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Re: Appropriate Use of Respirator Protection Factors

It's my understanding that you don't multiply protection factors.  Although we
(HP's) often divide the concentration outside the respirator by the Assigned
Protection Factor to determine a concentration inside the respirator,
respirators don't really work that way.  The smallest APF should be used to
calculate a protection "threshold" concentration for the respirator.

Craig Reed
Oak Ridge, TN

Martin_Haas@notes.ymp.gov wrote:

> 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