Dust Masks

[K P Steinmeyer <kpstein@gyral.com>]

Mike McDonald had two questions on my recent posting to Radsafe.

1.  How would a facility perform quantitative fit testing on these
filtering facepieces, if a true quantitative fit test is required?

Response.  NRC has never required quantitative fit testing (QNFT).  However
the currently available qualitative fit test (QLFT) methods are only
capable of showing a fit factor of 100.  Qualitative fit test methods are
really quasi quantitative, since the test subject's detection threshold is
established as part of the protocol, and the facepiece challenge
concentration is 100 times the sensitivity screening concentration.  Since
NRC is considering requiring a fit factor of 10 times the APF for
negative-pressure devices, a fit factor of only 100 would be able to be
demonstrated by QLFT.  Therefore QLFT could only be used for half facepiece
respirators, or an APF of no more than 10 could be taken even for full
facepiece negative pressure respirators.  NRC is considering allowing the
following QLFT methods: sodium saccharine, Bittrex, and irritant smoke.
All of these are described in the appendices to 29 CFR 1910.134.

2.  Will the manufacturers be producing a fit testing model, one with a
sample port manufactured into the facepiece?

Response.  3M provides a Q-version of their Model 8233 (N-100) and their
Model 8293 (P-100) only.  Check with other manufacturers for availability
of probed versions of their filtering facepieces.

K. Paul Steinmeyer

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