Occupational Noise Exposure
The Occupational Safety and Health Administration (OSHA) regulates occupational noise exposure in 29 CFR 1910.95. OSHA measures occupational noise exposure using an 8-hour time-weighted average (TWA). There are numerous steps that employers are required to take when employees are exposed to different noise levels.
Important occupational noise exposure provisions
Permissible Exposure Limit: OSHA’s permissible exposure limit for occupational noise is 90dBA as an 8-hour TWA. OSHA uses a 5dBA exchange rate, which means that for every 5dBA over 90dBA, the exposure time is halved. For example, if an employee’s noise exposure is 100dBA, the permissible exposure time is only 2 hours.
Noise Exposure Controls: Before providing employees with hearing protectors, such as earmuffs or earplugs, all engineering and administrative controls must first be implemented. Engineering controls reduce sound levels at the source or in the path of the sound waves, while administrative controls are changes in the workplace that reduce employees’ noise exposure.
Administrative controls may include limiting the amount of time an employee spends in a noisy environment or operating machinery when fewer employees are in the work area. Any hearing protectors must provide adequate noise protection for each employee provided with the hearing protection.
Monitoring: Whenever an employer has reason to believe an employee may have noise exposure exceeding the 85dBA action level, the employer must implement a monitoring program.
The monitoring program must identify employees that have to be included in the hearing conservation program. Monitoring must accurately reflect the employees’ noise exposure levels. Whenever there is a change in production, process, or equipment that may impact employees’ exposure levels, the monitoring must be repeated.
Recordkeeping: Employers are required to maintain records for employees affected by occupational noise exposure. Noise exposure measurements must be retained for two years, and audiometric test records must be retained for as long as an employee works for the employer.
Training: All employees exposed to an 8-hour TWA of 85dBA or more must be trained annually. This training must include the effects of noise exposure, the types of hearing protectors, and the purpose of audiometric testing and its procedures.
What is a time-weighted average?
Time-weighted average is the average amount of a substance a worker can be exposed to over an eight-hour day.
What is dBA?
Noise is measured in decibels (dB). OSHA measures noise exposure using A-weighted sound levels (dBA) which matches the perception of sound by the human ear. Decibels are measured on a logarithmic scale, so small changes in the number of decibels can mean a large increase in the noise levels experienced by workers.