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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.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

November 14, 1991

Ms. Cynthia H. Drollinger
HCI, Inc.
810 East State Street
Rockford, Illinois 61104

Dear Ms. Drollinger,

Thank you for your letter of August 16 concerning the recording of Standard Threshold Shifts (STS) on the OSHA 200 log. The 25 dB shift criteria represents a long standing Federal enforcement position. It establishes the level of work-related hearing loss that must be recorded on the OSHA 200 log. However, we do encourage the recording of lower dB shifts. Please be aware that this criteria in no way affects the 29 CFR 1910.95 requirements. All requirements in that regulation are still in full force and effect. The following answers address the questions in the same order as presented in your letter:

a. Yes. The 10 dB criteria for STS in 29 CFR 1910.95 does not require entry on the OSHA 200 log. Recording and reporting of occupational injuries and illnesses is controlled by 29 CFR 1904.

b. An annual audiogram may be substituted for a baseline audiogram when, in the judgment of the audiologist, otolaryngologist or physician who is evaluating the audiogram: 1) The standard threshold shift revealed by the audiogram is persistent; or 2) The hearing threshold shown in the annual audiogram indicates significant improvement over the baseline audiogram. Otherwise, decisions on revising audiogram baselines must continue to be based on events of standard threshold shifts (STSs) as defined at 29 CFR 1910.95(g)(10).

c. The 25 dB criteria is a Federal enforcement criteria. The State Plan States may adopt this criteria or enforce the recording of lower work-related shifts. It is their option.

1. There is no reference to this criteria in OSHA documents. The 25 dB criteria is based on guidance found in the American Medical Associations Guide to the Evaluation of Permanent Impairment. This threshold criteria was chosen because it is widely accepted as a meaningful loss of hearing and is well documented.

2. The measurement of the 25 dB shift should begin from the employees original baseline.

3. The revised baselines should not be used to track the new 25 dB shift. The original baseline should be used.

4. A 25 dB shift from revised baselines for persistent 10 dB shifts would be rather unusual. However we are requiring that the original baseline be used for the measurements, not the revised baselines.

5. Yes, therefore we are using the original baseline to make the measurements.

6. The 25 dB shift criteria has no impact at all on the 29 CFR 1910.95 requirements. All requirements in that regulation still apply.

The 25 dB shift has no new impact on the recordability of shifts for employees who are exposed to less than 85 dB time-weighted average. As in the past, work-relationship must first be determined. If the work environment caused, aggravated, or contributed to the 25 dB shift, then the case must be recorded.

Let me assure you that the 10 dB STS recordability criteria will be examined carefully during the regulatory revision we have begun for 29 CFR 1904. A revised set of supplementary instructions to the OSHA 200 and 101 forms will also be included. As mentioned earlier, the 25 dB criteria is an already existing OSHA enforcement position on recording work-related hearing loss.

If you have any questions, please contact my Office of Statistics at (202) 523-1463.


Gerard F. Scannell
Assistant Secretary

August 16, 1991

OSHA CCU # 9103240

The Honorable Gerard Scannell
Assistant Secretary for Occupational
Safety & Health Administration
200 Constitution Avenue, N.W. - Room A-2315
Washington, D.C. 20210

Dear Mr. Secretary:

We are in receipt of your memorandum of June 4, 1991 for OSHA Regional Administrators and would appreciate some clarification regarding the new 25 dB criteria for recording Standard Threshold Shifts on the OSHA 200 log. As a nationwide firm in the audiometric testing business, our client companies naturally look to us for guidance in compliance issues.

a. Does the memo mean that the current 10 dB criteria for Standard Threshold Shift in 29 CFR 1910.95 does not require entry on the OSHA 200 log?

b. If no log entry is required, is the baseline revision still required?

c. Are state programs such as Tennessee's where employers have been cited for failing to record 10 dB STS's going to follow the criteria presented in your memo?

The 25 dB criteria that is now required to make log entries is unfamiliar to us.

1.) Is there an existing reference to this criteria in OSHA documents, or is this completely new?

2.) At what point are we to begin the measurement of the 25 dB shift?

3.) Since we regularly revise baselines for persistent 10 dB shifts, are we to use those current revised baselines to track the new 25 dB shift criteria or is there another point in time where this measurement is to begin?

4.) As we continue revising baselines for persistent 10 dB shifts, would it not be rather unusual for noise exposure to cause a 25 dB shift before the next persistent 10 dB shift with its resulting baseline revision?

5.) In other words, if noise exposure causes the classic pattern of hearing loss in the higher frequencies over a period of years, would it not be most common for a person to experience a series of 10 dB shifts and never a 25 dB shift?

6.) If a 25 dB shift is identified, is the employee notification, baseline revision and employer follow-up the same as is currently required by 29 CFR 1910.95?

Many employers test employees who are exposed to less than 85 dB time-weighted average. What, if any, impact does the new 25 dB shift criteria have on the recordability of shifts to such employees?

We were told this Spring by the presenters at your Recordkeeping Seminars that 10 dB STS recordability was the intended goal at OSHA. Is 25 dB the interim criteria while the guideline language is being changed to make 10 dB the permanent standard?

I am sure your office, like ours, has been inundated with questions about these matters. We feel compelled as I am sure you do, to give accurate answers and make the necessary modifications to our reports, so they are consistent with the current regulatory requirements. Please answer our query as expeditiously as possible, so we may clarify the letter and intent of these new changes to our clients and others. We would appreciate your prompt attention to this matter.

Very truly yours,

Cynthia H. Drollinger