Respirator fit testing

Responding is Stephanie Lynch, CSP, senior research and technology manager, OHD, Hoover, AL.

If you’re at the point of needing to implement respirator fit testing, then you should have already assessed and quantified the inhalation hazard(s) present and identified the type of respirator(s) your employees will need to use.

Respirator selection is based on the level of protection you need to provide. Respirators in the United States have an assigned protection factor set by OSHA, which is outlined in Table 1 of CFR 1910.134. OSHA also outlines the process for how to use the APF based on the hazard level as it relates to a permissible exposure limit. Several respirator selection guides are available from other sources as well, such as NIOSH and respirator manufacturers.

There are two categories of respirator fit testing: qualitative and quantitative. Qualitative fit testing is a subjective pass/fail test, and a passed QLFT is assigned a fit factor of 100. QLFT can only be used to fit-test respirators that require a reference passing fit factor of 100 or less. This is typically half-face respirators – both elastomeric and filtering facepiece.

Quantitative fit testing measures actual leakage into a respirator using specialized equipment and provides a fit factor representing the fit. QNFT can be used for any required reference passing fit factor. There’s controlled negative pressure QNFT that uses pressure and air to challenge the respirator, and condensation nuclei counting QNFT that uses aerosols in the ambient air to challenge the respirator. CNP can be used anywhere but only on respirators with an elastomeric facepiece. CNC can be used on any respirator but has environmental requirements to ensure there’s enough aerosol in the air to be counted.

Clearly, respirator selection can help identify the fit-testing method appropriate for you, as some limitations for respirator fit-testing technologies are based on the respirator type. For instance, CNP QNFT wouldn’t be appropriate for the testing of filtering facepiece respirators. Other factors include the time it takes to perform each fit test and budget. QLFT takes significantly longer than QNFT but costs significantly less. The time and money you may be willing to contribute are also, of course, in part dependent on the number of employees you need to fit. If you have a lot of employees needing to be fit-tested, then this increases the value of the time saved by QNFT. You also need to consider where you’ll do your fit testing (designated area or multiple sites). Also, is it you performing the testing, or do you want to outsource fit testing to a contractor?

Respirator fit testing is only one of several requirements laid out by OSHA for the use of respiratory protection in the workplace. One of the best things you can do to effectively implement fit testing is to carefully read the regulation. This can help you test for and recognize competence for assigning a program administrator and selecting a respirator fit tester.

Editor's note: This article represents the independent views of the author and should not be considered a National Safety Council endorsement.