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Standard Interpretations - Table of Contents
• Standard Number: 1910.134; 1910.134(b); 1910.134(c)(2); 1910.134(h)

November 22, 2011

Mr. Edwin G. Foulke
Fisher & Phillips LLP
1075 Peachtree Street, NE
Suite 3500
Atlanta, GA 30309

Dear Mr. Foulke:

Thank you for your letter of April 11, 2011, to the Occupational Safety and Health Administration (OSHA) requesting clarification on several provisions in OSHA's respiratory protection standard. Each of your questions has been paraphrased below, followed by our response. This letter constitutes OSHA's interpretation only of the requirements discussed, and may not be applicable to any question not delineated in your original correspondence.

Question 1: How does OSHA define a filtering facepiece/dust mask?

Response: A filtering facepiece respirator is defined in 29 CFR 1910.134(b) as "a negative pressure particulate respirator with a filter as an integral part of the facepiece or with the entire facepiece composed of the filtering medium."

Question 2: How does OSHA differentiate between a filtering facepiece and a respirator?

Response: As stated above, a filtering facepiece is a negative pressure respirator. It is considered to be in the same category as an elastomeric half-mask respirator, and both respirators have an assigned protection factor (APF) of 10.

Question 3: What is the difference between a "demand respirator" and a "negative pressure respirator"?

Response: A "demand respirator," as defined in 29 CFR 1910.134(b), is an atmosphere-supplying respirator that admits breathing air only when a negative pressure is created in the facepiece by inhalation. A "negative pressure respirator" is any respirator in which the air pressure inside the facepiece is negative during inhalation with respect to the ambient air pressure outside the respirator.

Question 4: Is an N95 respirator a filtering facepiece respirator, or is it either a demand respirator or a negative pressure respirator?

Response: An N95 respirator is an air-purifying negative pressure respirator equipped with an N95 filter. If the filter is an integral part of the facepiece, or the entire facepiece composed of the filtering medium, the respirator is also considered a filtering facepiece respirator.

Question 5: In a situation where an employee is working in an area with minor dust exposure, where no respiratory hazards exist, and where an employee is voluntarily using an N95 filtering facepiece respirator, does this use fall within the scope of the exception provided in paragraph 1910.134(c)(2)(ii)?

Response: Yes; according to the exception, if the employer allows N95 filtering facepiece respirators to be voluntarily used by employees in areas that have no respiratory hazards, the employer is not required to include these employees in a written respiratory protection program.

Question 6: Which provisions of the respiratory protection standard must be followed when an N95 filtering facepiece respirator is voluntarily used?

Response: If the employer allows employees to voluntarily use filtering facepiece respirators, the employer must follow the appropriate provisions in (c)(2). The employer must determine that such respirator use will not in itself create a hazard (i.e., by ensuring that masks are not used if dirty or contaminated, and that their use does not interfere with the employee's ability to work safely). The employer also must provide the information in Appendix D to each voluntary wearer.

Question 7: If OSHA considers the N95 filtering facepiece a respirator covered by the respiratory protection standard, what parts of paragraph (h) involving "maintenance and care of respirators" are applicable? Does the employer have to comply with Appendix B-2 involving "Respirator Cleaning Procedures"?

Response: The N95 filtering facepiece respirator is a "disposable respirator." It must be discarded after use, or when it becomes damaged or soiled. It cannot be cleaned and disinfected according to the method described in Appendix B-2. OSHA is presently not aware of any alternate procedures provided by respirator manufacturers in their user instructions that would allow for cleaning and disinfecting their filtering facepiece respirators.

Many requirements in paragraph (h), however, would still be applicable to N95 filtering facepiece respirators. For example, employers must provide respirators that are clean, sanitary, and in good working order [(h)(1)]. If a respirator cannot be cleaned and disinfected, it may not be used by more than one user [(h)(1)(ii)], and, once soiled or contaminated, it can no longer be maintained in a sanitary condition [(h)(1)(i)] and must be discarded. If respirators are to be reused, they must be stored to protect them from damage, contamination, dust, sunlight, extreme temperatures, excessive moisture, and damaging chemicals; and they must be stored to prevent deformation of the facepiece or exhalation valve [(h)(2)(i)]. Employers must also ensure the respirators are inspected before each use [(h)(3)(i)(A) and (ii)]. Respirators that fail an inspection, or are otherwise found to be defective, must be removed from service [(h)(4)].

Thank you for your interest in occupational safety and health. We hope you find this information helpful. 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 http://www.osha.gov. If you have any further questions, please feel free to contact the Office of Health Enforcement at (202) 693-2190.


Thomas Galassi, Director
Directorate of Enforcement Programs

Standard Interpretations - Table of Contents

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