Loose-fitting respirators do not require fit testing. Fit testing is required for all tight-fitting respirators, both supplied-air respirators and air-purifying respirators. The OSHA respiratory protection standard, 29CFR1910.134, requires fit testing prior to initial use, when there are changes, and annually. There are two methods of fit testing, qualitative and quantitative. OSHA-accepted protocols for qualitative fit testing (QLFT) and quantitative fit testing (QNFT) are found in 29CFR1910.134 Appendix A.
This Colden Tech Talk will clarify when each of these methods is acceptable for the most common types of respirators used in industrial plants: tight-fitting, air-purifying respirators. This group includes: filtering facepiece, half mask, full facepiece, and powered-air purifying respirators (PAPRs). This discussion does NOT include voluntary use of respirators, supplied air respirators, or pressure-demand (SCBA) respirators. When thinking about what type of fit testing is required, it is helpful to further divide this group between positive pressure respirators and negative pressure respirators.
Tight-fitting, Negative Pressure, Air-Purifying Respirators
|
Type |
Details |
APF |
Acceptable Fit Tests |
|
|
Qual. |
Quant. |
|||
|
Filtering facepiece |
NIOSH approved |
10 |
Yes |
Yes |
|
Half mask |
Contaminant concentration ≤ 10 X PEL** |
10 |
Yes |
Yes |
|
Full facepiece |
Contaminant concentration ≤ 10 X PEL** |
50 |
Yes |
Yes |
|
Full facepiece |
Contaminant concentration ˃ 10 X PEL** |
50 |
No |
Yes |
* APF – Assigned protection factor
** PEL – Permissible exposure level
Tight-fitting, Positive Pressure, Air-Purifying Respirators
|
Type |
Details |
APF |
Acceptable Fit Tests |
|
|
Qual. |
Quant. |
|||
|
PAPR |
Half facepiece |
50 |
Yes |
Yes |
|
PAPR |
Full facepiece |
1000 |
Yes |
Yes |
|
PAPR |
Helmet / hood |
25 |
Yes |
Yes |
|
PAPR |
Helmet / hood |
1000* |
Yes |
Yes |
*Manufacturer demonstrates this level of protection.
The tables above show that either a qualitative or quantitative fit test is acceptable for fit testing tight-fitting respirators. Pretty straight forward; just two items that lead to confusion: first, the idea that filtering facepiece respirators, commonly called “dust masks” need to be fit tested, and second, why full-face respirators sometimes must be quantitatively fit tested.
Filtering Facepiece Respirators
Filtering facepiece respirators are often misused (e.g. for solvent vapor exposures) and considered just a “dust mask” for nuisance dusts or comfort. NIOSH-approved filtering facepiece respirators have an APF of 10. Used correctly in the right context, single-use, air-purifying, NIOSH-approved, filtering facepiece respirators, can be a valuable addition to your respiratory protection offerings for protection against particulate inhalation exposures. They are often less onerous than elastomer facepiece respirators resulting in greater acceptance by workers.
Like all tight-fitting respirators, filtering facepiece respirators require fit testing and seal tests. How do you fit test a filtering facepiece respirator? The same way you would a halfmask or full facepiece. The photos below show filtering facepiece respirators being qualitatively fit tested and quantitatively fit tested. Vendors of fit testing equipment should be consulted for guidance.
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QNFT Filtering Facepiece Respirator Copyright 2012 TSI Incorporated, Used with permission |
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QLFT Filtering Facepiece Respirator |
Full Facepiece Respirators
Full facepiece respirators need to be quantitatively fit tested when used in environments where the contaminant concentration exceeds ten times the permissible exposure limit. This requirement relates to the term fit factor used by OSHA to describe how well a respirator fits. The fit factor is the ratio of contaminant outside the respirator compared to inside. Because with a QLFT the concentrations are not known, an estimated fit factor is given. The fit factor for passing all QLFT protocols is 100. In the Federal Register OSHA explains, “This limitation is based on the fact that the existing evidence only validates the use of qualitative fit testing to identify users who pass the QLFT with a respirator that achieves a minimum fit factor of 100.”
If a respirator fits well, it is thought to provide at least as much protection as the assigned protection factor (APF) for that class of respirators, plus a safety factor of 10. So a filtering facepiece respirator or half mask requires a fit factor of 100, and the full-face respirator requires a fit factor of 500. Because the top fit factor available for qualitatively fit testing a respirator is 100, the full-face respirator must be quantitatively fit tested in order to get a fit factor of 500. OSHA therefore allows QLFT only where the exposure concentration is less than ten times the permissible exposure limit (PEL).
QLFT may only be used to fit test negative pressure air-purifying respirators that must achieve a fit factor of 100 or less.
If the fit factor, as determined through an OSHA-accepted QNFT protocol, is equal to or greater than 100 for tight-fitting half facepieces, or equal to or greater than 500 for tight-fitting full facepieces, the QNFT has been passed with that respirator.
Seal Checking vs. Fit Testing
One final thought on fit testing, don’t confuse a fit test with a seal check. The fit test is a method used to select the right size respirator for the user. The seal check is a method to verify that the user has correctly put on the respirator and adjusted it to fit properly. A seal check must be performed each time an employee dons a tight-fitting respirator. Seal check procedures are found in Appendix B-1 of the OSHA respirator standard and provided by the respirator manufacturers.
For all tight-fitting respirators, the employer shall ensure that employees perform a user seal check each time they put on the respirator using the procedures in that the employer demonstrates are as effective as those in Appendix B-1 of this section.