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.

April 17, 1997

Leon Petrakis, Senior Scientist
Brookhaven National Laboratory
Associated Universities, Inc.
Post Office Box 5000
Upton, New York 11973-5000

Dear Mr. Petrakis:

Thank you for your letter of January 21, where you provided information on the development of a product that is applied to asbestos-containing fireproofing to reduce the asbestos content too less than one percent.

The encapsulant product that is described in your letter is applied as a foam, and "chemically destroys asbestos-containing fireproofing, producing a safe, non-asbestiform substance." You are correct in stating under the Occupational Safety and Health Administration's (OSHA) Occupational Exposure to Asbestos Standard, 29 CFR 1926.1101, encapsulation is a Class III operation. The standard requires that the employer assure a qualified person conduct an exposure assessment to document that exposure to employees is below the 8-hour time weighted average of 0.1 fiber per cubic centimeter and the 30 minute Excursion Limit (EL) of 1.0 fiber per cubic centimeter. The informational materials you provided did not contain a sufficient data base of representative employee samples, nor did it contain other kinds of objective data that could fully predict future exposure to asbestos on construction jobs.

Your letter states that "assuming the product is successful in reducing the amount of asbestos to less than one percent", your understanding is that fireproofing treated with your encapsulant would no longer contain asbestos or be considered asbestos-containing material (ACM). It is accurate to say fireproofing that contains less than one percent asbestos is not ACM by OSHA's definition. The one percent cut off is consistent with EPA's definition under the asbestos National Emission Standards for Hazardous Air Pollutants (NESHAP). However, the OSHA standard has a definition for both "asbestos" and "asbestos-containing materials." The definition of asbestos does not have a one percent cut off, therefore, asbestos that is present in percentages less than one percent continues to be covered by the OSHA standard. Work operations conducted in areas where the asbestos or asbestos product is below one percent is an "unclassified" operation. The employer still must follow the requirements in paragraphs (g)(1) [except (g)(1)(i)], (g)(2) and (g)(3) that describe engineering and work practice controls operation.

We hope this has provided you with the information you requested. If you have further questions, please feel free to contact [the Office of Health Compliance Assistance at (202) 693-2190].


John B. Miles Jr., Director
Directorate of Compliance Programs