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 26, 1994

Ms. Janet Fox
Director, Industrial Hygiene and Safety Services
Occupational Health Department
Consolidated Edison, Company of New York, Inc.
30 Flatbush Avenue
Brooklyn, New York 11217

Dear Ms. Fox:

Thank you for your letter of November 22, 1993 concerning the Occupational Safety and Health Administration's (OSHA) Hazardous Waste Operations and Emergency Response (HAZWOPER) regulation, 29 CFR 1910.120, and Asbestos regulation for construction, [29 CFR 1926.1101]. We apologize for the delay in this reply.

You request clarification on the use of direct reading instruments during the initial response phase to an emergency release of asbestos, and whether the results of such real-time monitoring may be used for the downgrading of the level of personal protective equipment (PPE) in use. You also inquire whether the OSHA Asbestos standard would apply to an emergency release of asbestos.

Elements of both the HAZWOPER and Asbestos standards would apply to any emergency response to an uncontrolled hazardous substance release involving the presence of asbestos. Further, paragraph (a)(2)(i) of 29 CFR 1910.120 states that where HAZWOPER overlaps with another OSHA standard, the provision which is more protective of employee safety and health shall apply.

The monitoring requirements of the Asbestos standard are more protective than those of the HAZWOPER standard. The Asbestos standard requires that determination of employee exposure levels be based upon full shift and 30 minute breathing zone air samples of employees with representative exposures, which are to be evaluated in accordance with the OSHA Reference Method or an equivalent counting method [see 29 CFR 1926.1101 Appendix A]. Unless the method meets the monitoring equivalency criteria in [1926.1101(f)(2)(ii)], the use of real-time monitoring instruments as the basis for PPE selection for protection against asbestos is not permitted, and PPE cannot be downgraded during emergency response operations involving asbestos exposure until appropriate sampling data are available.

Where asbestos is the only hazardous substance present, you may follow the specifications in the asbestos standards with regard to PPE selection. If the airborne concentration of asbestos fibers is unknown, then full facepiece, supplied air respirators operated in pressure demand mode and equipped with auxiliary positive pressure self-contained breathing apparatus shall be used [see 29 CFR 1926.1101(h)(3)(i)]. This level of PPE is required until appropriate air monitoring results indicate that a lesser level of respiratory protection is adequate.

Where other inhalation hazards may be present along with asbestos, you must comply with paragraph (q)(3)(iv) of 29 CFR 1910.120, which requires that emergency responders exposed or potentially exposed to an inhalation hazard shall wear self-contained breathing apparatus (SCBA) until air monitoring results indicate that a lesser level of respiratory protection is adequate. Where accurate direct reading instruments are available for the substance in question, HAZWOPER permits their use as the basis for selection/downgrading of PPE, unless another applicable standard (i.e., a substance-specific expanded health standard) specifies a more protective approach.

We hope this information is helpful. If you have any further questions please contact us at (202) 219-8036.


Ruth E. Mccully, Director
Office of Health Compliance Assistance