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.

September 8, 1987

Mr. Frank M. Parker, III
Environmental Technologies, Inc.
304 Magnolia Boulevard
Magnolia, Texas 77355

Dear Mr. Parker:

This is in response to your inquiry to Mr. Barry J. White requesting a clarification of the requirement for representative monitoring under the asbestos standard for the construction industry (29 CFR 1926.1101). Please accept my apology for the delay in this reply.

Your specific question is how many samples are required in order that they be "representative." First, it should be noted that the requirement for representative monitoring does not preclude an employer from taking individual exposure measurements of each of his employees. Individual measurement is the ultimate indicator of an employee's exposure, however, the Occupational Safety and Health Administration (OSHA) believes that in many work situations the representative monitoring approach can be more cost-effective to accomplish the objectives of the asbestos standard.

There is no specific number of required samples for all situations. The performance monitoring approach of the standard allows employers to use any personal monitoring strategy which identifies the correct employees for inclusion in applicable asbestos standard programs such as but not limited to training, respiratory protection, medical surveillance and employee notification of exposure results.

Thus, in the scenario you described one could sample all of the employees or one could sample on or more employees reasonably expected to have the highest exposure. If representative sampling is used then the 8-hour time weighted average results of those sampled would be attributed to the appropriate remaining exposed employees for the purposes of complying with the asbestos standard.

Your final question asks what statistical method one can use to determine whether employee exposures are below the action level. Like representative monitoring this is not a mandatory requirement nor is there only one method. Please feel free to discuss any specific statistical method you are proposing with our Dallas Regional Office. The address and telephone number are as follows:

Regional Administrator
U.S. Department of Labor - OSHA
555 Griffin Square Building
Griffin and Young Streets
Dallas, Texas 75202

Telephone: (214) 767-4731

I hope this information is helpful. Thank You for your ongoing interest in occupational safety and health.


Thomas J. Shepich, Director
Directorate of Field Programs