RECORD ID
D00-06-001
STANDARD NUMBER
INFORMATION DATE
06-14-2000
SUBJECT
Respirator Protection Factors-practices
QUESTION
Response Line Question: The following is a request for clarification pertaining to respirator protection factors. It is commonly understood that a respirator protection factor should not be exceeded. This is derived from ANSI-Z-88.2, ?Practices for Respiratory Protection.?
When the airborne contaminant is radioactive material, is the limit based on not exceeding the Derived Airborne Concentration (DAC), i.e., 1 DAC inside the mask or is it exposure based and equivalent to 2000 DAC-hours? If a site has an administrative control level of 300 mrem, which converts to 120 DAC-hours, then their ACL is used in lieu of the 2000 DAC-hour limit.
For example, if an individual's respirator has a protection factor of 50 (APR) and the airborne radioactivity concentration is estimated to go as high as 100 DAC, may the contractor set a continuous air monitor to 100 DAC-hours and allow work to occur? In this scenarios, the contractor has exercised reasonable engineering controls to minimized airborne radioactivity and still believes that the PF will be exceeded. In this scenarios, it is also assumed that an ALARA evaluation may determine that the APR is a better selection than a respirator with a higher PF as well.
A similar scenario could occur for several types of respirators as well, including a bubble suit with a higher PF but yet, in spite of using engineering controls, may be exceeded.
If a CAM is set above the PF, may the contractor use the ratio of the CAM setpoint and PF to administratively track exposure and then correct the exposure based on actual results? May the results of DAC-hour tracking inside a bubble suit and/or bioassay be used to "de-assign" the number of DAC-hours or once the DAC-hours are recorded, must they be assigned?
If bioassay is less sensitive than the other monitoring methods (i.e., DAC-hour tracking)for a particular radionuclide (e.g., Ac-227) do you recommend against using the bioassay result?
REGULATORY REVIEW
The response to the question concerning applicable limits on respirator protection factors for radiological protection purposes will be issued in a Radiological Control Technical Position (RCTP). Issuing the RCTP will provide greater distribution of the information. You will be sent a copy of the RCTP. The below is in response to the remaining questions.
Applicable Requirements
10 CFR 835.209 Concentrations of radioactive material in air.
(b)The estimation of internal dose shall be based on bioassay data rather than air
concentration values unless bioassay data are:
(1) unavailable;
(2) inadequate; or
(3) internal dose estimates based on air concentration values are demonstrated to be as or more accurate.
Response
In response to the question concerning using the ratio of the CAM setpoint and assigned protection factor; values of air concentration (e.g. air sample results or CAM results) may be used in conjunction with a respiratory protection device's protection factor to administratively track exposures.
When a combination of bioassay and air concentration values are obtained, the bioassay data shall be used unless they are inadequate; or internal dose estimates based on air concentration values are demonstrated to be as or more accurate. Typically air monitoring results taken inside of a bubble suit would be considered to be more accurate than use of air monitoring data obtained outside the suit with application of the suit's assigned protection factor.
There are situations where there is a technology shortfall (i.e. available bioassay is not capable of detecting doses of 100 millirem) and workplace indicators, such as tracking of exposures to derived air concentrations (DAC-hr), determine that internal doses of 100 millirem or greater in a year are likely. For these situations, use of air concentration data, which is representative of the air the worker breathed, may be more appropriate for assessing internal dose than use of bioassay results which indicate no detectable activity. For example, air concentration values indicating a 40 DAC-hour exposure (100 millirem) should be considered for assessing internal dose if subsequent negative bioassay results are obtained which are only capable of detecting exposures in excess of 100 millirem.
Initiating timely special bioassay, e.g. fecal bioassay shortly after working in a plutonium environment with a respirator, may be helpful in significantly lowering the sensitivity of detection of internal exposures with bioassay. The timely special bioassay may provide adequate basis for determining internal exposures with bioassay results rather than with DAC-hour tracking results.