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 https://www.osha.gov.

May 23, 1985

Richard C. Gerlach, Ph.D., CIH
Vice President-Technical Services
Industrial Health Foundation, Inc.
34 Penn Circle
West Pittsburgh, Pennsylvania 15206

Dear Dr. Gerlach:

This is in response to your letter of April 26, inquiring how the Occupational Safety and Health Administration (OSHA) makes exposure compliance determinations for substances regulated under Subpart Z of 1910.

Such determinations consider many factors. Careful attention to workplace conditions (e.g., production levels, control integrity, work practices, etc.) is paid to ensure that representative samples are collected. Employer sampling data, when available, is evaluated first for reliability and then for comparability with OSHA results.

OSHA sampling is repeated when major discrepancies arise between employer and OSHA results that cannot be accounted for. In addition, where feasible, the relative results of direct reading and other analytical results are considered. (For example, outlier results are discounted and sampling is repeated.)

Thus, when OSHA determine that employee exposure to a regulated substance exceeds the permissible limits prescribed by our standards, we then also assess employer compliance with all other applicable provisions of the standard that are dependent on employee exposure levels.

Please feel free to contact us if further assistance is needed. I hope this information answers your question.


John B. Miles, Jr., Director
Directorate of Field Operations

April 26, 1985

Mr. Robert A. Rowland
U.S. Department of Labor-OSHA
200 Constitution Avenue, N.W.
Washington, D.C. 20010

Dear Mr. Rowland:

Recently, one of Industrial Health Foundation's clients contacted IHF and inquired as to the procedures used by OSHA during inspections to determine compliance with Subpart Z - Toxic and Hazardous Substances of the General Industry Standards. In particular, the client stated that is was their impression that if a CSHO measured an employee exposure to a regulated material and found a Noncompliance Exposure, OSHA would conclude that such Noncompliance Exposures were the rule rather than the exception, and expect the employer to comply (in the case of exposures to materials such as asbestos, coke oven emissions and arsenic) with all applicable provisions of the relevant standard. As a result, assuming this scenario is accurate, our client has asked us to attempt to ascertain OSHA's rationale for this policy. Therefore, IHF is respectfully submitting this request to OSHA.

Thank you for your assistance with this matter.


Richard C. Gerlach, Ph.D., CIH
Vice President-Technical Services