Re: Appropriate Use of Respirator Protection Factors

[Craig Reed <jreed@utk.edu>]

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
ETTP RADCON
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