Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

September 6, 1995



MEMORANDUM FOR: Regional Administrators
National Office Directorates
Area Directors
FROM: John B. Miles, Jr., Director
Directorate of Compliance Programs
SUBJECT: Update: OSHA Enforcement Policy for Occupational Exposure to Tuberculosis


This memorandum provides revised enforcement policy for respiratory protection for occupational exposure to Tuberculosis (TB). In October of 1994, following a call for comments by the CDC, an updated and revised set of guidelines on TB exposure control procedures and recommendations was issued.

The 1994 CDC Guidelines addressed respirators for occupational exposure to TB and specified standard performance criteria for respirators upon exposure to TB These criteria include:






  1. The ability to filter particles 1 µm in size in the unloaded state with a filter efficiency of greater than or equal to 95% (i.e., filter leakage of less than or equal to 5%), given flow rates of up to 50 L per minute.
  2. The ability to be qualitatively or quantitatively fit tested in a reliable way to obtain a face-seal leakage of less than or equal to 10%.
  3. The ability to fit the different facial sizes and characteristics of health care workers which can usually be met by making the respirators available in at least three sizes.
  4. The ability to be checked for a face piece fit, in accordance with OSHA standards and good industrial hygiene practice, by health care workers each time they put on their respirator.

NIOSH recently issued their revised respirator certification criteria. Under the new NIOSH criteria filter materials would be tested at a flow rate of 85 L/minute for penetration by particles with a median aerodynamic diameter of 0.3 µm. Three classes of filter (N, R, and P) will be certified with three levels of filter efficiency (95%, 99%, and 99.97%) in each class resulting in a total of nine respirator classes. The three classes or levels of filter efficiency include the Type 100 (99.97% efficient), Type 99 (99% efficient), and the Type 95 (95% efficient), NIOSH has determined that any of these classes of respirators meet the filter efficiency criteria of the CDC for protection against TB. Based upon these criteria, the minimally acceptable level of respiratory protection for TB is the N-95 respirator. These respirators must be certified by NIOSH and meet the four criteria previously described. The classes of these air-purifying, particulate respirators to be certified are described under 42 CFR Part 84 Subpart K. (Volume 60 of the Federal Register page 30338, June 8, 1995.) Until these classes of respirators are commercially available the minimal acceptable respiratory protection meeting the criteria will remain the HEPA respirators. A facility may continue to use HEPA respirators if they so choose.

Respiratory protection (HEPA or respirators certified under 42 CFR Part 84 Subpart K) for employees exposed to TB is required under the following circumstances:





  1. When workers enter rooms housing individuals with suspected or confirmed infectious TB.
  2. When workers are present during the performance of high hazard procedures on individuals who have inspected or confirmed infectious TB.
  3. When emergency-medical-response personnel or others transport, in a closed vehicle an individual with suspected or confirmed infectious TB.

If a facility chooses to use disposable respirators as part of their respiratory protection program, their reuse by the same health care worker is permitted as long as the respirator maintains its structural and functional integrity and the filter material is not physically damaged or soiled. The facility must address the circumstances in which a disposable respirator will be considered to be contaminated and not available for reuse.

The agency has stated that all issues relating to the use of respirators for protection against occupational exposure to TB will be considered as a part of the TB rulemaking process. In the interim, until a final TB standard has been issued, areas where respiratory protection would be required must follow 29 CFR 1910.139. The employer remains responsible for the establishment and maintenance of a respiratory protection program.

If you have any additional questions or if we can be of any further assistance please do not hesitate to contact the [Office of Health Enforcement at (202) 693-2190].

[This document was edited on 2/4/2004 to strike information that no longer reflects current OSHA policy. On 12/31/2003 29 CFR 1910.139 was revoked and the 1997 proposed standard on Occupational Exposure to Tuberculosis (TB) was withdrawn in the Federal Register.]