OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

April 10, 1986

Dr. B. Pfeiffer
Berufsgenossenchafliches Institute
Fur Arbeitssicherheit
Lindenstrasse 80 Postfach 2043
5202 St. Augustin 2 Federal Republic of Germany

Dear Dr. Pfeiffer:

This is in response to your inquiry of July 23 concerning the Occupational Safety and Health Administration's (OSHA) standard for occupational noise exposure. We apologize for the delay in responding.

The standard was first issued on April 17, 1971. On March 8, 1983, it was expanded by adding provisions (c) through (p), called the "Hearing Conservation Amendment." It is mandatory for employers to comply with the standard. OSHA enforces it by conducting unannounced inspections and issuing citations if employers are found not to be in compliance. A copy of the standard is enclosed.

The standard limits employee noise exposure in accordance with a 5-dB exchange rate. Specifically, a 5-dB increase in sound pressure level is permitted for each halving of duration of exposure. It is not permissible to expose any employee in excess of the 90-dBA criterion, which means that no employee may be exposed to the equivalence of a constant sound pressure level of 90 dBA for more than 8 hours, or to the equivalence of a constant sound pressure level 95 dBA for more than 4 hours, and so on.

Employers must make audiometric tests available to employees whose exposure exceeds an 85-dBA criterion, which means that tests must be made available where the exposure to the equivalence of a constant sound pressure level of 85-dBA lasts more than 8 hours, exposure to the equivalence of a constant sound pressure level 90 dBA last more than 4 hours, and so on. Any employee whose audiogram reveals a standard threshold shift (STS), as defined at (g)(10) of the standard, may not be exposed in excess of the 85-dBA criterion.

Employers must use feasible engineering and administrative controls to eliminate employee exposures in excess of the 90-dBA criterion. If the feasible engineering and administrative controls are not fully effective, then the remainder of required protection must be obtained by providing employees with and requiring that they use personal hearing protection devices.

In the case of employees who may not be exposed in excess of the 85-dBA criterion, it is acceptable to reduce their exposure from an amount equaling the 90-dBA criterion to the permissible amount by using personal hearing protection devices.

Thank you for contacting us. If we can assist you again in the future, we shall be glad to do so.


John B. Miles, Jr.





July 23, 1985




US-Department of Labor
Seattle Washington D.C. 98174 U S A

Dear Sirs,

please help us, answering a request on noise legislation in USA:

1. Are OSHA noise regulations mandatory? (Date of issue?)

2. Who is responsible for the implementation? And for inspection?

3, Is the noise exposure still measured as equivalent continuous sound pressure level with q - 5 dB?

4. Which noise limits are in force?

5. Is there priority to noise abatement?

6. Are the wearing of hearing protectors and screening audiometry required in second priority?

Thanks in advance.


(Dr. rer.nat B. Pfeiffer)