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 3, 1996

 MEMORANDUM FOR:     Regional Administrators
 FROM:               John B. Miles, Jr., Director
                     Directorate of Compliance Programs
 SUBJECT:            Particulate Respirators Certified under 42
                     CFR Part 84

The Office of Health Compliance Assistance has received numerous questions over the last several weeks questioning the applicability, selection, and use of particulate respirators for workplace exposure to dusts, mists, and fumes. The purpose of this memorandum is to address current issues that have been raised regarding the use, selection, and applicability of the new classes of respirators certified under 42 CFR Part 84. In our September 6, 1995, memorandum to Regional Administrators entitled "Update: OSHA Enforcement Policy for Occupational Exposure to Tuberculosis" we stated the agency would accept these new particulate respirators for use against exposure to Mycobacterium tuberculosis. These respirators are also approved for protection against particulates in all other work environments including construction, maritime, agriculture and manufacturing.

Under the new NIOSH criteria, the filter materials for these respirators are tested at a flow rate of 85 L/minute for penetration by particles with a median aerodynamic diameter of approximately 0.3 um. Three categories of filter (N, R, and P) are designated, each with three levels of filter efficiency (95%, 99%, and 99.97%) for a total of nine respirator classes. The three levels of filter efficiency include the Type 100 (99.97% efficient), Type 99 (99% efficient), and the Type 95 (95% efficient). The classes of these air-purifying, particulate respirators certified under this classification are described in 42 CFR Part 84 Subpart K. (Volume 60 of the Federal Register page 30338, June 8, 1995.) This classification applies only to non-powered (negative pressure) respirators. Respirators certified under this classification replace the dust; dust, mist, fume; and HEPA respirators previously certified under 30 CFR Part 11. For powered air purifying respirators (PAPRs), HEPA filters remain available (42 CFR Part 84 Subpart kk).

The Type 95, Type 99, and Type 100 respirators, are approved for use against particulates by NIOSH and are accepted by OSHA for appropriate use in all work environments. As with other respiratory requirements, the employer must assure that employees required to wear respirators under any OSHA standard are part of a continuing and effective respiratory program as described in 29 CFR 1910.134. Users of respirators should also refer to the "NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84" DHHS (NIOSH) Publication No. 96-101.

Additional questions have been raised about which class of respirator should be used where a particular OSHA standard requires the use of a respirator with HEPA filters. Where workers are exposed to a hazard that would require the use of a respirator with HEPA filters the appropriate class of respirator under the 42 CFR Part 84 certification would be the Type 100. NIOSH has presently designated only the P100 respirator with the magenta color coding. However, the N100, R100, or P100 respirators have been certified at the 99.97% efficiency level and are identified as HEPA respirators.

Users are cautioned to note that the respirator classes are designated for use in certain environments with the P100 being the most universal (hence NIOSH's magenta color coding). Under the new classes of respirators, if oil particles are present, users of respirators must refer to the following guide:

N series -- Not resistant to oil

R series -- Resistant to oil

P series -- oil Proof

For more information or if there are any questions please contact the Office of Health Compliance Assistance at (202) 219-8036.