Appropriate Use of Respirator Protection Factors

[Martin_Haas@notes.ymp.gov]

This question relates to the proper interpretation of 10CFR20, Appendix A,
specifically, the table of allowed protection factors for respirators.
Part III of the same table notes that for use of any combination of
air-purifying and atmosphere-supplying respirators,  the protection factor
should be the same as for, " - - - type and mode of operation as listed
above".   My interpretation of this is that only a single protection factor
for combined use of respirators is allowed.  That is, one may not simply
multiply the protection factor for each of the respirators to obtain the
net multiplicative effect.   Consequently, the maximum protection factor
allowed is 10,000, [SCBA, full facepiece, PD] regardless of how respirators
are combined.

Others have the opinion that this is not the case; that in fact, use of two
different types of respirators in combination permits multiplying
protection factors of each in order to obtain a net effective protection
factor.

Your opinions are welcome either on-line or direct off-line to me at:
martin_haas@notes.ymp.gov