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A QLFT involves the introduction of an aero- worker well enough to satisfy the respira-
sol challenge agent into the area around the
face of the respirator wearer. OSHA require-
ments for fit-testing of respiratory protection
are spelled out under the third sentence of 29
CFR 1910.134(e)(5):*
“Training shall provide... an opportunity
to handle the respirator, have it fitted
properly, test its face-piece-to-face seal,
wear it in normal air for a long familiarity
period, and, finally, to wear it in a test
atmosphere.”
Protection Factors and QNFT/QLFT:
Half-mask respirators (including disposable
or filtering facepiece and replaceable filters)
have typically received an assigned protection
factor (APF) of 10 by ANSI and NIOSH. For
a QNFT, one uses the APF plus an assigned
minimum safety factor of 10 to establish the
“fit factor (FF).” The FF is what the wearer of
that respirator is assigned for the respirator
with which he/she was tested. For a dispos-
able respirator or half-mask respirator, based
upon the APF times the safety factor, one
must achieve a minimum FF of 100 in a
QNFT. [Note: the safety factor of 10 was cho-
sen based upon standard practice to help en-
sure adequate protection during field use;
ANSI Z88.2-1992 also recommends a safety
factor of 10]. OSHA has not formally as-
signed an APF to the Type 95, 99, or 100 res-
pirators certified under 42 CFR Part 84. As
you know, OSHA issued a proposed respira-
tory protection standard in the Federal Regis-
ter on November 15th, 1994 (Vol. 59, No.
219). When the final respiratory protection
standard is issued, the Agency will take a for-
mal position on the APFs. In the interim,
when the Type 95, 99, or 100 respirators are
quantitatively fit tested, OSHA will continue
to require a minimum FF of 100 in order for
the employer to conclude that they fit the
* 29 CFR 1910.134 is now codified for protection against TB as 29 CFR 1910.139.
94
tory protection standard.
In the 1994 CDC Tuberculosis Guidelines
where respiratory protection for occupational
exposure to Tuberculosis is addressed, the
CDC spelled out standard performance crite-
ria for half mask respirators. One point un-
der the criteria stated the following:
“The ability to be qualitatively or quanti-
tatively fit tested in a reliable way to ob-
tain a face-seal leakage of < 10%.”
This statement apparently has been misinter-
preted by some to imply that the new classes
of half mask respirators must only meet an in-
dividual FF of 10 rather than a FF of 100.
Until assigned protection factors are deter-
mined for these respirators, for those facilities
conducting QNFT, OSHA continues to re-
quire minimum fit factors of 100 to be ob-
tained.
Qualitative Fit-Testing Procedures:
For facilities electing to conduct QLFTs, a de-
termination of adequate fit is based upon
whether or not the individual can smell, taste
or detect the challenge agent. OSHA will ac-
cept those tests using the following challenge
agents currently available: irritant fume, sac-
charin or Bitrex™ aerosol. When an indi-
vidual passes a QLFT, a minimum FF of 100
will be assumed to have been achieved.
A number of queries to OSHA have involved
concerns regarding the use of irritant smoke
or saccharin aerosol QLFT protocols. Re-
cently, a peer reviewed article discussed the
validation of an alternative qualitative fit test-
ing media. That test media used is a sub-
stance called Bitrex (denatonium benzoate).
TM
This test and the testing protocols are de-
scribed in: