U.S. Nuclear Regulatory Commission

Updated Guidance on Fit Testing of Biopak 60-P Respirator Users

HPPOS-146 PDR-9111210387

Title: Updated Guidance on Fit Testing of Biopak 60-P

Respirator Users

See the memorandum from L. J. Cunningham to J. N. Grace

(and others) dated August 19, 1984. It is acceptable to

check the fit of the Biopak 60-P while the user is wearing

just the facepiece equipped with a high efficiency filter

supplied by the manufacturer of the device. A fit factor

of 1000 is reasonable in the negative pressure

air-purifying mode. This memo supersedes an earlier one

from L. J. Cunningham to L. R. Greger dated August 8, 1983.

Licensees and inspectors had inquired as to what

constitutes an acceptable method for performing

quantitative fitting of the wearers of this apparatus as

required in footnote 1, to Appendix A of Part 20.

Specifically, was it acceptable to check the fit of the

device (the face to facepiece sealing capability) by

testing the user while the user was wearing just the

facepiece equipped with a high efficiency filter supplied

by the manufacturer of the device?

Previous guidance stated that the wearer must don the

entire unit for fit testing since it was felt that fitting

the facepiece with a high efficiency filter that is capable

of allowing no more than 0.03% leakage would preclude

measurement of the required 0.02% leakage or less through

the face to facepiece sealing area. However, the 0.03%

leakage allowed for high efficiency filters is determined

with a more penetrating aerosol (monodispersed) than used

in fit testing. Therefore, it is possible to measure the

0.02% leakage accurately with the facepiece equipped with a

high efficiency filter (0.02% leakage corresponds to a fit

factor of 5000).

Requiring a fit factor of 5000 in the negative pressure

air-purifying mode is too restrictive. This approach to

fit testing allows no credit for protection provided by the

positive pressure inside the facepiece generated by the

device in its normal mode of operation. Positive pressure

inside the facepiece can compensate for inward leakage of

contaminants to some extent by ensuring air circulating

through the device is leaked outward instead of leaking

contaminants into the worker's breathing zone. However,

with this device, protection is obtained at a large cost if

the fit is poor and outward leakage is substantial because

reduced service life results as outward leakage of air is

made up from the small volume of oxygen carried by the

user. The volume carried is sufficient to exchange the

volume of carbon dioxide released in respiration with

compressed oxygen. Carbon dioxide is removed from the

circulating air by the sorbent scrubber.

A hard and fast number that delineates good from poorly

fitting respirators is not available. In the opinion of

many experts in the field of respiratory protection, a fit

factor of 1000 seems reasonable for distinguishing between

good and poorly fitting respirators. It is recommended

that licensees use this number as a guide for determining

if an acceptable fit has been achieved with this device.

For those persons who are unable to attain a fit factor of

1000 with just the facepiece in negative pressure mode,

participation in emergency, potentially IDLH situations

should be restricted. This person may experience

drastically reduced service time which reduces emergency

response capability as well as hindering escape from a

potentially life threatening situation.

The intent of the previous guidance was not to verify

proper functioning of the entire unit. The operability of

the assembled unit is checked after maintenance and before

each use. In addition, fit testing of workers wearing the

assembled unit in the case of this apparatus was presenting

other problems due to the low makeup volume and leakage

detection interference from background water vapor droplets

and particulates from the carbon dioxide scrubber system.

Based on the interference problem that has been reported

and reevaluation of the previous guidance, it is

recommended that fit testing of wearers of the BioPak 60-P

be performed with just the facepiece equipped with a high

efficiency filter and that a factor of 1000 be considered

an acceptable fit. A recommendation will be made to RES to

update Appendix A to include the intent of this

interpretation in the next rule change.

Regulatory references: 10 CFR 20.103, 10 CFR 20.1703,

Regulatory Guide 8.15

Subject codes: 7.2, 8.10

Applicability: All