OSHA Decibel Requirements

As part of its mandate to assure working men and women safe and healthful working conditions, the U.S. Department of Labor's Occupational Health and Safety Administration (OSHA) has regulations in place to protect the hearing of workers exposed to excessive noise. Noise decibel (dB) level is one of the factors considered by the agency, as is the duration of the worker's exposure to the loud noise and whether or not the worker's duties take him into areas with different decibel levels.

Loudness (decibels)

• Loudness is obviously the first consideration. If the noise is kept below 85 dB no hearing protection is required, and employers are expected to make all possible engineering and design efforts to keep the noise to a minimum. For any noise exposure above 85 dB for at least eight hours a day, the employer is required to furnish OSHA-approved hearing protection to the employee at no cost. In addition, employers are responsible for that exposed employees use their hearing protection.
  According to a 1999 interpretation letter (updated in 2008) from OSHA's Directorate of Compliance Programs, there is evidence that connects consistent noise exposure at 95 dB and above to problems beyond hearing loss. According to the letter, disorders of the cardiovascular, digestive, respiratory, allergenic and musculo-skeletal systems, as well as disorientation and reduction of eye focus, can be linked to such exposure.

Duration of Exposure

• Extremely loud noise can cause instant physiological damage, but lower levels of continuous noise do damage over time. Noise is considered continuous if the interval between the maximum noise levels is one second or less, and OSHA has different limits for periods of exposure to different continuous noise levels. For example, a worker may be exposed to an average noise level of 90 dB for a maximum of eight hours per day, 95 dB for four hours per day, 105 dB for one hour per day, and 115 dB for 15 minutes per day.

Different Noise Levels

• Empolyers must provide hearing protection where needed.

  Some employees' work requires their exposure to different decibel levels during a day. When that is the case, the employee's combined exposure level is considered. The amount of time exposed to each decibel level is divided by the permissible time for that decibel level. The resulting values are added together, and if they exceed 1.0, exposure has exceeded the permissible limit.