This is another part of my recent respirator articles; my attempt to help up-and-coming program administrators understand what OSHA is actually requiring as the absolute minimums. This post is about the “numbers” we see and hear when discussing respiratory protection. As I posted a few months ago, during an audit for a client, we came across emergency responders who had been fit-tested using Quantitative Fit Testing (QNFT) for an SCBA and “passed” with a Fit Factor well below 500. This was a serious error, but how many actually understand where the Fit Factor of 500 for a Full Face Respirator comes from? Well, here is what OSHA has to say about the Assigned Protection Factors, Fit Factors, and the “Safety Factor” when developing, implementing, and managing a respiratory protection program….
This first requirement is almost never cited by OSHA and I can not seem to get a sound answer from any acting OSHA CSHO’s as to why not. I know how my team of former OSHA CSHO’s and AD’s answer it and how we enforce it during our audits!
1910.134(f)(6) limits qualitative fit testing to situations where the user of a negative pressure air-purifying respirators must achieve a minimum fit factor of 100 OR LESS. 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. Dividing the fit factor of 100 by a standard safety factor of 10 means that a negative pressure air-purifying respirator fit tested by QLFT cannot be relied upon to reduce exposures by more than a protection factor of 10 (e.g., the APF for a half mask APR). The safety factor of 10 is used because protection factors in the workplace tend to be much lower than the fit factors achieved during fit testing; the use of a safety factor is a standard practice supported by most experts to offset this limitation.
For example, the ANSI Z88.2–1992 standard states, in clause 9.1.1,
"If a quantitative fit test is used, a fit factor that is at least 10 times greater than the assigned protection factor (table 1) of a negative-pressure respirator shall be obtained before that respirator is assigned to an individual. If a qualitative test is used, only validated protocols are acceptable. The test shall be designed to assess fit factors 10 times greater than the assigned protection factor."
1910.134(f)(7) lists the MINIMUM FIT FACTORS required to be achieved during QUANTITATIVE FIT TESTING. Half masks are required to achieve a minimum fit factor of 100 during QNFT, and full facepiece respirators must achieve a minimum fit factor of 500.
The safety factor of 10 used for full facepiece respirators is the same as that for half masks.
The minimum fit factors for QNFT are identical to the minimum fit factors required in OSHA substance-specific standards that require QNFT (See e.g., Asbestos, 29 CFR 1910.1001; Cadmium, 29 CFR 1910.1027; Benzene, 29 CFR 1910.1028; Formaldehyde, 29 CFR 1910.1048; 1,3-Butadiene, 29 CFR 1910.1051).
The results of the fit test MUST be AT or ABOVE the minimum fit factor required for that class of tight-fitting air-purifying respirator. The required fit factors are established by applying a safety factor of 10 to the for that class of respirator. For example, quarter and half mask air-purifying respirators with an Assigned Protection Factor (APF) of 10 must achieve at least a fit factor of 100, and full facepiece air-purifying respirators with an APF of 50 require a minimum fit factor of 500.