering and administrative controls, hearing protection devices, and regular audiometric testing are crucial for preventing NIHL 1.
- Pure-tone audiometry is currently the most effective method for detecting early signs of NIHL, although it only identifies permanent changes in hearing.
- Monitoring temporary threshold shift (TTS) incidents after exposure to noise may offer a promising approach to preventing permanent hearing loss, as it can indicate potential damage before irreversible changes occur.
Importance of Personalized Prevention
- Individual factors determining susceptibility to noise should be taken into account when developing medical guidelines for the prevention of NIHL 1.
- Personalized approaches can help mitigate the high incidence of occupational NIHL, which remains a significant occupational disability worldwide.
From the Research
Permitted Occupational Noise Exposure Levels
- The permitted occupational noise exposure levels are typically set at 85 dBA, as repeated overexposure to noise at or above this level can cause permanent hearing loss, tinnitus, and difficulty understanding speech in noise 2.
- Exposure to noise levels above 85 dBA can also lead to other health problems, such as cardiovascular disease, depression, balance problems, and lower income 2.
- The National Institute for Occupational Safety and Health (NIOSH) recommends that workers not be exposed to noise levels above 85 dBA for more than 8 hours per day 2.
Noise Exposure Limits in Different Industries
- The Mining, Construction, and Manufacturing sectors typically have the highest prevalence of noise exposure and hearing loss 2.
- Workers in these industries are often exposed to noise levels above 85 dBA, and may be at risk of developing noise-induced hearing loss (NIHL) 2.
- Other industries, such as military aviation, transcription, and call centers, may also have workers who are exposed to high noise levels, particularly if they use communication headsets or headphones 3.
Use of Hearing Protection Devices
- The use of hearing protection devices, such as earplugs or earmuffs, can help reduce the risk of NIHL 4.
- Earplugs have been shown to be effective in preventing temporary hearing loss after loud music exposure, with a relative risk reduction of 5.3 compared to unprotected ears 4.
- Active noise control technology applied to earphones can also help reduce the preferred listening levels in noisy environments, potentially reducing the risk of recreational noise-induced hearing loss 5.
Measurement of Noise Exposure
- Noise exposure can be measured using various techniques, including sound pressure level (SPL) measurements and questionnaire surveys 3.
- The diffused-field-related A-weighted equivalent-continuous SPLs can be used to evaluate the risk of NIHL, with values above 85 dBA indicating a potential risk 3.
- Individual daily noise exposure levels can vary widely, and may be influenced by factors such as the type of industry, job tasks, and use of hearing protection devices 3.