Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

December 17, 1991

Mr. James C. Busche
Corporate Safety Engineer
Caterpillar Inc.
100 NE Adams Street
Peoria, Illinois 61629

Dear Mr. Busche:

Thank you for your letter of November 5 detailing your concerns of which baseline to use when measuring occupational related hearing loss for OSHA recordkeeping purposes.

An August 27 memorandum was issued to clarify the OSHA enforcement policy outlined in the June 4 memorandum regarding the recording of hearing loss on the OSHA Form 200. It stated that the "original baseline" must be used when measuring for a 25 dB threshold shift for occupational related hearing loss.

Your decision to utilize the audiogram that was established as a baseline after the issuance of the Hearing Conservation Standard in 1983 is consistent with our definition of "original baseline" for recordkeeping purposes. Once a 25 dB threshold shift from this baseline is identified and recorded on the OSHA Form 200, that audiogram becomes the reference audiogram to which subsequent audiograms are compared. An additional 25 dB shift from the new reference audiogram would result in the recording of a new case on the OSHA Form 200.

Many companies have been recording 10 dB Standard Threshold Shifts (STS's) on the OSHA Form 200. These companies are in full compliance with the enforcement policy contained in the June 4 and August 27 memoranda. If you choose to record STS's, your computer program may be used to meet the requirements of both the Hearing Conservation Amendment (29 CFR 1910.95) and the recordkeeping requirements for the OSHA Form 200 (29 CFR 1904).

We are presently working on a "hearing loss fact sheet" that will clearly outline the issues associated with recording hearing loss on the OSHA Form 200. When it is completed, we will be sure to forward you a copy.

If you have any questions, please contact my staff in the Division of Recordkeeping at (202) 523-1463.


Stephen A. Newell
Acting Director
Office of Statistics