Health Physics Questions and Answers - Question 452
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 licensee facility.
(b) Yes. See NUREG-0041, Section 18.104.22.168, 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)