U.S. Nuclear Regulatory Commission
Question 452: The following questions refer to the
selection and use of a half-mask face piece, as described
in Appendix A, "Protection Factors for Respirators":
a. Footnote "g" of Appendix A states that "this type of
respirator is not satisfactory for use where it might be
possible (e.g., if an accident or emergency were to occur)
for ambient airborne concentrations to reach instantaneous
values greater than 10 times the pertinent values in table
1, column 3 of Appendix B...," i.e., the derived air
concentrations (DACs) for inhalation. Is this provision
intended to apply to the work activity in progress for
which the respirator is being used, or is it more broadly
applicable to the type of facility or licensed activity?
For example, is the statement intended to exclude the use
of a half-mask face piece respirator at a nuclear power
plant? We believe that the use of half-mask face piece
respirators should be permitted with the same limitations
as are applied to other respirator types because the use of
a half-mask face piece may offer advantages over, for
example, a full face piece respirator in some applications
by keeping the overall total effective dose equivalent
ALARA. This would appear to be in keeping with the intent
of §20.1703, Use of Individual Respiratory Protection
Equipment, which states that ". . . the licensee may select
respiratory protection equipment with a lower protection
factor only if such a selection would result in keeping the
total effective dose equivalent ALARA."
b. Footnote "g" requires that ". . . the mask is to be
tested for fit prior to use each time it is donned . . ."
for the use of half-mask face pieces. Is a negative
pressure test an acceptable method to adequately test the
respirator prior to use? Such a qualitative test method
would seem to be acceptable because it appears that there
would be no practical method to accomplish a quantitative
test in the field prior to each use.
(a) This provision is intended to apply to situations in
which the ambient airborne concentrations are likely ". . .
to reach instantaneous values greater than 10 times the
pertinent values in table 1, column 3 of appendix B . . ."
The statement is not intended to exclude the use of a
half-mask face piece at a nuclear power plant or other
(b) Yes. See NUREG-0041, Section 126.96.36.199, for four
acceptable testing methods for field testing of respirator
operation (isoamyl acetate, irritant smoke, negative
pressure test, and positive pressure test). (Reference: 10
CFR 20, Appendix A).