NUREG/CR-0041 

Revision 1

Manual of Respiratory 

Protection Against 

Airborne Radioactive 

Material 

Radiation Safety Associates, Inc. 

U.S. Nuclear Regulatory Commission 

Office of Nuclear Reactor Regulation 

Washington, DC 20555-0001
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NUREG/CR-0041 

Revision 1 

Manual of Respiratory 

Protection Against 

Airborne Radioactive 

Material 

Manuscript Completed: December 2000 

Date Published: January 2001 

Prepared by 

K. Paul Steinmeyer 

Radiation Safety Associates, Inc. 

19 Pendleton Drive, P.O. Box 107 

Hebron, CT 06248 

NRC Technical Monitors 

A.K. Roecklein 

S. Sherbini 

J.E. Wigginton 

Prepared for 

Division of Regulatory Improvement Programs 

Office of Nuclear Reactor Regulation 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

NRC Job Code J2660
ABSTRACT 

This Manual provides information to assist respirator users and program staff in establishing a 

respiratory protection program that is in compliance with NRC regulations. It may also be of use to 

managers, supervisors, engineers and workers who may need to understand respirators, their uses, 

and their limitations. Chapter 1 provides a brief history of respirator regulations and discusses the 

applicability of OSHA's respiratory protection rules at an NRC-licensed facility. Chapter 2 covers 

evaluations to determine whether or not the use of respirators results in doses that are as low as 

reasonably achievable, and factoring hazards other than radiological hazards into decision making. 

Chapter 3 addresses respiratory protection procedures and programs, while Chapter 4 gives extensive 

information on respirators and related equipment including care, use and storage of this equipment. 

Chapter 5 offers advice on user-related issues such as medical evaluation, training and fit testing. 

Finally, Chapter 6 supplies information about personnel safety issues that may be related to 

respiratory protection, and addresses both radiological and non-radiological topics. A list of 

references and resources is included at the end of each chapter, which also provides e-mail 

addresses for various sources of information. 

Appendices describe the human respiratory system, particle collection mechanisms, a method for 

calculating effective protection factors for supplied-air respirators in a tritium environment, forms 

for medical screening and for reporting medical status, and a copy of the "Rainbow Passage" for use 

during fit testing. 

Front matter includes a list of acronyms and abbreviations, a list of NRC circulars, bulletins and 

notices related to respiratory protection, and a list of outdated NRC guidance documents on this 

topic.

iii
CONTENTS 

A b strac t ................................................................................................................................................. iii 

Table of Contents .................................................................................................................................... v 

List of Appendices .............................................................................................................................. xi. 

List of Figures ........................................ . . ............................................... xv 

L ist o f T ab le s ..................................................................................................................................... x v ii 

F o re w o rd .............................................................................................................................................. x iX 

Acknowledgements .............................................................................................................................. xxi 

Acronym s and Abbreviations .......................................................................................................... xxiii 

NRC Respirator-Related Circulars, Bulletins, and Notices ................................................................ xxv 

Outdated NRC Guidance ................................................................................................................. xxvii 

1. INTRODUCTION ............................................................................................................................. 1 

1.1 History of Respirator Regulation .................................................................................................. I 

Federal Laws .............................................. ........... I 

Federal Regulations ...................................................................................................................... I 

Regulatory Guide 8.15 ......................... .................... ..... 2 

NUREG-0041 .................................................... ..... 2 

AN SI Standards ............................................................................................................................ 2 

1.2 Applicability of OSHA 's Respiratory Protection Rules ......................................................... 2 

References and Resources .............................................................................................................. 4 

2. ALARA REQUIREM ENT ............................................................................................................ 5 

2 .1 In tro d u ctio n ......................................................................................................................................... 5 

2.2 ALARA Evaluation ............................................................................................................................ 5 

2.3 Estimating ALARA Benefit ..................................................................................................... 5 

2.4 Techniques for Limiting Respirator Use ........... ........................ . ......... 6 

2.5 Exam ples of ALARA Dose Estimations ..... ................... .................................. .... 6 

2.6 ALARA Evaluation-Records ....................................... ...... 8 

2.7 Exceptions to Respirator-ALARA Requirement ..................................................................... 8 

2.8 Respirator-Induced Inefficiency ............ ....... ............ . ............................. .. 9 

2.9 Dose Estimation ............................ . ..................... ..... 9 

References and Resources ......................... . . ... . ................... 10 

3. PROCEDURES AND PROGRAM S ............................................................................................. 11 

3.1 W ritten Procedures ........................................................................................................................... 11 

3.2 Separate Policy Statement Not Required .............................................................................. 11 

3.3 Evaluation of Use of Process or Other Engineering Controls .............................................. 11 

3.4 Use of Solvents for Decontam ination ..................................................................................... 12 

3.5 Respirator Selection .................................................................................................................... 12 

3.5.1 Prerequisites ...................................................................................................................... 12 

3.5.2 Selection (APF) ................................................................................................................. 13 

3.6 Application of Assigned Protection Factors .............................................................................. 13 

3.6.1 M eaning of Assigned Protection Factor (APF) ............................................................ 13 

3.6.2 Estimating Dose W hen Using Respirators .................................................................. 14 

3.6.3 Use of APFs Greater Than Part 20 Appendix A Values .............................................. 14 

v NUREG/CR-0041, Revision I
3.7 Qualifications of Program Personnel .......................................................................................... 14 

3.7.1 The Respirator Program Administrator (RPA) ........................................................... 14 

3.7.2 Technical Support Personnel ........................................................................................ 15 

3.7.3 Staying Abreast of New Developments ....................................................................... 15 

3.8 Appropriate Uses of Respirators ................................................................................................ 15 

3.8.1 W hen Indicated by ALARA Evaluation ....................................................................... 15 

3.8.2 For Emergency Entry into an Unassessed Environment ............................................. 15 

3.8.3 During the Initial Phase of an Operation .................................................................... 16 

3.8.4 W hile Process or Engineering Controls are Being Implemented ................................ 16 

3.8.5 W here a Professional Judgment M andates Such Use .................................................. 17 

3.9 Inappropriate Uses of Respirators ........................................................................................ 17 

3.9.1 Unjustifiable W ork in Atmospheres IDLH .................................................................. 17 

3.9.2 Compensation for Poor W ork Practices ...................................................................... 17 

3.9.3 Eye Protection Only ...................................................................................................... 17 

3.9.4 Surface Contamination Levels .................................................................................... 17 

3.10 Airborne Particle Production ............................................................................................... 17 

References and Resources ................................................................................................................ 19 

Associations and Organizations ................................................................................................. 19 

W e b S ite s .......................................................................................................................................... 2 0 

4. EQUI EPM ENT ........................................................................................................................................ 21 

4 .1 In tro d u ctio n ....................................................................................................................................... 2 1 

4.2 The Respiratory Inlet Covering ............................................................................................. 21 

4.2.1 Tight-Fitting Facepieces ............................................................................................. 22 

4.2.2 Loose-Fitting Facepieces ............................................................................................. 22 

4 .2 .3 H o o d s ................................................................................................................................ 2 2 

4 .2 .4 H e lm ets ............................................................................................................................. 2 3 

4 .2 .5 S u its .................................................................................................................................. 2 3 

4.3 Classification of Respirators ................................................................................................. 24 

4.4 Negative-Pressure Air-Purifying Respirators (APRs) ........................................................... 24 

4.4.1 Negative-Pressure Devices--General ........................................................................ 24 

4.4.2 Quarter-Facepiece Respirators, Negative Pressure M ode ........................................... 27 

4.4.3 Half-Facepiece Respirators--General ......................................................................... 27 

4.4.4 Dust M asks, Negative Pressure M ode ......................................................................... 27 

4.4.5 Half-Facepiece Respirators, Negative Pressure M ode ................................................ 28 

4.4.6 Full-Facepiece Respirators, Negative Pressure M ode ................................................ 28 

4.4.7 Advantages and Limitations of Negative Pressure Air-Purifying Respirators ............ 29 

4.5 Powered Air-Purifying Respirators (PAPRs) ....................................................................... 30 

4 .5 .1 G e n e ra l .............................................................................................................................. 3 0 

4.5.2 Advantages and Limitations of Positive Pressure Air-Purifying Respirators ............. 31 

4.5.3 Respirator Filters ....................................................................................................... 31 

NIOSH Regulations .................................................................................................... 31 

H E P A F ilte rs ................................................................................................................... 3 3 

Limitations of Respirator Filters ............................................................................... 34 

NUREG/CR-0041, Revision 1 vi
4.6 Supplied-Air Respirators (SARs) ......................................................................................... 34 

4 .6 .1 G e n e ra l .................................................................................................................................... 3 4 

4.6.2 Demand M ode Supplied-Air Respirators (Negative Pressure) .................................... 34 

4.6.3 Advantages and Limitations of Negative Pressure, Demand, Supplied-Air Respirators .35 

4.6.4 Constant Flow M ode (CF) ............................................................................................ 35 

4.6.5 Advantages and Limitations of Supplied-Air-Respirators ......................................... 36 

4.6.6 Pressure-Demand M ode ............................................................................................. 36 

4.6.7 Advantages and Limitations of Pressure-Demand, Supplied-Air Respirators ............. 39 

4.7 Self-Contained Breathing Apparatus (SCBA) ....................................................................... 39 

4 .7 .1 In tro d u ctio n ....................................................................................................................... 3 9 

4.7.2 Open-Circuit, Pressure-Demand SCBA ....................................................................... 39 

4.7.3 Advantages and Limitations of Open-Circuit Pressure-Demand SCBA ..................... 40 

4.7.4 Open-Circuit SCBAs with a Donning Switch .............................................................. 40 

4.7.5 Closed-Circuit Positive Pressure M ode ...................................................................... 41 

4.7.6 Advantages and Limitations of Full Facepiece, 

Closed-Circuit, Recirculating Positive-Pressure SCBA ............................................. 42 

4.8 Combination Devices ....................................................................................................................... 42 

4.8.1 Air-Purify ing/Supplied-Air ......................................................................................... 42 

4.8.2 Supplied-Air/Short-Duration SCBA ........................................................................... 43 

4.8.3 Supplied-Air/SCBA ..................................................................................................... 43 

4.8.4 NIOSH Certification .................................................................................................... 44 

4.8.5 Assigned Protection Factor ......................................................................................... 44 

4.9 The Role of NIOSH in Respirator Programs ............................................................................ 44 

4.9.1 Assigned Protection Factors (APF) .............................................................................. 44 

4.9.2 The NIOSH Approval Process .................................................................................... 45 

4.9.3 Approval of Combination Devices .............................................................................. 46 

4.9.4 W hat NIOSH Does Not Approve ................................................................................ 47 

4.9.5 Proper Use and M aintenance of Approved Devices .................................................. 47 

4.9.6 Form, Fit or Function .................................................................................................. 48 

4.9.7 Other W ays in W hich Devices M ight Be M isused ..................................................... 49 

4 .9 .8 C o n c lu sio n ......................................................................................................................... 4 9 

4 .9 .9 In p ut to N IO S H ................................................................................................................. 5 0 

4.10 Non-NIOSH-Certified Equipment ................................................................................................. 50 

4.10.1 Exemptions for Non-NIOSH-Certified Devices ............................................................ 50 

4.10.2 Radioiodine Canisters ............................................................................................... 50 

4.10.3 Supplied-Air Suits ........................................................................................................... 51 

4.10.4 Past Use of Uncertified Devices ...................................................................................... 51 

4.11 Inventory, Inspection, and Storage ........................................................................................... 51 

4 .1 1.1 F acep iece s ............................................................................................................................. 5 1 

4.11.2 Associated Equipment ................................................................................................ 52 

4.11.3 Emergency-Use SCBA .............................................................................................. 53 

4.11.4 SCBA Cylinders .............................................................................................................. 53 

4.11.5 Equipment in Storage ................................................................................................ 54 

4 .1 1.6 S h e lf L ife ......................................................................................................................... 5 4 

vii NUREG/CR-0041, Revision 1
4.12 Maintenance Program ....................... ........................... 56 

4 .12 .1 P u rp o se ............................................................................................................................ 5 6 

4.12.2 Qualifications of Respirator Maintenance and Repair Personnel .............................. 56 

4.12.3 SCBA Maintenance and Repair ............................... ............. 56 

4.12.4 Facepiece Leak T ests ...................................................................................................... 56 

4.12.5 T esting R espirator Filters ............................................................................................... 57 

4.12.6 R euse of R espirator Filters ............................................................................................... 57 

4.12.7 Equipm ent Calibration ..... . .... . . ...... . . ................................. 57 

4 .13 Q uality A ssurance .................................................................................................................... 5 7 

4.13.1 Purpose ...................... ...... .................... .............. 57 

4.13.2 N ew Equipm ent ........................................................................................................ 58 

F a c e p iec e s ....................................................................................................................... 5 8 

Cartridges, Canisters and Filters ................................... ... 58 

Pow ered A ir-Purifying Respirators ........................................................................... 58 

H o o d s an d S u its ............................................................................................................... 5 8 

R e g u lato rs ........................................................................................................................ 5 8 

C o m p re sso rs .................................................................................................................... 5 8 

A irlin e H o se .................................................................................................................... 5 9 

O pen-C ircu it S C B A ......................................................................................................... 59 

Closed-Circuit SCBA ....................................................... 59 

4.13.3 SCBA Inspection ................................................ 

4.13.4 Inspection and Tests After Cleaning and Maintenance .............................................. 60 

4 .14 C o ntro l and Issuance ................................................................................................................ 6 0 

4.15 Recordkeeping ......................... ......................................................... 60 

4.16 Respirators Supplied by Contractors ................. ...................... 60 

4.17 Service Life Lim itations ... ........ . . . . ................................. 61 

4.18 Breathing-A ir Supply and D istribution ............................................................................... 61 

4 .18 .1 S upp ly Sy stem s ............................................................................................................... 6 1 

4.18.2 D istribution Equipm ent ............................................................................................. 62 

4.18.3 Air Supplied to High-Pressure Breathing-Air Cylinders ...................... 64 

4.18.4 Problems with Breathing-Air System Contamination .............................................. 64 

4.19 Emergency Entry and Escape Equipment (IDLH) ................................................................... 65 

4.19.1 Equipm ent for Em ergency Entry ................................................................................ 65 

4.19.2 Equipm ent for Em ergency Escape ...................................... . .. ............ . ...... 65 

4.20 Potential Respirator Program W eaknesses .............................................................................. 65 

4.21 Decontamination and Sanitization of Facepieces; Contamination Control ........................ 66 

4.21.1 Introduction ................... ....................... 66 

4.21.2 Elastom eric and Plastic Com ponents ............................................................................... 66 

4 .2 1.3 SC B A C ylinders ........................................................................................................... . . 67 

4.21.4 Radiological G uidelines for Reuse ................................................................................. 67 

4.21.5 Radiological Guidelines for Reissue ........................................................... 68 

R eferences and R esources ................................................................................................................ 69 

NUREG/CR-0041, Revision I viii
5. R ESPIR A TO R U SER S ........................................................................................................................ 71 

5.1 M edical Evaluation ..................................................................................................................... 71 

5.1.1 The Licensee's Physician ............................................................................................. 71 

5.1.2 Establishing and Perform ing the Evaluation ................................................................ 72 

5.1.3 Psychological Factors ......................................................................................................... 72 

5.1.4 Tim ing of M edical Evaluations .................................................................................. 73 

5.1.5 Failure to M eet the A cceptance Criteria .................................................................... 73 

5.1.6 A pproval by Other Physicians ..................................................................................... 74 

5.1.7 Privacy of M edical Records ......................................................................................... 74 

5.1.8 M edical Status Form s .................................................................................................. 74 

5.2 Training ............................................................................................................................................. 74 

5.2.1 Q ualifications of Training Personnel ........................................................................... 74 

5.2.2 Contents of Training Program ..................................................................................... 74 

5.2.3 Effective Respirator Training ....................................................................................... 75 

5.2.4 Training for Supervisors of Respirator U sers .............................................................. 77 

5.3 Fit Testing ......................................................................................................................................... 77 

5.3.1 Introduction ............................................................................................................................. 77 

5.3.2 Relationship Betw een Fit Testing and Training .............................................................. 77 

5.4 Q uantitative Fit Testing (QN FT) ................................................................................................ 78 

5.5 Q ualitative Fit Testing (Q LFT) .................................................................................................. 79 

5.5.1 Capabilities and Lim itations of Q LFT ............................................................................... 79 

5.5.2 Irritant Sm oke ......................................................................................................................... 79 

5.6 Fit Test Protocols and Procedures ............................................................................................... 80 

5.6.1 Pre-Test Considerations ............................................................................................... 80 

5.6.2 The Protocol ...................................................................................................................... 80 

5.6.3 The Exercises .................................................................................................................... 80 

5.6.4 D uration of Exercises .................................................................................................. 82 

5.6.5 A cceptable Fit ................................................................................................................... 83 

5.7 Retesting ............................................................................................................................................ 83 

5.8 M inim um A cceptable QN FT Fit Factors .............................................................................. 84 

5.9 Sanitizing Respirators after U se In Fit Testing .................................................................... 84 

5.10 Com m unication ........................................................................................................................ 85 

5.10.1 N eed for Voice-A m plification Equipm ent ................................................................ 85 

5.10.2 Respirator Manufacturer-Supplied Equipment ............................ 85 

5.10.3 N on-Respirator M anufacturer-Supplied Equipm ent ................................................ 85 

5.10.4 O ther O ptions .................................................................................................................. 85 

5.11 V ision and V ision Correction .................................................................................................... 86 

5.12 U se of Respirators in Low Tem peratures ................................................................................. 86 

5.12.1 Lens Fogging ................................................................................................................... 86 

5.12.2 Exhalation V alve Freezing ......................................................................................... 87 

5.13 W earer Com fort and A cceptance ........................................................................................ 87 

References and Resources ................................................................................................................ 88 

ix NUREG/CR-0041, Revision I
6. SAFETY ................................................................................................................................................. 89 

6.1 Face-to-Facepiece Seal Integrity .................................................................................................. 89 

6.2 Standby Rescue Persons ................................................................................................................... 89 

6.3 Un-Assessed Environm ents ........................................................................................................ 90 

6.4 Em ergency Escape ........................................................................................................................... 90 

6.5 Breathing A ir .................................................................................................................................... 91 

6.5.1 Breathing-A ir System s .................................................................................................. 91 

6.5.2 Breathing-A ir Quality .................................................................................................. 91 

6.5.3 M oisture Content in Breathing-A ir Cylinders ............................................................. 91 

6.5.4 Testing Frequency ............................................................................................................. 91 

6.5.5 Test M ethods ..................................................................................................................... 92 

6.5.6 Sam pling Breathing A ir for Radiological Contam ination ........................................... 92 

6.5.7 Oxygen Purity Requirem ents ...................................................................................... 92 

6.6 Use of Higher or Lower APFs ................................................................................................... 92 

6.7 Lim iting Duration of Respirator Use ......................................................................................... 93 

6.7.1 Introduction ............................................................................................................................. 93 

6.7.2 Establishing Tim e Lim its ............................................................................................. 94 

6.7.3 Variables ................................................................................................................................. 95 

6.8 O SHA Requirem ents ....................................................................................................................... 95 

6.9 Radiological Hazard Evaluation ........................................................................................... 95 

6.9.1 A ir sam pling ..................................................................................................................... 95 

6.9.2 N oble Gases ...................................................................................................................... 95 

6.9.3 Tritium Vapors .................................................................................................................. 95 

6.10 N on-Radiological Hazard Evaluation ...................................................................................... 96 

6.10.1 Physical Stresses ............................................................................................................. 96 

6.10.2 Increased Breathing Resistance ...................................................................................... 97 

6.10.3 Increased Dead-A ir Volum e ........................................................................................... 98 

6.10.4 Additional W eight and Size ............................................................................................ 98 

6.10.5 Lim ited M obility ................................................................................................................... 99 

6.10.6 Psychological Distress .................................................................................................... 99 

6.11 High-Tem perature W ork Areas (Heat Stress) ............................................................................... 99 

6.11.1 Heat-Related Disorders ................................................................................................. 100 

6.11.2 Evaluation of Heat Stress .............................................................................................. 101 

6.11.3 Com plicating Factors .................................................................................................... 104 

6.11.4 Reducing Heat Stress .................................................................................................... 105 

Engineering Controls ..................................................................................................... 105 

Personal Protection ........................................................................................................ 106 

Adm inistrative Controls ................................................................................................ 106 

General Counterm easures .............................................................................................. 107 

6.12 Toxic and N uisance Atm ospheres .......................................................................................... 108 

6.12.1 Com m on Toxic Gases and Vapors at N uclear Facilities .............................................. 108 

6.12.2 Inert Gases .................................................................................................................... 110 

NUREG/CR-0041, Revision 1 x
6.13 Oxygen-Deficient Environments ................................................................................................. 112 

6.13.1 Oxygen Deficiency ........................................................................................................ 112 

6.13.2 Causes of Oxygen-Deficient Environments .................................................................. 112 

Reduction of the Percent Oxygen by Volume ............................................................... 112 

Reduced Atmospheric Pressure ..................................................................................... 113 

Comparisons- Reduced Atmospheric Pressure ............................................................ 114 

6.13.3 Oxygen Deficiency Immediately Dangerous to Life or Health (IDLH) ....................... 114 

D efin ition of ID L H ........................................................................................................ 114 

C o n fi n ed S p ace .............................................................................................................. 1 15 

IDLH--0 2 Concentration Less Than 12.5% Sea-Level Equivalent ............................. 116 

IDLH- Atmospheric Pressure Less Than 8.6 psia (450 mm Hg) ................................. 116 

0 2- IDLH at NRC-Licensed Facilities ......................................................................... 116 

M isinformation About IDLH ......................................................................................... 117 

6.13.4 Oxygen Deficiency Non-IDLH ..................................................................................... 117 

Non-IDLH---Confined Spaces ....................................................................................... 117 

Non-IDLH- Reduced Percent 02 ................................................................................ 117 

Non-IDLH- Reduced Atmospheric Pressure ............................................................... 117 

6.13.5 Entry into an IDLH Environment .................................................................................. 118 

6.13.6 Entry into a Reduced-Pressure Reactor Containment Building .................................... 119 

6 .13.7 C onfi ned Spaces ............................................................................................................ 120 

6.14 Use of Respirators by Non-Licensee Personnel .......................................................................... 121 

F irefig h ters ......................................................................................... 12 1 

D iv e rs ............................................................................................... 12 1 

Other Contractors ................................................................................. 121 

References and Resources .............................................................................................................. 122 

xi NUREG/CR-0041, Revision 1
Appendices 

A The Hum an Respiratory System and Particle Collection M echanism s ........................................ A-I 

Extrathoracic (ET) Region ....................................................................................................... A-I 

Bronchial (BB) Region .................................................................................................................. A-1 

Bronchiolar (bb) Region ........................................................................................................... A-I 

The Aveolar-Interstitial (AI) Region ........................................................................................ A-I 

Particle Deposition in the Lung ..................................................................................................... A-3 

Small Particle Collection- Brownian M otion .............................................................................. A-4 

Large Particle Collection- Impaction .......................................................................................... A-6 

Particle Size Sum mary ................................................................................................................... A-6 

Defense M echanism s of the Lung ................................................................................................. A-6 

References and Resources .................................................................................................................... A-8 

B Calculation of Effective Tritium Protection Factors for Supplied-Air Respirators ................. B-1 

C Respirator M edical Screening Questionnaire ........................................................................... C-1 

D Respirator User M edical Status Form ....................................................................................... D-1 

E The Rainbow Passage (For use during respirator fit testing) ..................................................... E-1 

F Oxygen Deficiency and the Relationship Between Percent 02 

and Elevation (Atm ospheric Pressure) ..................................................................................... F-1 

xiii NUREG/CR-0041, Revision I
Figures

Figure 4-1. Half-facepiece with replaceable cheek-mounted filter cartridges, 

and a full-facepiece with chin-mounted filter canister ................................................. 22 

Figure 4-2. Loose-fitting facepiece with a powered air-purifying device ....................................... 22 

Figure 4-3. Supplied-air hood, short shroud .................................................................................. 23 

Figure 4-4. Supplied-air hood, long shroud ..................................................................................... 23 

Figure 4-5. Supplied-air helm et ....................................................................................................... 24 

Figure 4-6. O ne-piece supplied-air suit ........................................................................................... 24 

Figure 4-7. Negative-pressure respirator operation ......................................................................... 26 

Figure 4-8. Full-facepiece with replaceable, cheek-mounted filters .............................................. 28 

Figure 4-9. Full-facepiece with replaceable, chin-mounted filter ................................................... 28 

Figure 4-10. Powered air-purifying respirator with full facepiece ................................................. 30 

Figure 4-11. Positive-pressure (PAPR) respirator operation .......................................................... 30 

Figure 4-12. Constant-flow supplied-air respirator with a full facepiece ....................................... 35 

Figure 4-13. Constant-flow respirator operation ............................................................................ 35 

Figure 4-14. Pressure-demand supplied-air respirator with full facepiece .................................... 38 

Figure 4-15. Pressure-demand respirator operation ....................................................................... 38 

Figure 4-16. Open-circuit, pressure-demand SCBA ...................................................................... 40 

Figure 4-17. Combination supplied-air respirator and air-purifying respirator .................................. 43 

Figure 4-18. Combination pressure-demand airline and short-duration SCBA .............................. 43 

Figure 4-19. Full-facepiece respirator with radioiodine canister attached ..................................... 51 

Figure 4-20. Typical breathing-air supply system ............................................................................... 62 

Figure 4-21. Recommended breathing-air distribution manifold configuration .................................. 63 

Figure 4-22. Self-contained 5-minute escape device ............................................................................. 65 

Figure 5-1. Positive-pressure and negative-pressure user seal checks ............................................ 75 

Figure 6-1. Sample collection design for a radiological sample of the breathing-air supply ...... 93 

Figure 6-2. NIOSH-recommended exposure limit (REL) for heat stress ........................................... 102 

Figure 6-3. Oxygen deficiency and the relationship between percent 02 and elevation (atmospheric 

pressure), after AN SI Z8.2- 1992, Table 2 ..................................................................... 115 

Figure A-1. The human respiratory system model, after ICRP Publication 66, 1994 ...................... A-2 

Figure A-2. Fractional deposition (%) of various size particles in each 

region of the respiratory tract for nose breathers ........................................................... A-4 

Figure A-3. Fraction deposition (%) of various size particles in each 

region of the respiratory tract for mouth breathers ................................................... A-5

XV NUREG/CR-0041, Revision I
Tables 

Table 4-1. Classification of respirators by type of respiratory inlet covering ................................. 25 

Table 4-2. Classification of respirators by source of breathing air ................................................ 25 

Table 4-3. Classification of respirators by mode of operation ....................................................... 26 

Table 4-4. Advantages and limitations of dust masks 

(negative-pressure, air-purifying respirators) ................................................................. 29 

Table 4-5. Advantages and limitations of half-facepieces 

(negative-pressure, air-purifying respirators) ................................................................. 29 

Table 4-6. Advantages and limitations of full-facepiece, negative-pressure, 

air-purifying respirators ................................................................................................ 29 

Table 4-7. Advantages and limitations of facepiece-type, positive-pressure, 

air-purifying respirators ................................................................................................ 32 

Table 4-8. Advantages and limitations of hood-type, positive-pressure, 

air-purifying respirators ................................................................................................ 32 

Table 4-9. Advantages and limitations of helmet-type, positive-pressure 

air-purifying respirators ................................................................................................ 32 

Table 4-10. New filter categories, 42 CFR 84 ................................................................................ 33 

Table 4-11. Advantages and limitations of facepiece-type, demand 

supplied-air respirators ................................................................................................ 35 

Table 4-12. Advantages and limitations of facepiece-type, constant-flow, 

supplied-air respirators ................................................................................................ 36 

Table 4-13. Advantages and limitations of hood-type, constant-flow, 

supplied-air respirators ................................................................................................ 37 

Table 4-14. Advantages and limitations of helmet-type, constant-flow, 

supplied-air respirators ................................................................................................ 37 

Table 4-15. Advantages and limitations of full-facepiece, pressure-demand, 

supplied-air respirators .................................................................................................. 38 

Table 4-16. Advantages and limitations of full-facepiece, open-circuit, 

pressure-dem and SC B A ............................................................................................... 4 1 

Table 4-17. Advantages and limitations of full-facepiece, closed-circuit, 

recirculating positive-pressure SCBA ........................................................................... 42 

Table 4-18. Particle removal efficiencies for various assigned protection factors ......................... 45 

Table 4-19. APFs for supplied-air respirators against tritium ......................................................... 45 

Table 4-20. N IO SH approval categories ........................................................................................ 46 

Table 4-21. Summary of recommended inspection frequencies for respiratory protection devices ........ 55 

Table 4-22. Recommended contamination guidelines for facepiece 

interiors prior to reissue ................................................................................................ 68

xvii NUREG/CR-0041, Revision 1
Table 5-1. Respirator APFs and required minimum fit factors ...................................................... 84 

Table 6-1. Partial pressures of the gases that com prise air ................................................................ 112 

Table 6-2. Oxygen partial pressure (mm Hg) at various altitudes .......................................................... 114 

Table A-1. Partial pressures of the various breathing gas constituents in inhaled air at sea level 

com pared to alveolar gas ....................................................................................................... A -3 

Table A-2. Fraction deposition (%) of various size particles in each region of the 

respiratory tract for nose breathers ........................................................................................ A -3 

Table A-3. Fractional deposition (%) of various size particles in each region of 

the respiratory tract for m outh breathers .......................................................................... A-5

NUREG/CR-0041, Revision 1 °°,i
FOREWORD 

This document, NUREG/CR-0041, Revision 1, "Manual of Respiratory Protection Against Airborne 

Radioactive Material," is issued as a technical supplement to the 1999 revision of Subpart H 

"Respiratory Protection and Controls to Restrict Internal Exposure In Restricted Areas" of 10 CFR 

20, and to Regulatory Guide 8.15, "Acceptable Programs for Respiratory Protection," Revision 1, 

October 1999. It imposes no new requirements. Rather, it is intended to provide licensees with 

technical assistance on establishing and administering programs, to provide licensees with the 

technical bases for industry good practices, offer suggestions for program content, and present facts 

about problems previously experienced in respiratory protection programs. References to existing 

sources of useful information are used extensively. 

The goal of every respiratory protection program is to protect the health of workers from injury 

caused by the inhalation of harmful materials, by exposure to inadequate oxygen concentration or 

poor quality breathing air, or by the inappropriate use of protective equipment. It is expected that the 

material provided in this Manual will contribute useful technical information to help achieve that 

goal.

xix NUREG/CR-0041, Revision I
ACKNOWLEDGEMENTS 

Material for this Manual was accumulated from many sources over many years. While the people 

who have contributed material or suggestions are too numerous to thank specifically here, they know 

who they are. Bob da Roza deserves special recognition for his assistance. Several other individuals 

reviewed portions of this material and shared their insights. They also have the author's thanks. 

Alan K. Roecklein, NRC project officer for this project, Sami Sherbini and James E. Wigginton, 

technical monitors, deserve a great deal of credit for the successful completion of this Manual. Their 

technical competence, thoroughness and knowledge of the regulatory arena contributed greatly to the 

quality of this Manual. 

Several of the drawings used were obtained from sites on the Internet, which are cited in the 

References and Resources section at the end of each chapter. Line drawings of equipment were 

solicited from all the respirator manufacturers listed in NIOSH's Certified Equipment List. Mine 

Safety Appliances Company of Pittsburgh, Pennsylvania was the only one who came through with 

useable material. While use of drawings of their equipment does not constitute a recommendation by 

NRC, we thank MSA for contributing to the information provided in this Manual. Finally, thanks to 

Kurt Newton for his assistance in creating and manipulating graphics, and to Sharyn Mathews, for 

editorial and manuscript production assistance.

xxi NUREG/CR-0041, Revision 1
ACRONYMS AND ABBREVIATIONS 

ACGIH American Conference of Governmental Industrial Hygienists 

AEC Atomic Energy Commission 

Al Alveolar interstitial region of the respiratory tract 

ALARA As low as is reasonably achievable 

ALI Annual limit on intake 

AMAD Activity median aerodynamic diameter 

ANSI American National Standards Institute 

APF Assigned protection factor 

APR Air-purifying respirator 

CDC Centers for Disease Control 

CDE Committed dose equivalent 

CEDE Committed effective dose equivalent 

CF Constant flow or continuous flow 

CFR Code of Federal Regulations 

CGA Compressed Gas Association 

DAC Derived air concentration 

DDE Deep dose equivalent 

DHHS Department of Health and Human Services 

DOE Department of Energy 

DOL Department of Labor 

DOP Dioctyl phthalate 

EMT Emergency medical technician 

EPA Environmental Protection Agency 

ERDA Energy Research and Development Administration 

FF Fit factor 

HEPA High-efficiency particulate air 

HHE Health hazard evaluation 

IDLH Immediately dangerous to life or health 

LPN Licensed practical nurse 

MMAD Mass median aerodynamic diameter 

MPC Maximum permissible concentration

xxiii NUREG/CR-0041, Revision I
MSHA Mine Safety and Health Administration 

NFPA National Fire Protection Association 

NIOSH National Institute for Occupational Safety and Health 

NP Negative pressure 

NRC Nuclear Regulatory Commission 

OSHA Occupational Safety and Health Administration 

PAPR Powered air-purifying respirator 

PC Protective clothing 

PD Pressure demand 

PEL Permissible exposure limit 

PP Positive pressure 

pp Partial pressure 

PPE Personal protective equipment 

QLFT Qualitative fit test 

QNFT Quantitative fit test 

RD Recirculating demand (closed-circuit SCBA) 

REL Recommended exposure limit 

RG Regulatory Guide 

RN Registered nurse 

RP Recirculating positive pressure (closed-circuit SCBA) 

RPA Respirator program administrator 

RPM Radiation protection manager 

SAR Supplied-air respirator 

SCBA Self-contained breathing apparatus 

SCUBA Self-contained underwater breathing apparatus 

SG Steam generator 

TC Tested and certified 

TEDE Total effective dose equivalent 

TLV Threshold limit value 

USP United States Pharmacopoeia 

WBGT Wet bulb globe temperature

NUREG/CR-0041, Revision 1 xxiv
NRC Respirator-Related Circulars, Bulletins and Notices 

Document 

Number Title Date 

78-03 Potential Explosive Gas Mixture Accumulations February 8, 1978 

Associated with BWR Offgas System Operations 

78-07 Protection Afforded by Air-Line Respirators and June 12, 1978 

Supplied-Air Hoods 

79-08 Interconnection of Contaminated Systems with March 28, 1979 

Service Air Systems Used as the Source of Breathing 

Air 

79-09 Occurrences of Split or Punctured Regulator June 22, 1979 

Diaphragms in Certain Self-Contained Breathing 

Apparatus 

79-15 Bursting of High Pressure Hose and Malfunction of August 8, 1979 

Relief Valve and "O"-Ring in Certain Self-Contained 

Breathing Apparatus 

80-03 Protection From Toxic Gas Hazards March 6, 1980 

80-19 NIOSH Recall of Recirculating-Mode (Closed May 6, 1980 

Circuit) Self-Contained Breathing Apparatus 

(Rebreather) 

81-26, PART 1 Use of Recirculating-Mode (Closed Circuit) Self- August 28, 1981 

Contained Breathing Apparatus (Rebreathers) 

81-26, PART 2 Use of the Chemical "DOP" August 28, 1981 

81-26, PART 3 Placement of Personnel Monitoring Devices for August 28, 1981 

External Radiation Exposure 

81-26, PART 4 Personnel Entry Into Inerted Containment August 28, 1981 

81-26, PART 5 Evaluation of Instrument Characteristics When Using August 28, 1981 

Portable Radiation Survey Instruments 

82-28 Hydrogen Explosion While Grinding in the Vicinity July 23, 1982 

of Drained and Open Reactor Coolant System 

82-36 Respirator Users Warning for Certain Five-Minute September 2, 1982 

Emergency Escape Self-Contained Breathing 

Apparatus 

83-21 Defective Emergency-Use Respirator April 15, 1983 

83-67 Emergency-Use Respirator Material Defect Causes October 11, 1983 

Production of Noxious Gases 

83-68 Respirator User Warning: Defective Self-Contained October 11, 1983 

Breathing Apparatus Air Cylinders 

84-24 Physical Qualification of Individuals to Use April 5, 1984 

Respiratory Protective Devices 

84-34 Respirator User Warning: Defective Self-Contained April 23, 1984 

Breathing Apparatus Air Cylinders 

84-56 Respirator Users Notice for Certain 5-Minute July 10, 1984 

Emergency Escape Self-Contained Breathing 

Apparatus

XXV NUREG/CR-0041, Revision I
Title

Failure of Air-Purifying Respirator Filter to Meet 

Efficiency Requirement

Date

August 6, 1984

85-06 Contamination of Breathing Air Systems January 23, 1985 

85-48 Respirator Users Notice: Defective Self-Contained June 19, 1985 

Breathing Apparatus Air Cylinders 

85-60 Defective Negative-Pressure, Air-Purifying, Full July 17, 1985 

Facepiece Respirators 

85-87 Hazards of Inerting Atmospheres November 18, 1985 

86-24 Respirator Users Notice: Increased Inspection April 11, 1986 

Frequency for Certain Self-Contained Breathing 

Apparatus Air Cylinders 

86-43 Problems with Silver Zeolite Sampling of Airborne June 10, 1986 

Radioiodine 

86-46 Improper Cleaning and Decontamination of June 12, 1986 

Respiratory Protection Equipment 86-103 Respirator Coupling Nut Assembly Failures December 16, 1986 

88-100 Memorandum of Understanding Between NRC and December 23, 1988 

OSHA Relating to NRC-Licensed Facilities (53 FR 

43950, October 31, 1988) 

89-47 Potential Problems With Worn or Distorted Hose May 18, 1989 

Clamps on Self-Contained Breathing Apparatus

Importance of Proper Response to Self-Identified 

Violations by Licensees

Recent Incidents Resulting in Offsite Contamination -I.

Issues Associated with Use of Strontium-89 and Other 

Beta Emitting Radiopharmaceuticals

Equipment Failures at Irradiator Facilities

DOT Safety Advisory: High Pressure Aluminum 

Seamless and Aluminum Composite Hoop-Wrapped 

Cylinders

Failure to Provide Special Lenses for Operators Using 

Respirator or Self-Contained Breathing Apparatus 

During Emergency Operations

Problems With Emergency Preparedness Respiratory 

Protection Programs

National Institute for Occupational Safety and Health 

Respirator User Notice: Special Precautions for 

Certain Self-Contained Breathing Apparatus Air 

Cylinders

January 12, 1990

March 3. 1994

September 29, 1994 

December 28, 1994 

January 4, 1995 

August 20, 1997 

June 3, 1998 

April 10, 2000

NUREG/CR-0041, Revision I

Document 

Number

0U-U01

94-16 

94-70

97-66

2000-07

Generic Communications 

The NRC does not provide a list of outdated communications in this category. Generic communications generally serve the purpose of alerting industry to some type of current problem, and are therefore not intended to be current forever. 

Licensees should refer to these documents for any useful information they may contain.

Date

84-60•

-

March 3, 1994

94-89P

95-01

9!8-20

xxvi

-- ,
Outdated NRC Guidance Documents

The health physics positions (HPPOS) and the answers provided in question and answer guidance 

(Q&A) listed below should no longer be used. The issues addressed have been affected by changes in 

the regulations, consensus standards and industry practices, and other documents. If the NRC staff 

updates the HPPOS data base, the affected documents will either be deleted or undergo significant 

revision. 

HPPOS 

94: Regulations now prohibit beards. Background information still pertinent. 

116: Same as 94 above. Technical rationale for not wearing facial hair is still valid, 

but regulations now prohibit beards. 

117: Regulations concerning medical screening have changed. Frequency may be a 

function of wearer's age. 

146: Regulations and guidance have changed for recirculating-mode SCBA. 

162: Note that Regulatory Guide 8.15 (Rev. 1) allows contact lens use. 

175: This is not completely consistent with upcoming guidance in ANSI-Z88.10 

"Respirator Fit Testing." 

219: The basic information is not incorrect, but licensees should refer to Section 5.1.3 

of Regulatory Guide 8.15 (Rev. 1). 

225: The old footnote (g) to 10 CFR 20 Appendix B established restrictions on the use 

of half-facepiece respirators. These restrictions have been removed. 

Q&As 

131: The requirement for users to perform a user seal check upon donning a face

sealing respirator now has updated references. 

386: Interim Policy Period is over; transition is complete. 

418: The parenthetical discussion note on OSHA medical approvals is not consistent 

with the 1999 revision to 10 CFR 20 Subpart H, which allows dust masks to be used 

on a voluntary basis (assuming no credit) with no medical screening or fit testing. 

See Regulatory Guide 8.15, Rev. 1, section 4.8.

xxvii NUREG/CR-0041, Revision 1
1 INTRODUCTION

1.1 History of Respirator Regulation 

Federal Laws 

The Atomic Energy Act of 1946 briefly 

acknowledged the potential peaceful benefits 

of atomic power. But it did not allow for 

private, commercial application of atomic 

energy. The act established the five-member 

Atomic Energy Commission (AEC) to 

manage the nation's atomic programs. 

In the Atomic Energy Act of 1954, the 

government ended its monopoly on technical 

data and made the growth of a private 

commercial nuclear industry an urgent 

national goal. The AEC was assigned to 

continue the weapons program, promote the 

private use of atomic energy for peaceful 

applications, and protect public health and 

safety from the hazards of commercial nuclear 

power. 

Congress passed the Energy Reorganization 

Act of 1974, which divided the AEC into: the 

Energy Research and Development 

Administration (ERDA) to manage the 

nuclear weapons, naval reactors, and energy 

development programs; and the Nuclear 

Regulatory Commission (NRC) to regulate the 

possession and use of byproduct, source, and 

special nuclear material. Finally, the 

Department of Energy Organization Act of 

1977 brought the federal government's 

energy-related agencies and programs into a 

single agency. The Department of Energy 

(DOE), activated on October 1, 1977, 

assumed the responsibilities of the Federal 

Energy Administration, the Energy Research 

and Development Administration, the Federal 

Power Commission, and parts and programs 

of several other agencies. The NRC continues 

to regulate byproduct, source and special 

nuclear material. NRC does not, and did not in

the past, regulate accelerator-produced 

radioactive materials or radiation-producing 

machines. NRC's regulations are contained in 

Title 10 of the Code of Federal Regulations. 

Federal Regulations 

Prior to 1994, the regulations contained in 

10 CFR 20.103 addressed respiratory 

protection program requirements and use of 

respirators, and limited internal doses 

resulting from radioactive materials indirectly 

by limiting the intakes (i.e., MPC-hours) 

independent of doses resulting from external 

doses. Initially the table of protection factors 

was included in Regulatory Guide 8.15 

"Acceptable Programs for Respiratory 

Protection," but was later incorporated into 

Appendix A of Part 20. Some additions and 

changes were made over the years to these 

respirator regulations, but the dose-limitation 

methodology only changed when the current 

version of 10 CFR 20 took effect in 1994. The 

1994 change requires that internal and 

external doses be combined into a single dose 

called total effective dose equivalent (TEDE). 

It also requires that ALARA principles be 

applied to this quantity rather than optimizing 

external and internal doses separately, as was 

the case in the older regulations. The program 

requirements (Subpart H and Appendix A to 

10 CFR 20) carried over into the "new" Part 

20 almost unchanged. Significant changes to 

Subpart H and Appendix A were made in 

1999. This NUREG provides a technical basis 

to support implementation of the 1999 

changes.

I NUREG/CR-0041, Revision 1
Regulatory Guide 8.15

The original Regulatory Guide 8.15, 

"Acceptable Programs for Respiratory 

Protection," was published in October 1976 

and remained unchanged until October 1999, 

when Revision 1 was published to support the 

1999 revision to 10 CFR 20 Subpart H and 

Appendix A. The NRC believes that the 

current rule, supported by guidance in 

Regulatory Guide 8.15, provides licensees 

with a great deal of flexibility in 

implementing a high-quality respiratory 

protection program. 

NUREG-0041 

The NRC issues documents called NUREGs 

for various purposes. NUREGs do not contain 

"new regulations" as the name might imply. 

Like regulatory guides, they do not contain 

any legally binding requirements. 

NUREG-0041 was published in 1976 in 

conjunction with Regulatory Guide 8.15. It 

was an excellent effort on the part of the 

authors and virtually all nuclear respiratory 

protection programs use it as a foundation, but 

since it is based on 1970s technology and 

practice, it has become less and less useful in 

recent years. 

Revision 1 to NUREG-0041 is intended to 

update the areas of interest identified in the 

original version, provide supplementary 

guidance in areas not covered in the original, 

and provide licensees with the benefit of 

experience gained in respiratory protection 

programs over the past 25 years.

These consensus standards, issued by the 

American National Standards Institute', 

contain specifications applicable to various 

aspects of a licensee's operation and are 

sometimes referenced in Federal Regulations 

and NRC Regulatory Guides. ANSI is a non

governmental independent organization, 

although government representatives sit on 

many of the committees. A consensus 

standard is one that is developed by interested 

parties. These include major respirator users, 

respirator manufacturers, government 

agencies, trade unions, military services, etc. 

Of particular interest here is ANSI Z88.2

1992, "Practices for Respiratory Protection." 

The NRC's position on this ANSI standard is 

contained in Regulatory Guide 8.15 

Revision 1. 

1.2 Applicability of OSHA's Respiratory 

Protection Rules 

There are four categories of hazards that may 

be associated with NRC-licensed facilities: 

"* Radiation risk produced by radioactive 

materials; 

"* Chemical risk produced by radioactive 

materials; 

"* Facility conditions that affect the safety of 

radioactive materials and thus present an 

increased radiation risk to workers. For 

example, these might produce a fire or an 

explosion, and thereby cause a release of 

radioactive material or an unsafe reactor 

condition; and 

"* Facility conditions that result in an 

occupational risk, but do not affect the 

safety of licensed radioactive materials. For 

example, there might be exposure to toxic 

non-radioactive materials and other 

industrial hazards in the workplace. 

S11 West 42' Street, New York, NY 10036. A 

complete list of ANSI Standards may be found at 

www. ANSI.org.

NUREG/CR-0041, Revision 1

A NSI Standards

2
Generally, the NRC has jurisdiction over the 

first three categories listed above, and OSHA 

has jurisdiction over the fourth hazard. Under 

the terms of the memorandum of understanding 

(MOU) that exists between the NRC and 

OSHA, the NRC reports to the licensee and to 

OSHA any observed violations in the fourth 

category. Likewise, OSHA will inform the 

appropriate NRC Regional Office of matters 

under the NRC's jurisdiction when they come 

to the attention of OSHA through complaints or 

inspections. 

The NRC does not conduct inspections focused 

on industrial safety in the course of inspections 

of radiological and nuclear safety, but NRC 

personnel may identify safety concerns within 

the area of OSHA responsibility, or may 

receive complaints from an employee about 

OSHA-covered working conditions. The NRC, 

however, does not make decisions regarding 

activities under the purview of OSHA. 

The NRC has made every effort to make the 

Subpart H program compatible with the 

OSHA program. Complying with OSHA 

program requirements will result in satisfying 

most of the NRC requirements, with the 

exception of those few differences specifically 

identified in Regulatory Guide 8.15, 

Revision 1, paragraph 6.8. The converse is not 

true, however. Complying only with NRC 

requirements will not satisfy all OSHA 

requirements because the NRC's program is a 

small subset of the OSHA program. The NRC 

believes that if a licensee implements a 

respiratory protection program that complies 

with 10 CFR 20 requirements, the program 

will be consistent with all applicable OSHA 

requirements. 

The NRC recognizes that most licensees 

generally experience very low levels of 

airborne radioactive material during normal 

operations, and that any need for a respiratory 

protection program would be dictated by the 

presence of airborne industrial contaminants. 

In this case, an OSHA program would be

needed rather than an NRC program. If an 

ALARA analysis results in a licensee decision 

that respirators would not be needed to limit 

the intake of airborne radioactive material, but 

respirators are assigned to protect against 

other industrial contaminants, then the 

presence of low levels of radioactive material 

could be considered incidental, and an OSHA 

program would be adequate to protect 

workers. It is important to note that even if a 

respiratory protection program is not required 

by the NRC, a licensee must still monitor for 

intake of radioactive material in accordance 

with 10 CFR 20.1502(b). Also, if a licensee is 

"taking credit" for the protection against 

airborne radioactive material even if the 

respirators are worn for industrial protection, 

then the licensee must also comply with the 

applicable Subpart H rules. 

Licensees should consider the need for 

establishing a respiratory protection program 

based on a prospective analysis of the 

potential for worker exposures to airborne 

radioactive material during normal operations 

and during credible abnormal occurrences. 

NRC regulations require that licensees use 

procedures and controls to achieve 

occupational doses that are ALARA. It would 

be a licensee decision, based on an ALARA 

analysis, whether or not to use respirators to 

reduce exposure even further. Other controls, 

such as limiting duration of exposure, are 

permitted. 

Licensees should also determine whether or 

not an emergency situation could reasonably 

be expected to arise that would require the use 

of respirators by facility workers responding 

to the emergency conditions. If so, then the 

licensee should establish an NRC-required 

respiratory protection program, and determine 

how extensive that program must be. The 

NRC staff believes that any respiratory 

protection program that meets Part 20 

requirements should provide a good basis for 

respiratory use in emergency situations.

3 NUREG/CR-0041, Revision 1
The assigned protection factors published by 

the NRC apply only in a respiratory protection 

program that meets the requirements of 10 

CFR 20, Subpart H. They are applicable only 

to airborne radiological hazards and may not 

be appropriate to circumstances when 

chemical or other respiratory hazards exist 

instead of, or in addition to, radioactive

hazards. Selection and use of respirators for 

such circumstances must comply with 

Department of Labor regulations. In the case 

where both radiological and non-radiological 

airborne hazards exist, primary consideration 

should be given to the more hazardous 

component.

References and Resources 

I. Department of Health and Human Services, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505-2888. Phone: 304-285-5907; Fax: 304-285-6030. 

2. Dooley, Lawrence M. and Francis L. Barresi. "Workers' Perception of Respirator Use and 

Internal Dose: A Humanist's Perspective." Radiation Protection Management, Vol. 11, No. 6 

(Nov./Dec. 1994), pp. 29-32. <http://www.radpro.com> 

3. U.S. Nuclear Regulatory Commission, Washington, DC 20555, <http://www.nrc.gov>.

NUREG/CR-0041, Revision I 4
2 ALARA REQUIREMENT

2.1 Introduction 

The term "respiratory protection" does not 

necessarily mean "use of respiratory protective 

devices." Engineering and work practice 

controls are generally regarded as the most 

effective methods to control exposure to 

airborne radioactive materials. The use of 

respirators is the least satisfactory method of 

respiratory protection because: 

"* Respirators provide adequate protection 

only if they are properly fitted (face

sealing devices); 

"* Respirators provide adequate protection 

only if they are properly worn; 

"* Respirators protect only the employees 

who are wearing them, rather than 

reducing or eliminating the hazard from 

the workplace as a whole (which is what 

engineering and work practice controls 

do); 

"* Respirators are generally uncomfortable to 

wear, cumbersome to use, and interfere 

with vision and communication in the 

workplace, which can often be critical to 

maintaining safety and health; and 

"* The costs of operating a compliant 

respiratory protection program are 

substantial - including regular medical 

examinations, fit testing, training, and the 

purchasing and maintaining of equipment. 

2.2 ALARA Evaluation 

The NRC does not intend that licensees develop 

a new ALARA program or procedures to 

address respirator use. Rather, respiratory 

protection-related ALARA considerations 

should be factored into the existing evaluation 

method as one more dose-related variable. The 

NRC intends that respirator-related ALARA 

requirements should be incorporated into the 

existing ALARA program. For example, if the

existing ALARA program requires that a check

list be completed during the processing of each 

radiation work permit to determine whether or 

not a formal ALARA review is needed, then 

factors that impact internal dose should be 

included on such a check-list. If the existing 

ALARA program requires that a formal 

ALARA evaluation be performed for a task if 

the anticipated collective dose might exceed 

I person-rem TEDE, the dose projection used in 

making this determination should include both 

internal and external dose. 

As part of an overall hazard evaluation process, 

licensees should include non-radiological 

factors when deciding if respirators should be 

used. Licensees should take into account 

potential unintended consequences of assigning 

a specific type of respirator. For example, 

assignment of a negative-pressure air-purifying 

respirator in a high-temperature, high-humidity 

work environment might have much more 

negative impact on overall worker safety than 

an incremental increase in external dose. 

2.3 Estimating ALARA Benefit 

An article entitled "Dose Expansion from Using 

Respirators"' provides information on methods 

that licensees may use in performing ALARA 

evaluations. While this article was written 

before the current revision of 10 CFR 20 

became effective and therefore, still uses the 

maximum permissible concentration (MPC) 

terminology, the principles presented are still 

valid. 

Licensees should take into account total risk to 

workers when establishing radiological controls 

for various tasks. An article, "Optimizing 

SGreenwood, Regis A. and Thomas J. O'Dou. "Dose 

Expansion from Using Respirators," Radiation 

Protection Management, Vol. 9, No. 4 (July/August 

1992), pp. 22-29.

5 NUREG/CR-0041, Revision I
Worker Protection: The Practical Application of 

Risk Analysis,"'2 illustrates the place of radiation 

dose within the larger framework of industrial 

safety. Consideration should be given to 

industrial safety concerns such as heat stress, 

which might be aggravated by the use of 

respirators, and the increased likelihood of 

industrial accidents when workers must climb 

ladders or work on scaffolding while wearing 

respirators. 

If the difference in a worker's TEDE between 

using or not using respirators is small, the 

decision to use or not use respirators should be 

based on other considerations since either 

option could be considered to be in the spirit of 

ALARA. At low DDE rates, respirator-induced 

inefficiency will have little impact on total dose 

estimations. 

2.4 Techniques for Limiting Respirator Use 

Listed here are some techniques that licensees 

might consider, to limit the use of respirators. 

"* Containment systems that prevent the 

release of radioactive material into the 

work environment; 

"* Use of filtered ventilation systems; 

"* Decontamination of the work area prior to 

work; 

"* Spraying areas or components with a 

water mist to prevent contamination from 

becoming airborne; and 

"* Using contamination fixatives such as 

strippable paint prior to work. 

2.5 Examples of ALARA Dose Estimations 

In the following examples, the subscript "w" 

indicates "with respirators." The subscript "1w/o" means "without respirators." Acronyms 

for dosimetry terms can be found in the List of

Acronyms and Abbreviations in the front of 

this Manual. 

CEDEw is estimated as follows: 

CEDEw,o 

APF 

Respirator-induced worker inefficiency is 

assumed to be 15% in all of these examples. 

Worker inefficiency caused by respirator use 

is covered in section 2.8 below. 

The percentage difference between CEDEw 

and CEDEw/o can be calculated as follows: 

(CEDEw/° -CEDEw) 1 0 0 

CEDEwo 

RPAs are reminded that these are only 

examples of TEDE estimations. No 

generalizations or decisions about a licensee's 

program should be made based on these 

specific examples. 

Example I1-High external dose rate and high 

airborne concentration 

The average airborne contamination 

concentration in a work area is estimated to be 

30 times the DAC for the mix of radionuclides 

present based on historical data. The deep

dose equivalent rate in the work area is 

200 mrem/h, and the job is projected to last for 

1 hour. 

Evaluation 1: Without respirators 

200 mrem 

DDEo - x I h = 200mrem 

h 

CEDEo = 30 DAC x lh x 2.5 mrem =75mrem 

DAC-h 

TEDEo = 275 mrem.

2 Williams, Michael C. "Optimizing Worker Protection: 

The Practical Application of Risk Analysis," Health 

Physics, Vol. 59 (1990), pp. 925-929.

NUREG/CR-0041, Revision I 6
Evaluation 1: with respirators

With full-facepiece respirators (APF = 100), 

using a 15% worker inefficiency factor: 

DDEw = 200mrem xl.15h=230mrem 

h 

CEDEw~ 30 DAC 2.5mrem - - x xl.15h• 1lmrem 

100 DAC-h 

TEDEW =231 mrem. 

The difference (275 - 231 = 44 mrem) is in 

favor of respirator use. The decision to NOT 

use respirators could be justified in this case if 

added worker stress is significant, or if other 

safety issues are involved. 

Example 2-High external dose rate and low 

airborne concentration 

The average airborne contamination 

concentration in a work area is estimated to be 

2 times the DAC for the mix of radionuclides 

present based on historical data. The deep

dose equivalent rate in the work area is 

180 mrem/h, and the job is projected to last 

4 hours. 

Evaluation 2: Without respirators 

180 mrem 

DDEw,o = x4h =720mrem 

h 

2.5 mrem CEDEWo = 2 DAC x 4 h × - = 20 mrem 

DAC - h 

TEDE ,o = 720 + 20 = 740 mrem.

With full-facepiece respirators (APF = 100), 

using a 15% worker inefficiency factor: 

180 mrem 

DDEW = 180 ×___ x4.6 h = 828 mrem 

h 

2 DAC 2.5mrem 

CEDE, =_- x4.6 h x 0.23mrem 

100 DAC - h 

TEDE, = 828 mrem. 

The difference (828 - 740 = 88 mrem) is in 

favor of no respirator use. Therefore, 

respirators should not be used unless there are 

other factors involved. 

Example 3-Low external dose rate and high 

airborne concentration 

The average airborne contamination 

concentration in a work area is estimated to be 

20 times DAC for the mix of radionuclides 

present based on historical data. The deep

dose equivalent rate in the work area is 

3 mrem/h. The job is projected to last 2 hours. 

Evaluation 3." without respirators 

3 mrem 

DDE ,.o = 3 ×_x 2 h = 6 mrem 

h 

CEDE wIo = 20 DAC x 2 h x 2 mrem 100 mrem 

DAC - h 

TEDEwtI = 106 mrem. 

Evaluation 3: with respirators 

With full facepiece respirators (APF + 100), 

using a 15% inefficiency factor: 

DDE =3mrem x2.3h =7mrem h 

20 DAC 2.5 mrem CEDEw = -- x2.3hx 1 lmrem 

100 DAC - h 

TEDEw 8 mrem.

NUREG/CR-0041, Revision I

Evaluation 2." with respirators

7
The difference (106 - 8 = 98 mrem) is in favor 

of respirator use. A reasonable judgment in 

this case would be that respirators should be 

used unless there are other safety factors 

involved. 

Example 4-Low external dose rate and low 

airborne concentration 

The average airborne contamination 

concentration in a work area is estimated to be 

2 times the effective DAC for the mix of 

radionuclides present based on historical data. 

The deep dose equivalent rate in the work area 

is 10 mrem/h. The job is projected to last 

2 hours. 

Evaluation 4." without respirators 

1 0 mrem 

DDEwo = h 2 h=20mrem h 

2.5 mrem 1 

CEDEw,o 2DACx2 hx -h= 10mrem 

TEDEw,o0 =30 mrem. 

Evaluation 4: with respirators 

With half-facepiece respirators (APF= 10), 

using a 15% inefficiency factor: 

DDE = 10 mrem x 2.3 h=23 mrem 

h 

CEDEW - 2 DAC x2.3h x 2.5 mrem -- =mrem 

(10) DAC-h 

TEDEW, 24mrem. 

Since there is no real difference in projected 

dose whether or not respirators are used, a 

reasonable judgment would be that respirators 

should not be used. 

2.6 ALARA Evaluation-Records 

For tasks that require a formal ALARA review, 

no additional documentation on the use or nonuse of respirators should be needed, as long as 

that review includes adequate information about 

how CEDE was considered. 

For tasks that do not require a formal ALARA 

review but where the work area contains 

airborne radioactivity to the extent that it is 

posted "Caution Airborne Radioactivity Area," 

then a record should be made that justifies the 

use or non-use of respirators for that job. A 

notation on a work document (e.g., a radiation 

work permit) is acceptable if it contains 

sufficient detail. Licensees might consider 

preparing a series of relatively generic 

justifications (based on historical information) 

for a variety of commonly encountered work 

situations. The work document could then 

simply reference the applicable justification. 

2.7 Exceptions to Respirator-ALARA 

Requirement 

Optimization of radiation dose is not the only 

test that should be applied in a radiological 

workplace. The concept of "worker safety" 

should also encompass consideration of hazards 

from falls or injuries due to tangling of airlines 

or use of bulky equipment, heat-related stress or 

illness, problems created by workers not being 

able to adequately communicate, and other 

problems that are caused by respirator use. The 

NRC intends to encourage licensee judgement 

in the decision to require the use of respirators 

where they may not be justified by an ALARA 

analysis, or to not use them when their use 

would reduce dose but decrease worker 

industrial safety. 

Listed below are a few valid considerations that 

the RPA may take into account that would 

suggest either that respirators should be worn 

even though the are not justified by an ALARA 

analysis, or that respirators should not be worn 

even though TEDE will be higher than if they 

were used: 

* Heat stress to workers. Some respirators 

provide body cooling that could mitigate an 

otherwise significant heat exposure.

NUREG/CR-0041, Revision I 8
Conversely, some types of respirators might 

make a heat stress situation worse; 

"* Type and quantity of protective clothing 

needed for a job. This could also have heat 

stress implications; 

"* Environmental conditions and how they 

might influence the decision to use or not 

use respirators; 

"* Skill and experience level of the workers 

involved; and 

"* Post-work consequences of not using 

respirators, such as the need for personal 

decontamination, skin-dose assessments, 

responding to portal monitor alarms, 

psychological strain on workers who are 

contaminated, and so on. 

2.8 Respirator-Induced Inefficiency 

It is widely recognized that the use of 

protective clothing, including respirators, 

generally reduces worker efficiency. 

Generally, the more complex the task, or the 

more coordination needed among respirator 

wearers, the greater the inefficiency. It should 

also be recognized that respirators are used in 

conjunction with protective clothing, which 

also contributes to worker inefficiency. Often, 

when higher levels of protective clothing are 

needed, more protective respirators are also 

used. A worker assigned to wear both cloth 

and plastic protective clothing will probably 

also use a supplied-air hood, both for 

respiratory protection and body cooling. The 

more-protective respirators often slow a 

worker down more than a less protective 

device. Worker efficiency can also be 

degraded significantly when the work 

environment is very cold, or is hot and humid. 

There are numerous other variables.

The NRC believes that use of an inefficiency 

factor of up to 15% is reasonable when 

respirators are worn. This factor may be used 

by licensees when making ALARA decisions 

on respirator use. Recognizing the numerous 

variables involved, however, licensees may 

use larger factors, but the licensee should have 

adequate justification.3 Such justification 

could consist of prior field experience, 

professional judgment, time-motion studies, 

mock-up exercises, or other sources. Licensees 

should reevaluate the inefficiency factor used 

as work progresses in the same way that 

protective clothing requirements might be 

reevaluated, and modify the inefficiency factor 

as appropriate. The NRC also recognizes that 

shifting from using respirators to not using 

respirators (or vice versa) part way through a 

job might not be cost-effective in terms of re

instructing workers, modifying work permits, 

or altering communications equipment 

requirements, etc., and therefore, might not be 

ALARA. Future evaluations of similar jobs, 

however, should benefit from the lessons 

learned. 

2.9 Dose Estimation 

The appropriate method for dose estimation is to 

determine the concentration actually breathed 

by the worker by dividing the average airborne 

concentration in the work area during the work 

period by the assigned protection factor of the 

respirator being used. This method is illustrated 

in Section 2.5. Bioassays may also be used to 

assess intakes, especially if relatively high 

intakes are a possibility, or if respirator failure is 

suspected. Bioassay measurements also provide 

an on-going evaluation of the effectiveness of 

the airborne radioactive material measurement 

and control program, as well as an evaluation of 

the effectiveness of the respiratory protection 

program. 

Lee, Roy. "The Effects of Respiratory Protection on 

Worker Efficiency." Radiation Protection Management. 

Vol. 1I, No. 5 (September/October 1994), pp. 28-42.

NUREG/CR-0041, Revision I 9
Radiation workers should not be subjected to radioactivity. Such practice might produce 

an excessive number of bioassay undue psychological stress on the workers. 

measurements to quantify minor intakes of 

References and Resources 

I. Kephart, Gary S. "Respiratory Protection and Worker Efficiency-A Review." Radiation 

Protection Management, Vol. 11, No. 4 (July/Aug 1994), pp. 70-74. <http://www.radpro.com> 

2. Greenwood, Regis A. and Thomas J. O'Dou. "Dose Expansion from Using Respirators." 

Radiation Protection Management, Vol. 9, No. 4 (July/Aug 1992), pp. 22-29. 

<http://www.radpro.com> 

3. Earley, Jack N. "Professional Suicide: Disregarding the Respiratory Protection Realities of the 

Revised 10 CFR 20." Radiation Protection Management, Vol. 9, No. 4 (July/Aug 1992), 

pp. 44-48. <http://www.radpro.com> 

4. Khan, T.A. and J.W. Baum. "Optimization of the Control of Contamination at Nuclear Power 

Plants." NUREG/CR-5038, BNL-NUREG-52073 (May 1988), U.S. Nuclear Regulatory 

Commission, p. 22. 

5. Raven, P.B., A.T. Dotson, and T.O. Davis. "The Psychologic Consequences of Wearing 

Industrial Respirators." American Industrial Hygiene Association Journal, Vol. 40 (June 1979), 

pp. 517-534. 

6. Nielson, R., A.R. Gwosdow, I.G. Berglund and A.B. Dubois. "The Effect of Temperature and 

Humidity Levels in a Protective Mask on User Acceptability During Exercise." American 

Industrial Hygiene Association Journal, Vol. 48 (July 1987), pp. 639-645. 

7. Merwin, S.E., J.A. MacLellan, M.F. Mullen, et al. "Regulatory Analysis of the Revision of 

10 CFR Part 20." PNL-6212, Pacific Northwest Laboratory, pp. 5.1. 

8. Cardarelli, R., K.L. Mossman, et al. "The Effect of Respiratory Protection on Worker 

Efficiency-ALARA Considerations." Health Physics, Vol. 50-Supplement 1 (June 1986), 

pp. $49-$50. 

9. James, R., F. Dukes-Dobos and R. Smith. American Industrial Hygiene Association Journal, 

Vol. 45 (June 1984), pp. 399-404. 

10. Johnson, A.T., C.M. Grove and R.A. Weiss. Respirator Performance Rating Tables for Non

Temperate Environments." American Industrial Hygiene Association Journal, Vol. 53 

(September 1992), pp. 548-555. 

11. Williams, Michael C. "Optimizing Worker Protection: The Practical Application of Risk Analysis," 

Health Physics, Vol. 59 (1990), pp. 925-929. 

12. Lee, Roy. "The Effects of Respiratory Protection on Worker Efficiency." Radiation Protection 

Management, Vol. 11, No. 5 (Sept/Oct 1994), pp. 28-42. <http://www.radpro.com> 

13. Electric Power Research Institute, "Effects of Respirators on Worker Efficiency." EPRI TR

105350, Final Report, June 1995.

NUREG/CR-0041, Revision I 10
3 PROCEDURES AND PROGRAMS

3.1 Written Procedures 

The NRC regulations supported by Regulatory 

Guide 8.15, Revision 1, specify the written 

procedures that are necessary in a respiratory 

protection program. Given here are a few 

suggestions for inclusion in those procedures. 

A program should be established that 

identifies those positions with supervisory and 

technical responsibilities in the respiratory 

protection program including the Respirator 

Program Administrator (RPA); specifies 

minimum training and retraining requirements 

for each position; and identifies the minimum 

qualifications for appointment or assignment 

to these positions. The radiological and non

radiological respiratory protection programs 

may have different Administrators, so long as 

adequate communication and coordination 

exists between the programs. (This is an 

exception to ANSI Z88.2-1992, paragraph 

4.5.1.) 

The job description of each position in the 

respirator program should include a minimum 

level of training and/or experience related 

directly to respiratory protection that a person 

should have prior to filling such a position. 

Recommendations for the contents of a 

respirator user-training program are contained 

in Chapter 5 of this Manual. This training 

should include the requirement for each 

respirator user to inspect the respirator prior to 

donning and to perform a user seal check each 

time a face-sealing respirator is donned. 

Written guidelines should be established that 

limit respirator-induced stresses on workers. 

First, each respirator wearer should be 

informed that (s)he may stop work and exit the 

work area at any time for relief from respirator 

use. This may be precipitated by equipment 

malfunction, physical or psychological

distress, procedural or communications 

failure, significant deterioration of operating 

conditions, or any other condition that might 

require such relief. This is commonly referred 

to as "self-determination." Second, procedural 

controls should be established that take into 

account environmental factors in the work 

place that might present a risk to respirator 

wearers. These time limitations do not 

necessarily have to be stated in terms of a 

specific maximum number of continuous 

hours, or hours in a day or in a week that a 

person may work in a respirator. Time 

limitations may be based on a heat stress 

assessment performed prior to or during 

specific jobs. More specific information is 

provided in Chapter 6 of this document. 

3.2 Separate Policy Statement Not Required 

Previous versions of the NRC's regulations 

required licensees to develop and promulgate 

a policy statement on respirator use. The 

policy statement committed licensees to the 

use of process or other engineering controls, 

instead of respirators; defined what was meant 

by routine, non-routine, and emergency use of 

respirators; and described the periods of 

respirator use and steps to be taken for relief 

from respirator use. While these commitments 

and issues need to be addressed in the 

licensee's respiratory protection program, they 

are to be included in the written procedures. 

No separate document (policy statement) 

needs to be produced or maintained. 

3.3 Evaluation of Use of Process or Other 

Engineering Controls 

During routine work activities, process or 

engineering controls should be implemented 

when practicable for most situations where 

otherwise respirators would have to be worn.

I1I NUREG/CR-0041, Revision 1
If workers are assigned to use respirators to 

perform routine tasks, the results of an 

evaluation should be available to show why 

engineering controls were not considered to be 

ALARA. 

In situations where respirators are used 

infrequently or in a non-routine manner, re

evaluations should be performed periodically 

to ensure that the engineering controls remain 

unwarranted. 

Areas where emergency situations have 

developed, or could reasonably be expected to 

develop, that would require respirator use 

should be identified. Consideration should be 

given to staging emergency-use respirators of 

the appropriate type(s) near these areas. 

All principles used in an ALARA evaluation, 

including cost, may be used in determining the 

reasonableness of implementing engineering 

controls for the reduction of airborne 

radioactivity. The evaluations and re

evaluations described above should be part of 

an on-going process. Procedures and 

programs should be formally reviewed 

periodically to ensure that they address the 

licensee's current situation. Documentation 

that such an evaluation has been performed 

could be an entry on a radiological work 

permit (RWP), or an entry in a logbook. 

3.4 Use of Solvents for Decontamination 

It is commonly believed that the use of solvents 

will cause surface contamination to become 

airborne as the solvent evaporates. Similarly, it 

is believed that if contaminated surfaces are 

wetted with water and heated, the water vapor 

will carry particulate contaminants into the air. 

Unless the radioactive contaminant is 

chemically bonded to the water or solvent 

molecule (e.g., T20), or unless the boiling point 

of the radioisotope is exceeded, none of the 

contamination will become airborne due to the 

evaporation of any of these liquids. Rapid 

evaporation (i.e., boiling) is the principle used in

radioactive liquid waste evaporators. If there 

were significant carry-over or volatilization of 

radioactive contaminants, such a system would 

not work. 

3.5 Respirator Selection 

3.5.1 Prerequisites 

Once a determination has been made that 

respirators are appropriate for a particular job, 

certain prerequisites should be satisfied. 

First, during non-emergency situations, use of 

respiratory protective devices is permitted 

only in atmospheres where the radiological 

hazards have been identified and assessed. If 

there is significant loose surface 

contamination in the work area, and the 

planned work activities are such that some 

significant fraction of the loose contamination 

is likely to become airborne, the estimated 

average potential concentration should also be 

considered when selecting the respirator for 

the job. Potential airborne contamination from 

specific work activities-such as opening the 

interiors of contaminated piping systems or 

ventilation systems-should also be 

considered when selecting respirators. 

Second, each respirator wearer must have been 

medically evaluated, trained, and fit-tested (for 

face-sealing devices), and the dates of these 

must be current. The respirators used must be 

NIOSH-approved or NRC-accepted devices, 

must have been inspected and sanitized since 

the device was last used, and must meet all the 

other criteria stated in 10 CFR 20 Subpart H. 

Third, non-radiological hazards and potential 

hazards that might exist in addition to 

radiological hazards should also be assessed. 

The respirator assigned should be adequate to 

protect the wearer from all such hazards. For 

example, air-purifying respirators do not 

supply air or oxygen and therefore may not be 

used in an area where airborne radioactivity 

occurs in conjunction with an oxygenNUREG/CR-0041, Revision I 12
deficient atmosphere. Oxygen deficiency is 

described in Chapter 6 of this document. 

3.5.2 Selection (APF) 

The assigned protection factor (APF) of the 

respirator selected for use during a particular 

job should be as high as practical to minimize 

internal dose, taking into account ALARA 

considerations and other factors. If the 

expenditure of resources needed to set up and 

use the device with the higher APF cannot be 

justified, or if the device with the higher APF 

would have a negative impact on overall 

worker safety or dose, or if another good 

reason exists, then a device with a smaller 

APF could be chosen. Examples of some work 

place conditions that might influence the 

selection of a specific type of respirator are: 

1. Temperature; 

2. Humidity; 

3. Ambient noise; 

4. Need for clear, precise communication; 

5. Entry into a confined space; 

6. Need to climb caged ladders; and 

7. Need for mobility. 

3.6 Application of Assigned Protection 

Factors 

3.6.1 Meaning of Assigned Protection 

Factor (APF) 

The assigned protection factor (APF) is not a 

measured value, but rather an assigned number 

for a type or class of respirators. The current 

APFs were set by the ANSI Z88.2-1992 

Committee. Data on the fit factors obtained 

with different types of respirators and the 

protection factors these respirators provided 

under actual working conditions were 

reviewed when available. The distributions of 

protection factors provided by these 

respirators under working conditions were 

then examined for each respirator type, and 

the 5'h percentile of these distributions 

calculated. The 5th percentile is the value of

the protection factor that is higher than 5% of 

the protection factors measured for that type of 

respirator under working conditions. Stated 

differently, 95% of the protection factors were 

higher than the 5 1h percentile values. These 5th 

percentile values were then assigned to the 

respective respirator types as the assigned 

protection factors (APFs). For cases where 

little or no working condition data was 

available, the APFs were selected by 

comparison and extrapolation from similar 

respirator types for which data was available. 

When the APF of a respirator is evaluated in 

relationship to the APFs of other devices, 

decisions can be made regarding the degree of 

protection afforded to the wearer by the 

respirator-the higher the APF, the greater the 

protection. The APF can be viewed as the 

minimum degree of protection the device 

should provide to a properly trained and fit

tested (for face-sealing devices) wearer, who is 

wearing and using the respirator properly, 

under normal conditions of use in the field. It 

is recognized that most devices will provide a 

higher degree of protection to most wearers 

than is indicated by the APF. 

APF should not be confused with the number 

obtained during quantitative respirator fit 

testing (QNFT). The number that results from 

quantitative fit testing is called a fit factor 

(FF). Minimum acceptable fit factors are often 

stated in terms of multiples of the APF (e.g., 

10 times the APF). Even though an individual 

achieves a Fit Factor of 1,000 or 3,000 during 

fit testing, credit may only be taken for the 

APF listed in Appendix A to 10 CFR 20 for 

the respirator type in question. Application can 

be made to the Commission for use of 

protection factors higher than the listed APFs.

13 NUREG/CR-0041, Revision I
3.6.2 Estimating Dose When Using 

Respirators 

Worker dose may be estimated by either of the 

following methods: 

A. Divide the measured concentration by the 

APF of the respirator used. Then divide 

this concentration by the applicable DAC 

to obtain the multiple of the DAC 

assumed to be breathed by the respirator 

wearer with credit taken for the APF of 

the device. The measured concentration 

should be as representative as possible of 

the average value of the airborne 

radioactive material concentration during 

the work period for which the dose is 

being estimated. This number, then, is the 

estimated number of DAC-hours of 

exposure accumulated by each respirator 

wearer during each clock-hour of 

exposure. See the example below. 

Example 

Given: Cmeaured = 3E-6 ptCi/mL; APF = 100; 

DAC = I E-8 jtCi/mL; and texposure = 4 h. 

Calculate DAC-hours of exposure. 

3 E- 6 p. Ci/mL = 3 DAC- h per clock hour 

(100)(1E-8 itCi/mL) 

3 DAC- h 4 clock hours x =12 DAC- h clock hour 

2.5 mrem 12 DAC - h x = 30mrem. 

DAC - h 

B. Perform bioassay to determine the 

quantity of radioactivity in the exposed 

person's body.

3.6.3 Use of APFs Greater than 

Part 20 Appendix A Values 

Licensees who perceive the need to use an 

APF for a device which is greater than that 

listed in Appendix A to 10 CFR 20 may apply 

to the Commission for permission to do so. 

This application should contain the following 

information: 

" Describe the situation for which the higher 

APF is needed; 

" Explain why other NIOSH-approved 

devices that have sufficiently high APFs 

are not suitable for the licensee's situation; 

and 

"* Demonstrate that the device is capable of 

providing the requested level of protection 

under the proposed conditions of use. 

Data submitted to demonstrate that higher 

protection factors can be achieved with the 

device may be developed by the manufacturer 

of the device, by the licensee, or by a suitably 

qualified and reliable third party. 

3.7 Qualifications of Program Personnel 

3.7.1 The Respirator Program 

Administrator (RPA) 

The RPA should have knowledge of 

respiratory protection topics sufficient to 

supervise the respiratory protection program 

properly. He or she should have the ability, training and experience to evaluate the total 

workplace hazard, recommend engineering 

controls if appropriate, specify respiratory 

protection if control cannot otherwise be 

obtained, and decide against the use of 

respirators if conditions warrant. No academic 

degree or professional certification is required.

NUREG/CR-0041, Revision 1 14
3.7.2 Technical Support Personnel 

Persons performing technical functions in a 

respirator program should have specific 

documented training in the area(s) in which 

they have duties. This should be a 

combination of classroom training and on-job 

training under supervision. These persons 

should demonstrate a sufficient level of 

knowledge and skill before they are permitted 

to perform these tasks unsupervised. Examples 

of these technical job functions are fit testing, 

training, maintenance and repair, quality 

assurance inspection and testing, equipment 

issue, equipment decontamination and the like. 

Certain maintenance jobs, such as work on 

SCBA regulators, require specialized training 

provided or certified by the equipment 

manufacturer. 

3.7.3 Staying Abreast of New Developments 

Since this Manual was first published in 1976, 

rapid advancements have occurred in the field 

of respiratory protection. It is important that 

the RPA and respirator program supervisors 

stay abreast of new developments such as 

advances in technology, current issues, and 

changes in regulations. This can be done by 

periodically attending lectures, seminars or 

training courses on the topic. Some other 

sources of information are: 

"* The Federal Register prints all changes in 

federal regulations, and various 

abstracting services identify changes to 

health and safety regulations. 

"* Health and safety professional societies, 

through their publications, keep members 

apprised of new developments. A few of 

these are the American Industrial Hygiene 

Association (AIHA), National Fire 

Protection Association (NFPA), American 

Society of Safety Engineers (ASSE), 

International Society for Respiratory 

Protection (ISRP), the American 

Conference of Governmental Industrial 

Hygienists (ACGIH), the National Safety 

Council (NSC), and the Health Physics

Society (HPS). Membership in one or 

more of these organizations is 

recommended for RPAs. Contact 

information is included in the References 

and Resources section at the end of this 

chapter. 

Publications from NIOSH, NRC, and 

OSHA often contain information on topics 

related to respirators and respiratory 

protection. 

3.8 Appropriate Uses of Respirators 

It is not the intention of the Commission to 

eliminate the use of respiratory protection 

devices by licensees, but to limit their use to 

those situations or occasions where it is 

justifiable based on an evaluation of the 

significant risks involved. The situations listed 

below are examples of times when the use of 

respirators is appropriate. This list may not be 

all-inclusive, but merely illustrates the types of 

situations where the use of respirators, at least 

in the initial phases of work, may be justified. 

3.8.1 When Indicated by ALARA 

Evaluation 

Respirators may be used when the results of 

an ALARA evaluation show that the use of 

respirators will save significant radiation dose 

and the increased risk from non-radiological 

hazards are outweighed by the radiological 

risk avoided by the dose reduction. 

3.8.2 For Emergency Entry into an 

Unassessed Environment 

Entry into an environment where the hazards 

have not been assessed presents some 

potentially serious problems. It is recognized 

that the TEDE from even a very high 

concentration of airborne radioactive material 

is unlikely to create an environment (from 

airborne hazards alone) that is immediately 

dangerous to life or health (IDLH) in case of

15 NUREG/CR-0041, Revision 1
respirator failure. However, two other very 

important factors should be considered before 

personnel are permitted to enter an unassessed 

environment. 

First, it should be established that concurrent 

non-radiological hazards do not exist that 

might jeopardize the life or health of 

individuals entering the area. If such a 

concurrent hazard exists or might exist (e.g., 

confined space, oxygen-deficiency, poisonous 

or toxic gas), additional steps have to be taken 

in accordance with the applicable regulations, 

to ensure the safety of the entering personnel. 

Second, external radiation dose rates, or 

potential dose rates, especially during accident 

conditions, should be taken into account. 

When feasible, the TEDE of the entering 

personnel should be kept within the regulatory 

limits. 

If high dose rates and/or relatively long 

exposure times are anticipated, licensees are 

reminded of the following portions of the 

Code of Federal Regulations that address 

radiation doses in emergency situations: 

"* In 10 CFR 20.1001, Purpose, 

subparagraph (b) states (in part) that "nothing in this part shall be construed as 

limiting actions that may be necessary to 

protect health and safety." 

"* Licensed facilities where an emergency 

plan is required should review 10 CFR 

50.47, Emergency plans, subparagraph 

(b). This states (in part) "The onsite and," 

with certain exceptions "offsite emergency 

response plans for nuclear power reactors 

must meet the following standards: 

(11) Means for controlling radiological 

exposures, in an emergency, are 

established for emergency workers. The 

means for controlling radiological 

exposures shall include exposure 

guidelines consistent with EPA

Emergency Worker and Lifesaving 

Activity Protective Action Guides."' 

In paragraph 10 CFR 50.54 Conditions of 

licenses, subparagraph (x) states "A 

licensee may take reasonable action that 

departs from a license condition or a 

technical specification (contained in a 

license issued under this part) in an 

emergency when this action is 

immediately needed to protect the public 

health and safety and no action consistent 

with license conditions and technical 

specifications that can provide adequate or 

equivalent protection is immediately 

apparent." Subparagraph (y) continues 

with "Licensee action permitted by 

paragraph (x) of this section shall be 

approved, as a minimum, by a licensed 

senior operator, or, at a nuclear power 

reactor facility for which the certifications 

required under §50.82(a)(1) have been 

submitted, by either a licensed senior 

operator or a certified fuel handler, prior 

to taking the action." 

3.8.3 During the Initial Phase of an 

Operation 

When the potential for significant increase in 

airborne contamination is high during the first 

part of a work activity, even though airborne 

radioactivity measured prior to the start of 

work is low, respirators may be used until the 

potential source of airborne radioactivity has 

been contained or removed. 

3.8.4 While Process or Engineering 

Controls are Being Implemented 

Respirators may be used while such controls 

are being designed, ordered, fabricated or 

installed. 

' "Manual of Protective Action Guides and 

Protective Actions for Nuclear Incidents." US 

EPA, 400-R-92-001, May 1992.

NUREG/CR-0041, Revision 1 16
3.8.5 Where a Professional Judgment 

Mandates Such Use 

Professional judgment of licensee staff should 

always be the determining factor in 

circumstances that are not easy to analyze 

quantitatively with regard to respirator use. 

3.9 Inappropriate Uses of Respirators 

Using respirators for the following reasons is 

normally considered inappropriate use of these 

devices. 

3.9.1 Unjustifiable Work in Atmospheres 

IDLH 

Workers should not routinely be permitted to 

enter IDLH environments. Such entries should 

be specifically justified. Licensees should be 

reluctant to permit entries into IDLH 

environments unless all other reasonable 

alternatives have been considered. A 

procedure should be in place (e.g., confined

space entry) to guide the work. One such 

incident is described in IE Information 

Notice 81-26.2 

3.9.2 Compensation for Poor Work 

Practices 

The assignment of respirators to prevent 

workers from rubbing or touching their faces 

with contaminated gloves, or otherwise 

compensating for inadequate training or poor 

work practices is not proper. 

3.9.3 Eye Protection Only 

Assigning respirators primarily for the purpose 

of protecting the eyes from direct injury, or 

2 IE Information Notice 81-26: "Compilation of 

Health Physics Related Information Items, Part 4: 

Personnel Entry into Inerted Containment."

primarily for the purpose of providing beta 

particle shielding to limit radiation dose to the 

lens of the wearer's eyes should not be 

permitted. Eye protection can be provided 

more appropriately with safety glasses or face 

shields that impose fewer constraints and less 

stress on the wearer. 

3.9.4 Surface Contamination Levels 

Assignment of respirators due only to the 

presence of loose surface contamination in 

excess of certain concentrations without 

additional justification should be avoided. 

Automatically requiring the use of respirators 

because loose surface contamination in the 

work place is greater than some arbitrary 

concentration (e.g., 100,000 dpm/100 cm2), 

without additional justification, may not be 

considered ALARA. If an evaluation shows 

that the contamination is in loose, powdery 

form and likely to become airborne under the 

conditions of the work to be performed, 

respirator use might be considered ALARA 

depending on anticipated concentrations and 

exposure times. If the contamination is wet or 

oily and not likely to become airborne, then 

respirators might not be needed. In the 

respirator-use evaluation, consideration should 

also be given to other factors that would affect 

the potential for the contamination to become 

airborne. Some examples of such factors 

would be whether the contamination is dry and 

powdery; whether it is in the immediate work 

area or not; whether the exposed individuals 

will be inspecting or making measurements, or 

performing more aggressive work. In short, 

the ability or likelihood of the radioactive 

material going airborne should be factored 

into the decision to use or not use respirators. 

3.10 Airborne Particle Production 

Mechanical processes such as grinding, 

welding, flame cutting, brazing, sawing, 

flapper-wheeling, and other similar types of 

activities performed on contaminated or

17 NUREG/CR-0041, Revision I
irradiated components will produce airborne 

contamination in the form of particles. The sizes 

of these particles range from very large to very 

small. Large particles, well outside the so-called 

respirable size range, are of such (relatively) 

large mass that they will quickly settle out of the 

air and onto surfaces, and will not be airborne 

for very long. However, a sufficient fraction of 

the particles thus produced are small enough to 

remain airborne for long periods and to be 

inhaled by workers. 

For high-temperature operations such as 

welding, flame cutting, and brazing on 

radioactive or contaminated metal, the 

temperatures are much higher than in the 

friction-related processes described above. In 

these higher temperature processes, particles 

of metal and any contaminants that may be 

present on the metal will be vaporized. As 

these vapors cool and condense, very small 

particles called "fumes" are formed. Airborne 

vapors and fumes are very small and may 

remain airborne for a significant period of 

time. Small particles such as these in the range 

of 0.1 ptm MMAD are well within the so

called respirable range

and therefore, easily able to be drawn into the 

alveolar-interstitial (AI) region of a worker's 

respiratory system. Insoluble particles 

deposited in this region of the lung will remain 

in deep lung for relatively long periods of 

time. This is because the deep lung, the 

alveolar sacs, and the alveolar airways have no 

rapid or effective clearance mechanism as do 

the upper portions of the human respiratory 

system. Therefore, all personnel performing 

welding, flame cutting, brazing, or other high 

temperature work on any metals, radioactive 

or not, should be provided with some type of 

respiratory protection-engineered controls or 

respirators-for protection from the fumes. 

If the metal is also radioactive, the CDE and 

CEDE may need to be estimated and added to 

the individual's dose record. 

Refer to Appendix A of this Manual for a 

discussion of the human respiratory system and 

other information about particle collection 

mechanisms.

NUREG/CR-0041, Revision 1 18
References and Resources

1. "Manual of Protective Action Guides and Protective Actions for Nuclear Incidents." US EPA, 

400-R-92-001, May 1992. 

2. 2. IE Information Notice No. 81-26: "Compilation of Health Physics Related Information Items, 

Part 4: Personnel Entry into Inerted Containment." U.S. Nuclear Regulatory Commission, August 

28, 1981. 

3. Nelson, T.J. "The Assigned Protection Factor According to ANSI." AIHA Journal, 57: 735-740 

(1996). 

Associations and Organizations 

The American Society of Safety Engineers (ASSE) 

1800 E. Oakton St. 

Des Plaines, IL 60018 

(847) 699-2929: Fax: (847) 768-3434 

<www.asse.org> 

American Industrial Hygiene Association (AIHA) 

2700 Prosperity Ave., Suite 250 

Fairfax, VA 22031 

(703) 849-8888; Fax (703) 207-3561 

<www.aiha.org> 

National Fire Protection Association (NFPA) 

I Batterymarch Park 

Quincy, MA 02269-9101 

(617) 770-3000; Fax: (617) 770-0700 

<www.n fpa.org> 

International Society for Respiratory Protection (ISRP) 

Hazards Control Department 

Lawrence Livermore National Laboratory 

P.O. Box L-379 

Livermore, CA 94551 

<www.isrp.com> 

American Conference of Governmental Industrial Hygienists, Inc. 

1330 Kemper Meadow Dr., Suite 600 

Cincinnati, OH 45240 

(513) 742-2020 ; Fax: (513) 742-3355 

<www.acgih.org> (Web site contains links to many safety-related organizations.)

19 NUREG/CR-0041, Revision 1
National Safety Council 

1121 Spring Lake Drive 

Itasca, IL 60143-3201 

(630) 285-1121; Fax: (630) 285-1315 

<www.nsc.org> 

Health Physics Society (HPS) 

1313 Dolley Madison Boulevard, Suite 402 

McLean, Virginia 22101 

(703) 790-1745; Fax: (703) 790-2672 

<www.hps.org> 

Web Sites 

1. U.S. Nuclear Regulatory Commission, 

<www.nrc.gov> 

2. U.S. Environmental Protection Agency, 

<www.epa.gov> 

3. National Institute for Occupational Safety and Health (NIOSH), 

<www.cdc.gov/niosh/respinfo.htm 1> 

4. Occupational Safety and Health Administration (OSHA), 

<www.osha-slc.gov/html/subject-index.html>

NUREG/CR-0041, Revision I 20
4 EQUIPMENT

4.1 Introduction 

Since NUREG-0041 was published in 1976, 

significant advances in respiratory protection 

technology have taken place. In the sections 

below, operational descriptions of commonly 

used types of respiratory protection devices 

are provided, and the major advantages and 

limitations of each are listed. Devices that 

incorporate a combination of these devices 

into a single piece of equipment are also 

described. There is no single type of respirator 

that is best for use in all situations. The 

Respirator Program Administrator (RPA) 

should understand the advantages and 

limitations of each type of respirator in order 

to purchase appropriate devices, and to assign 

the proper devices in various field 

applications. 

The National Institute for Occupational Safety 

and Health (NIOSH) tests and certifies 

respiratory protection devices that meet 

specified design and operational criteria. A list 

of the manufacturers and model numbers of 

such devices are available from NIOSH.1 With 

the exception of the exemption for supplied

air suits, the NRC requires that only NIOSH

approved equipment be used in a radiological 

respiratory protection program, unless an 

exemption has been granted as described in 10 

CFR 20.1703(b). In addition, the licensee 

should use, maintain, and store these devices 

in such a manner that the approval is not 

voided.2 This means that each device should 

be used in accordance with the manufacturer's 

1 Available from Publications Dissemination, DSST, 

National Institute for Occupational Safety and Health, 

U.S. Department of Health and Human Services, 4676 

Columbia Parkway, Cincinnati, OH 45226. 

<http://www.cdc.gov/nioshlhomepage.html>. (Select 

"Databases" then "Certified Equipment List.") 

2 Steinmeyer, K. Paul. "NIOSH Approval Requirements 

for Respiratory Protection Equipment," Radiation 

Protection Management. Vol. 14, No. 5 (September

October 1997), pp. 48-52.

instructions and that they be repaired when 

necessary and maintained in "like-new" 

condition with allowance made for superficial 

signs of wear. 

The licensee should also provide adequate 

equipment or material as necessary to 

supplement respiratory protective equipment 

for the purpose of reducing the likelihood that 

respirator use might contribute to workplace 

accidents or injury. Examples of this type of 

equipment would be spectacle adapters, 

welding adapters, voice amplification 

equipment, material or equipment to prevent 

or reduce fogging of respirator lenses, and 

body-cooling equipment in high 

temperature/high humidity environments. 

Effective respirator use presumes a thorough 

knowledge of the capabilities and limitations 

of the device being used. This applies not only 

to the RPA and respirator users, but also to 

their supervisors, work planners, emergency 

planners, and trainers. 

4.2 The Respiratory Inlet Covering 

The respiratory inlet covering is the 

component of a respiratory protection device 

that isolates the breathing zone of the 

respirator wearer and protects it from the 

contaminants in the ambient air. Five general 

types of inlet coverings are commonly used in 

the nuclear industry. These are: 

"* Tight-fitting facepieces; 

"* Loose-fitting facepieces; 

"* Hoods; 

"* Helmets; and 

"* Suits.

21 NUREG/CR-0041, Revision I
Figure 4-1. Half-facepiece with replaceable 

cheek-mounted filter cartridges, and a full

facepiece with chin-mounted filter canister.

Figure 4-2. Loose-fitting facepiece with a 

powered air-purifying device.

4.2.1 Tight-Fitting Facepieces

Tight-fitting facepieces are those that depend 

on a seal between the facepiece and the face of 

the wearer to protect the respiratory tract. This 

class includes single-use disposable respirators 

(also referred to as dust masks), half-facepiece 

respirators and full-facepiece respirators. 

Contaminants are excluded from the wearer's 

respiratory tract by the face-to-facepiece seal 

in combination with either filtered ambient air, 

or air supplied from another source such as a 

pressurized air cylinder or a breathing air 

compressor. Drawings of two of these devices 

are shown in Figure 4-1. 

4.2.2 Loose-Fitting Facepieces 

Loose-fitting facepieces form only a partial 

seal with the face and do not completely cover 

the head or shoulders of the wearer. These 

devices often include a hard hat or a bump cap 

in their design. Respiratory protection systems 

that utilize a loose-fitting facepiece always 

operate in the positive-pressure mode. The 

wearer breathes either filtered ambient air that 

is blown into the facepiece (i.e., a powered air

purifying respirator), or compressed air 

supplied from another source (e.g., a constant

flow supplied-air respirator). A drawing of one 

of these devices is shown in Figure 4-2. 

4.2.3 Hoods 

Hoods completely cover the head and neck of 

the wearer. These are seen in two 

configurations. The first, usually used with a 

supplied-air device, is designed with a double 

shroud or bib on the front and on the back. 

The inner shroud (both front and back) is to be 

tucked into the protective clothing. The outer 

shrouds are designed to be secured to the 

outside of the protective clothing by means of 

a belt, which also acts as an attachment point 

for an air pressure reducer and the air supply 

hose. The inner shroud directs the air exhaust

NUREG/CR-0041, Revision I 22
from the hood down over the wearer's torso 

and provides effective body cooling. 

The second type incorporates a knit or elastic 

collar or neck dam that stays in close contact 

with the wearer's neck. Short front and back 

shrouds are usually also present. See 

Figure 4-3. 

Hoods always operate in a positive-pressure 

mode. The wearer breathes either filtered 

ambient air that is blown into the facepiece 

(i.e., a powered air-purifying respirator), or 

compressed air supplied from another source 

(e.g., a continuous-flow supplied-air 

respirator). A drawing of one of these devices 

is shown in Figure 4-4. 

4.2.4 Helmets 

Helmets are hoods that offer head protection Figure 4-3. Supplied air hood, short shroud 

for the wearer. They may be designed with 

long shrouds or with a knit or elastic 

neckband. Like hoods, these always operate in 

a positive-pressure mode and include a hard 

hat or a bump cap in their design. The wearer \jK',,, K 

breathes either filtered ambient air that is 

blown into the helmet (i.e., a powered air

purifying respirator), or compressed air ,\ (•,. 

supplied from another source (e.g., a ) '

continuous-flow supplied-air respirator). A /'\i 

drawing of one of these devices is shown in 

Figure 4-5. / /\?//// 

4.2.5 Suits / -] 

Suits are one- or two-piece whole body covers 

that are usually made of waterproof material. 

The respiratory inlet covering of a suit is Figure 4-4. Supplied-air hood, long shroud. 

similar to a hood. A supplied-air suit is shown 

in Figure 4-6.

NUREG/CR-0041, Revision I 23
Figure 4-6. One-piece supplied-air suit. 

4.3 Classification of Respirators 

Respirators can be classified in a variety of 

ways. Some of these are by: 

"* Respiratory inlet covering, 

"* Source of breathing air, and 

"* Mode of operation. 

Table 4-1 shows how respirators may be 

classified according to the respiratory inlet 

coverings described above.

A second way in which respirators may be 

classified is by the source of the breathing air 

provided to the wearer. Table 4-2 below shows 

respirators classified according to their source of 

breathing air. 

Respirators may also be classified by their mode 

of operation. Table 4-3 below shows how 

respirators may be classified in this way. 

Complete descriptions of these various modes 

of operation are provided below. 

It is common practice to combine these various 

classifications to accurately describe a specific 

respiratory protection device. Some examples 

would be: 

"* Half-facepiece, negative pressure, air

purifying respirator; 

"* Full-facepiece, positive-pressure, air

purifying respirator; and 

"* Full-facepiece, pressure-demand, SCBA. 

4.4 Negative-Pressure Air-Purifying 

Respirators (APRs) 

4.4.1 Negative-Pressure Devices--General 

Negative-pressure air-purifying respirators, 

both half- and full-facepiece, are the most 

commonly used of all respiratory protection 

devices. They remove contaminants from 

ambient air by filtration, absorption or 

adsorption of the contaminants, depending on 

the contaminant and on the cartridges or 

canister selected. This type of device is 

usually the least costly to purchase but, except 

for the disposable types, requires periodic 

maintenance and filter replacement. Of all the 

types of respiratory protection devices 

available, they weigh the least and allow 

maximum mobility to the wearer. They do not, 

however, supply oxygen and depend on the 

quality of filtered ambient air to sustain the 

wearer. Therefore, they cannot be used for fire 

fighting or in other oxygen-deficient 

environments.

NUREG/CR-0041, Revision I 24
Table 4-1. Classification of respirators by type of respiratory inlet covering.

Tight-Fitting Loose-Fitting 

Facepiece Facepiece Hood/Helmet Suit 

Half-Facepiece Full-Facepiece Air-purifying PP Air-purifying PP Supplied air CF 

Air-purifying NP Air-purifying NP Supplied air CF Supplied air CF 

Air-purifying PP Air-purifying PP Escape only 

SCBA 

Supplied air Supplied air 

D, CF, PD D, CF, PD 

SCBA D, PD 

SCBA RD, RP 

PP = positive pressure (air-purifying) CF = continuous flow (supplied-air) 

D = demand PD = pressure demand 

NP = negative pressure RD = recirculating demand (closed-circuit SCBA) 

RP = recirculating positive pressure 

(closed-circuit SCBA). 

Table 4-2. Classification of respirators by source of breathing air. 

Air Purifying (AP) Supplied-Air Respirator (SAR) SCBA 

Disposable dust masks, NP Elastomeric half-facepiece, Full facepiece, D, PD 

D, CF, PD 

Half facepiece, NP Full facepiece, D, CF, PD Full facepiece, RD, RP 

Full Facepiece, NP Hood, CF 

Hood/helmet w/filter and blower, Helmet, CF 

PP 

Loose-fitting facepiece, PP Suit, CF

PP = positive pressure (air-purifying) 

D = demand 

NP = negative pressure 

RP = recirculating positive pressure 

(closed-circuit SCBA).

CF = continuous flow (SAR) 

PD = pressure demand (SAR and open-circuit SCBA) 

RD = recirculating demand (closed-circuit SCBA)

NUREG/CR-0041, Revision 1 25
Table 4-3. Classification of respirators by mode of operation. 

Negative Positive Continuous Pressure- Pressure- Recirculating Pressure Pressure Flow Demand Demand Positive 

(AP and SAR (Powered Air- (SAR) (SAR) (Open circuit Pressure 

Demand) Purifying) SCBA) (Closed circuit 

SCBA) 

Disposable Elastomeric Elastomeric Elastomeric Full facepiece Full facepiece dust mask half-facepiece half facepiece half facepiece 

w/filter and 

blower 

Reuseable half Full facepiece Full facepiece Full facepiece 

facepiece w/filter and 

blower 

Elastomeric Hood/helmet Hood/Helmet 

half facepiece w/filter and 

blower 

Full Facepiece Loose-fitting Suit 

facepiece 

w/filter and 

blower 

AD= 4, .'r -1~ t- .-au-put iy, 6 otR- suppnleu-air respirator

Figure 4-7. Negative-pressure respirator operation.

Negative pressure respirators must always 

utilize a tight-fitting facepiece. In a negative

pressure device, the air pressure inside the 

facepiece is negative with respect to the air 

pressure outside the device during inhalation. 

This differential pressure causes the exhalation 

valve to close, and ambient air to pass through 

the facepiece filter and inhalation valve to 

equalize the pressure inside. This also means 

that if there is a leak in the face-to-facepiece 

seal area, or if there is a hole in the facepiece, 

some contaminated air will be drawn into the

inlet covering through this unprotected 

pathway during the negative pressure portion 

of the breathing cycle. Upon exhalation, air 

pressure inside the facepiece is greater than 

ambient, so the inhalation valve is forced 

closed, the exhalation valve is opened by the 

pressure in the facepiece, and the exhaled air 

is discharged. The inhalation valve prevents 

back-flow of exhaled air through the filter. 

Some respirators are designed with no 

exhalation valves, and some are not equipped

NUREG/CR-0041, Revision 1 26
with inhalation valves. Negative-pressure 

facepiece operation is illustrated in Figure 4-7. 

Obviously, the fit of the facepiece on the 

wearer's face is of critical importance to the 

proper operation of respiratory protection 

devices that operate in this mode. Of all the 

modes of respirator operation, the negative

pressure mode is the least protective of the 

wearer. If properly fitted and used, however, 

negative-pressure respirators provide adequate 

protection in relatively low concentrations of 

airborne contaminants. 

4.4.2 Quarter-Facepiece Respirators, 

Negative Pressure Mode 

Quarter-facepiece respirators seal over the 

bridge of the nose, around the cheeks, and 

between the point of the chin and the lower 

lip. It has been observed that the fit becomes 

unstable when the wearer moves around in the 

work place, especially when the wearer talks. 

These devices have always been, and continue 

to be prohibited in an NRC-regulated 

respirator program (10 CFR 20 Appendix A, 

footnote e). Good alternatives such as half

facepiece respirators are readily available. 

4.4.3 Half-Facepiece Respirators--General 

Half-facepiece respirators seal over the bridge 

of the nose, around the cheeks, and under the 

chin. Traditionally, half-facepiece respirators 

are made of rubber or an elastomeric material 

(e.g., silicone rubber), have at least two 

adjustable elastic head straps (4-point 

suspension), and usually use two replaceable 

filter cartridges mounted opposite the cheeks of 

the wearer. In recent years, two somewhat 

different designs have come onto the market. 

Some of these have a standard rubber or 

elastomeric facepiece with filters attached, but 

the filters are not replaceable. These devices are 

considered to be half-facepiece respirators. In 

the others, called "filtering facepiece"

respirators, the filter medium is an integral part 

of the facepiece structure and is not replaceable. 

NRC divides half-facepiece respirators into 

two categories: dust masks and half

facepieces. General industry (e.g., OSHA, 

ANSI) does not make this distinction. More 

information about the differences between 

dust masks and half-facepieces may be found 

in Regulatory Guide 8.15, Revision 1, October 

1999. An experienced respirator program 

administrator should be able to distinguish 

between these single-use, filtering facepiece 

dust masks and those that qualify as half

facepiece respirators in an NRC-regulated 

program. 

4.4.4 Dust Masks, Negative Pressure Mode 

All dust masks are "filtering facepieces," 

meaning that the filter medium is an integral 

part of the facepiece and is not replaceable. Dust 

masks are generally considered to be single-use 

disposable respirators. The filter medium is 

relatively thin, they usually don't contain an 

exhalation valve, and the head straps are usually 

not adjustable. Any filtering facepiece that does 

not meet the definition of a half-facepiece (see 

4.4.5 below) is a dust mask. 

Appendix A to 10 CFR 20 does not assign an 

APF to "filtering facepieces" that are not 

equipped with elastomeric face seals and at 

least two adjustable straps, unless the licensee 

can demonstrate a fit factor of at least 100 by 

use of a quantitative or validated or evaluated 

qualitative fit test. If the device can be fit

tested to demonstrate a fit factor of at least 

100, then an APF of 10 may be used. 

Although stated differently, this is essentially 

the condition that ANSI would require of 

disposables. The NRC believes that some 

devices such as dust masks may not retain 

good fit under conditions of use in the 

workplace. 

The NRC and OSHA also permit the use of 

dust masks and other disposables, if requested

27 NUREG/CR-0041, Revision 1
by a worker, without the requirement to 

perform medical screening or fit tests. Fit

testing is only required if APF credit is taken 

for use of the device in estimating intake or 

dose, suggesting that the intent is to limit 

intake of radioactive material. 

Anticipated applications of dust masks would 

be situations where a respirator is not 

necessary, but is requested by a worker (i.e., 

voluntary respirator use). This type of 

respirator can limit intakes of nuisance dusts 

when use of a more protective device cannot 

be justified in an ALARA analysis. 

4.4.5 Haif-Facepiece Respirators, Negative 

Pressure Mode 

Half-facepiece respirators, as recognized by 

the NRC, may be the traditional rubber 

facepiece with replaceable filter cartridges, a 

rubber facepiece with filter cartridges that 

can't be replaced, or they may be filtering 

facepieces. In order for a filtering facepiece to 

be considered a half-facepiece respirator, it 

must have both of two design characteristics. 

Seal-enhancing rubber or elastomeric material 

must be applied to the entire face-to-facepiece 

seal area (by the manufacturer), and an 

adjustable four-point (minimum) suspension 

strap system must be part of the design. Most 

of the devices that qualify as half-facepiece 

respirators also have exhalation valves, but an 

exhalation valve, while desirable, is not an 

essential design component. 

4.4.6 Full-Facepiece Respirators, Negative 

Pressure Mode 

Full-facepiece respirators seal across the 

forehead between the hairline and the eyebrows; 

down over the temples between the eyes and the 

ears; then down and around the jaw and chin. 

Full-facepiece respirators are made of rubber or 

an elastomeric material (e.g., silicone rubber), 

have a four- or five-point suspension system, 

and use either two cheek-mounted filter

Figure 4-8. Full-facepiece with replaceable, 

cheek-mounted filters.

Figure 4-9. Full-facepiece with 

replaceable, chin-mounted filter. 

cartridges, or one chin-mounted filter canister. 

Figures 4-8 and 4-9 show examples of these 

respirators. The filters are traditionally 

replaceable, but a somewhat different design is 

manufactured with non-replaceable filters 

installed.

NUREG/CR-0041, Revision I 28
4.4.7 Advantages and Limitations of 

Negative Pressure Air-Purifying 

Respirators 

Tables 4-4 through 4-6 summarize the major 

advantages and limitations of the various types 

of negative-pressure air-purifying respirators. 

Table 4-4. Advantages and limitations of dust 

masks (negative-pressure, air-purifying 

respirators). 

Dust Masks 

Advantages Limitations 

"* Relatively 0 Negative-pressure 

inexpensive device 

"* Little or no impact e No APF credit 

on worker vision unless fit testing 

or mobility and medical 

" Add little or no screening 

cardiopulmon- performed, low 

ary stress or heat APF (<10) 

stress 0 Should not be 

" Little impact on available to 

verbal untrained 

communication individuals 

" Create very little • Should ensure 

solid radioactive they are not 

waste, mistakenly 

" Voluntary use substituted for a 

requires no more protective 

medical screen- device 

ing or fit 0 Protection from 

testing.* particulates only 

"* Minimal wearer . May be difficult 

training required to perform user 

"* Will not affect seal check 

worker mobility

* If no APF is applied.

Table 4-5. Advantages and limitations of half

facepieces (negative-pressure, air-purifying 

respirators).

Table 4-6. Advantages and limitations of full

facepiece, negative-pressure, air-purifying 

respirators.

NUREG/CR-0041, Revision I

Half Facepiece (NP, APR) 

Advantages Limitations 

"* Relatively 0 May impact 

inexpensive verbal com

"* Little or no impact munication 

on worker vision 0 Low APF (<10) 

or mobility 0 Can add cardio

"* Small and easy to pulmonary 

maintain stress or heat 

"* Little interference stress 

with worker 0 Negative-pres

mobility sure device 

"* Many different 0 Breathing re

filters are available sistance in

"* Easy to use with creases with use, 

minimum training especially in 

"* Light weight, small dusty environ

size ments 

"* Easy to maintain * Fit test required

Full Facepieces (NP, APR)

Advantages Limitations 

"• Little impact on 0 Expense 

worker mobility 0 Vision restricted 

"• Good APF (_<I00) e Can add 

"* Relatively small cardiopulmonary 

and easy to stress or heat 

maintain stress 

"* Many different * Impact verbal 

filters are available communication 

"• Relatively easy to * Negative

use with proper pressure device 

training • Breathing 

resistance 

increases with 

use, especially in 

dusty 

environments 

* Fit test required 

a More extensive 

maintenance 

needed

29
Figure 4-10. Powered air-purifying respirator 

with full facepiece.

4.5 Powered Air-Purifying 

Respirators (PAPRs) 

4.5.1 General 

These devices may utilize either a tight-fitting 

facepiece, a loose-fitting facepiece, a hood, or 

a helmet as a respiratory inlet covering. 

Powered air-purifying respirators include one 

or more filters, a battery-operated blower, a 

rechargeable battery, and a flexible breathing 

tube that transfers air from the blower 

discharge to the respiratory inlet covering. 

Due to their weight, batteries are usually 

mounted on the wearer's waist. Filters and 

blower may be waist-mounted, or facepiece

mounted for devices that use a facepiece. 

When the blower motor is energized, ambient 

air is drawn through the filters and blown into 

the respiratory inlet covering continuously, 

maintaining the pressure in the respiratory 

inlet covering above atmospheric pressure. 

The excess air is discharged through one or 

more exhalation valves (full-facepiece 

between the face and the facepiece [loose

fitting facepiece]) or past the neck dam and/or 

front and rear shrouds (hood or helmet types). 

In case of leakage in the respiratory inlet 

covering, filtered air is much more likely to 

leak out rather than contaminated air leaking 

in. Figure 4-10 shows a powered air-purifying 

respirator with a full facepiece in use. 

Operation of a positive-pressure device is 

illustrated in Figure 4-11.

Figure 4-11. Positive-pressure (PAPR) respirator operation. Air supply is filtered ambient air.

NUREG/CR-0041, Revision I 30
This type of operation is referred to as the 

"positive pressure" or PP mode. This 

distinguishes it from the various modes of 

operation of supplied-air respirators described 

below (i.e., demand, constant-flow and 

pressure-demand). 

It is possible, but not likely, for a respirator 

user to over-breathe or out-breathe a positive 

pressure device. This means that a person 

breathing very heavily could, at the peak of a 

strong inhalation, cause the pressure inside the 

respirator inlet covering to become negative 

with respect to the contaminated ambient air. 

This would only be the case for a very short 

time, however, and it is unlikely that a person 

could maintain this breathing volume (high 

work rate) for more than a few breaths. The 

minimum flow rate to a facepiece-equipped 

PAPR is 115 1pm (4 cfm), and to a hood- or 

helmet-equipped device it is 170 lpm (6 cfm). 

Several manufacturers have designed their 

devices to exceed these minimum 

requirements so that at the end of a work shift 

when the battery is no longer fully charged, 

the blower still delivers greater than the 

minimum air flow. Over-breathing is less of a 

concern with a PAPR that utilizes a tight

fitting facepiece, since additional air drawn 

into the facepiece would come through the 

PAPR filters. This would not be the case with 

non face-sealing PAPRs. 

The initial cost of a PAPR is substantially 

more than a negative-pressure device. 

Continuing maintenance costs include 

recharging the battery between uses, and 

periodically discharging and recharging the 

batteries to ensure that the blower will deliver 

enough respirable air to the respiratory inlet 

covering. A battery has a limited useful life 

and cannot be recharged indefinitely and 

battery replacement can be expensive. Air 

blowers may need to be replaced if they fail. 

Some hood type devices require some pre-use 

assembly or replacement of the hood, 

breathing tube, and possibly other parts 

making them more maintenance intensive.

Other possible disadvantages, depending on 

the specific device, include weight, bulk, 

complex design, the need for ongoing 

maintenance, and at least daily replacement of 

air-purifying elements. Out-of-doors use 

presents special problems if hot or very cold 

air is supplied to the respiratory inlet covering. 

Filters may not be available for hazards other 

than airborne particulates. 

4.5.2 Advantages and Limitations of 

Positive Pressure Air-Purifying 

Respirators 

Tables 4-7 through 4-9 summarize the major 

advantages and limitations of facepiece-type, 

hood-type, and helmet-type positive-pressure 

air-purifying respirators. The advantages and 

limitations of loose-fitting facepieces are 

similar to those of hoods, except that the APF 

is 25. 

4.5.3 Respirator Filters 

NIOSH Regulations 

On July 10, 1995, the requirements for 

certification of respirators were moved from 

30 CFR II (Mine Safety and Health 

Administration) to 42 CFR 843 (Department of 

Health and Human Services). The role of 

NIOSH in the testing and certification of 

respirators is discussed below. The only 

substantive changes made so far during the 

shift in respirator approval regulations involve 

air-purifying respirators, and deal primarily 

with how filters for non-powered air purifying 

respirators are classified. Formerly, respirator 

filters had been categorized as "dust/mist," 

"dust/mist/fume," etc. The 42 CFR 84 system 

establishes nine classes of air-purifying 

particulate filters, categorized as to their 

efficiency and resistance to oil aerosols. 

3 The full text of 42 CFR 84 "Respiratory Protective 

Devices" can be found at 

<http:i/'.www.cdc.gov/niosh/respinfo.html>.

31 NUREG/CR-0041, Revision I
Table 4-7. Advantages and limitations of facepiece-type, positive-pressure, air-purifying respirators.

Table 4-8. Advantages and limitations of hood-type, positive-pressure, air-purifying respirators. 

Hood-Type Positive Pressure Air-Purifying Respirator 

Advantages Limitations 

"* No fit test required * Expense 

"* May be used by workers with facial hair or * Vision restricted 

deformities a Impact verbal communication 

" Many hoods provide better vision than facepiece- e Air blowing into wearer's breathing zone 

or helmet types may be uncomfortable, especially in hot or 

"* Little impact on worker mobility cold environments 

"* Reduced breathing resistance a Much more extensive maintenance needed 

"* Usually very comfortable for wearer * Use in dusty environments may reduce 

"* Positive-pressure device airflow rate due to filter loading 

"* High APF (=1000) 9 Not for use in IDLH 

"* May reduce cardiopulmonary stress or heat stress 

"* Relatively easy to use with proper training 

"* Long use duration 

"* Adaptable to voice amplifiers and 

communications systems _

Table 4-9. Advantages and limitations of helmet-type, positive-pressure, air-purifying respirators.

Advantages

* No fit test required 

* May be used by workers with facial hair or 

deformities 

* Little impact on worker mobility 

* Reduced breathing resistance 

* Usually very comfortable for wearer 

* Positive-pressure device 

* High APF (=1000) 

* May reduce cardiopulmonary stress or heat stress 

* Relatively easy to use with proper training 

* Long use duration 

* Adaptable to voice amplifiers and 

communications systems

Limitations

"* Expense 

"* Vision restricted 

"* Impact verbal communication 

"* Air blowing into wearer's breathing zone 

may be uncomfortable, especially in hot or 

cold environments 

"* Much more extensive maintenance needed 

"* Use in dusty environments may reduce 

airflow rate due to filter loading 

"* Not for use in IDLH

NUREG/CR-0041, Revision I

Facepiece-Type Positive Pressure Air-Purifying Respirator I. -. -

" Little impact on worker mobility 0 Expense 

"* Reduced breathing resistance 0 Vision restricted 

"* Usually very comfortable for wearer * Impact verbal communication 

"* Positive-pressure device e Air blowing in wearer's face may be 

"* High APF (<OO0) uncomfortable, especially in hot or cold 

"* May reduce cardiopulmonary stress or heat stress environment 

"* Relatively easy to use with proper training 9 Fit test required 

"* Long use duration 0 Much more extensive maintenance needed 

* Use in dusty environments may reduce 

airflow rate due to filter loading 

e Not for use in IDLH

Helmet-Type Positive Pressure Air-Purifvine ResDirator

32

i

I

Auvantages Limitations
Table 4-10. New filter categories, 42 CFR 84. 

Not for 

Use in 

Minimum Oil Oil- Oil

Efficiency Aerosol Resistanttl Proofý 

Environ

ments" 

95% N95 R95 P95 

99% N99 R99 P99 

99.97% NI00 R100 P100 

* Tested with NaC1 aerosol 

t Use time restrictions may apply 

STested with DOP, MMAD=0.3pm 

Table 4-10 summarizes these new filter 

categories. NIOSH intends to revise the other 

sections of 42 CFR 84 one module at a time. 

Manufacturers could no longer manufacture or 

ship 30 CFR 11-approved respirators after 

July 10, 1998. By this date, respirator 

manufacturers had received a new approval 

number for each of their devices. If these re

approved facepieces are identical to those 

approved under 30 CFR 11, then the new 

category filters may be used with the old 

facepieces. If the manufacturer redesigned the 

facepiece, however, before submitting it to 

NIOSH for approval, then the old facepieces 

may not be used with the new 42 CFR 84

approved filters. These old facepieces will 

continue to be approved devices only for as 

long as 30 CFR 11-approved filters are 

available for them. RPAs should verify that 

their equipment has been re-approved under 

42 CFR 84. 

HEPA Filters 

Previous versions of NRC regulations required 

the use of so-called HEPA (high-efficiency 

particulate air) filters on air-purifying 

respirators used for protection against airborne 

particulate radionuclides. The term "HEPA 

filter" was never defined or used by NIOSH in 

30 CFR 11, and this continues to be true in 42

CFR 84. The former, 30 CFR 11, required 

dust-fume-mist filters to pass a DOP (dioctyl 

phthalate) test, and the DOP had to be 

thermally generated. Therefore, they met all 

the requirements for a high efficiency (HEPA) 

filter, but the term was never used. The term 

HEPA probably came out of the air cleaning 

industry. NIOSH now (42 CFR 84) only talks 

about percent filter efficiency, and specifies 

the challenge aerosol to be used and the 

acceptable range of particle sizes. 

High efficiency particulate air (HEPA) filter is 

defined as "a filter that is at least 99.97% 

efficient in removing monodisperse particles 

of 0.3 micrometers in diameter." The 

equivalent NIOSH 42 CFR 84 particulate 

filters are the N100, R100, and P100 filters. 

Although NIOSH has revised the particulate 

filter descriptions under the new 42 CFR Part 

84 respirator certification regulation, and does 

not use the term HEPA, this definition is 

included here because "HEPA filter" is used 

widely in the literature and in some of 

OSHA's substance-specific standards. 

The use of "thermally generated dioctyl 

phthalate (DOP)" also presents some 

problems, including operator exposure to the 

DOP vapors (a possible carcinogen) and rather 

complex test equipment. The thermal 

generation process requires the DOP oil to be 

heated and vaporized then cooled, forming 

condensation nuclei of approximately 0.3 pam 

mass median aerodynamic diameter (MMAD). 

Under 42 CFR 84, N-type filters will be tested 

with sodium chloride aerosol (count median 

diameter = 0.075±0.020 [tm), and R- and P

types will be tested with DOP particles 

produced in a non-thermal process (count 

median diameter = 0.185±0.020 rim). These 

count median diameters translate to a mass 

median aerodynamic diameter (MMAD) of 

0.3 Itm. Manufacturers may still test filters 

with hot DOP, however.

NUREG/CR-0041, Revision 1 33
Limitations of Respirator Filters 

NIOSH approves respirator filter cartridges 

and canisters for some maximum 

concentrations of contaminant (e.g., 

20 mg/mr3). If actual or anticipated 

concentrations exceed that value, a more 

protective device, such as a supplied-air 

respirator should be selected. 

4.6 Supplied-Air Respirators (SARs) 

4.6.1 General 

Supplied-air respirators (SARs) and self

contained breathing apparatus (SCBA) belong 

to a class of respirators called "atmosphere

supplying respirators." They may operate in 

any one of three possible modes: demand 

(negative-pressure), constant flow, or pressure

demand. SCBA are discussed later in this 

chapter. All airline-supplied respirators, 

regardless of mode of operation, require a 

protected breathing air source and an air 

distribution system, which is expensive. The 

user is then tethered to this air supply by a 

hose. One big advantage of airline respirators 

is that they may be used for long continuous 

periods. 

The limitations of supplied-air respirators are 

the potential consequences of a loss of the 

source of respirable air supplied to the 

respiratory inlet covering, and tangling 

problems associated with the attached air hose. 

Such loss may be caused by cutting, burning, 

kinking, or crushing the supply air hose, by air 

compressor failure, or by depletion of the 

respirable air in a storage tank. Possible loss of 

respirable air supports the NIOSH 

recommendation against airline respirator use 

in IDLH atmospheres. SARs are never used 

for fire fighting because the air hose is 

vulnerable to damage. (Combination devices, 

such as an airline respirator with an auxiliary 

self-contained air supply, could be used in 

such atmospheres because the auxiliary self

contained air supply can be used for escape.

These devices are covered later in this 

chapter.) The trailing air supply hose of the 

airline respirator limits the wearer's mobility. 

The maximum hose length allowed by NIOSH 

is 300 feet. Some devices are certified for 

shorter hose lengths. This may make the 

airline respirator unsuitable for those who 

move frequently between widely separated 

work stations. 

4.6.2 Demand Mode Supplied-Air 

Respirators (Negative Pressure) 

Respirators that operate in the demand mode 

are negative-pressure devices and require the 

use of a face-sealing respiratory inlet covering. 

A regulator is mounted either on the wearer's 

waist and connected to the facepiece by a 

breathing tube, or it is mounted directly on the 

facepiece. As the wearer inhales, the pressure 

inside the facepiece becomes negative with 

respect to atmospheric pressure. This pressure 

differential causes an exhalation valve 

installed in the facepiece to close, preventing 

ambient air from entering the facepiece. It also 

moves a rubber diaphragm in the regulator, 

which bears on a lever, which opens an 

admission valve. As the admission valve 

opens, breathing air from a remote source 

flows through the valve and into the 

respiratory inlet covering. When pressure 

inside the facepiece equals atmospheric 

pressure at the end of inhalation, the 

diaphragm moves away from the admission 

valve lever and the air stops flowing to the 

facepiece. When the wearer begins to exhale, 

air pressure inside the facepiece exceeds 

atmospheric pressure, and the exhalation valve 

in the facepiece opens, allowing exhaled air to 

exit the facepiece without disturbing the face 

seal.

NUREG/CR-0041, Revision I 34
4.6.3 Advantages and Limitations of 

Negative Pressure, Demand, 

Supplied-Air Respirators 

Table 4-11 summarizes the major advantages 

and limitations of supplied-air respirators 

operating in the demand mode. 

Table 4-11. Advantages and limitations of 

facepiece-type, demand supplied-air respirators.

4.6.4 Constant Flow Mode (CF) 

The term "constant flow" or "continuous 

flow" is applied to supplied-air respirators that 

deliver breathing air to a respiratory inlet 

covering in a continuous stream. The inlet 

covering may be a face-sealing device, a hood 

or a helmet. The air is supplied from a secure 

air source such as a bank of cylinders or from 

a compressor through an air distribution 

header. As with positive-pressure devices, if 

the respiratory inlet covering is compromised, 

the supplied air is much more likely to leak 

out rather than contaminated air leaking in. 

Constant-flow respirators are almost always 

used in conjunction with a compressor

supplied air distribution system.

Advantages Limitations 

* None 0 More expensive than 

APR 

* Air supply system 

required 

* Vision restricted 

* Limited cooling in 

hot environments 

* Impact verbal 

communication 

* Negative-pressure 

device 

* Low APF 

* Mobility restricted 

due to air umbilical 

* Fit test required 

* More extensive 

maintenance needed 

than for APR 

* Not for use in IDLH 

* Could be mistaken 

for a more protective 

device

Figure 4-13. Constant flow respirator operation.

NUREG/CR-0041, Revision I

Half- and Full-Facepiece Demand Supplied

Air Respirators

Figure 4-12. Constant-flow supplied-air 

respirator with a full facepiece.

35
The large volume of air required to operate 

these devices usually exclude their use with air 

supplied by a bank of pressurized cylinders. 

Mobility is limited by the 300-foot maximum 

length of the attached air hose. Figure 4-12 

shows a constant-flow SAR in use. Operation 

of a constant-flow device is illustrated in 

Figure 4-13. 

It is possible, but not likely, for a respirator 

user to over-breathe or out-breathe a constant

flow SAR. This means that a person breathing 

very heavily could, at the peak of a strong 

inhalation, cause the pressure inside the 

respirator inlet covering to become negative 

with respect to the contaminated ambient air. 

This would only be the case for a very short 

time, however, and it is unlikely that a person 

could maintain this breathing volume (high 

work rate) for more than a few breaths. The 

minimum flow rate to a facepiece-equipped 

SAR is 115 1pm (4 cfm), and to a hood- or 

helmet-equipped device it is 170 Ipm (6 cfm). 

4.6.5 Advantages and Limitations of 

Supplied-Air-Respirators 

Tables 4-12 through 4-14 summarize the 

major advantages and limitations of facepiece

type, hood-type, and helmet-type supplied-air 

respirators. 

4.6.6 Pressure-Demand Mode 

Supplied-air respirators (airline) and SCBA 

can both operate in the pressure-demand 

mode. Pressure-demand operation always 

requires a tight-fitting facepiece. A pressure 

greater than atmospheric is maintained inside 

the facepiece throughout the breathing cycle. 

Because the exhalation valve is spring loaded 

in the closed position, air is prevented from 

being exhausted until facepiece pressure 

exceeds the spring tension. The regulator also 

has a spring that forces the regulator to deliver 

air to the facepiece until the pressure is just 

below the set point of the exhalation valve.

Therefore, if a person wearing a pressure

demand device holds his breath momentarily, 

no air will flow through the regulator and the 

facepiece will contain a slight pressure. As the 

wearer begins to inhale, the facepiece pressure 

begins to decrease but remains greater than 

ambient pressure. This decrease is sensed by 

the regulator, which begins to supply air to the 

facepiece, maintaining the positive pressure. 

As exhalation begins, the increasing pressure 

in the facepiece exceeds the set point of the 

exhalation valve, the valve opens, and air is 

exhausted from the system. Thus, through all 

phases of the breathing cycle, the pressure 

inside the facepiece is greater than 

atmospheric pressure. Any leakage past the 

Table 4-12. Advantages and limitations of 

facepiece-type, constant-flow supplied-air 

respirators.

NUREG/CR-0041, Revision 1

Half- and Full-Facepiece Constant Flow 

Supplied-Air Respirators 

Advantages Limitations 

SLess * More expensive than 

complicated APR 

operation and * Vision restricted 

maintenance 0 Limited cooling in 

than pressure- hot environments 

demand • Impact verbal 

devices, communication 

* High APF • Mobility restricted 

due to air umbilical 

* Loss of air supply 

requires removal of 

facepiece 

0 Fit test required 

0 More extensive 

maintenance needed 

* Limited body cooling 

in high-temperatures 

* May be 

uncomfortable for 

long durations 

* Not for use in IDLH

36
Table 4-13. Advantages and limitations of hood

type, constant-flow, supplied-air respirators.

face-seal area or through a defect in the 

facepiece would cause the pressure to decrease 

to below the regulator set point, and the 

regulator would supply additional air to the 

facepiece. In this situation, the respirator 

wearer would immediately know that there 

was an air leak in the system because the 

regulator would be supplying air continuously 

and not just during the inhalation phase of the 

respiration cycle. Figure 4-14 shows a 

positive-demand SAR in use, and Figure 4-15 

illustrates pressure-demand respirator 

operation.

Table 4-14. Advantages and limitations of 

helmet-type, constant-flow, supplied-air 

respirators.

It is possible for a respirator user to over

breathe or out-breathe a SAR operating in the 

pressure-demand mode. This means that a 

person breathing very heavily could, at the 

peak of a strong inhalation, cause the pressure 

inside the facepiece to become negative with 

respect to the contaminated ambient air. This 

would only be the case for a very short time, 

however, and it is unlikely that a person could 

maintain this breathing volume (high work 

rate) for more than a few breaths. 

Pressure-demand operation is considered to be 

the most protective mode of operation 

available at this time. Since wearers of

NUREG/CR-0041, Revision I

Hood-Type Constant Flow Supplied-Air 

Respirators

Advantages Limitations 

"* Many hoods 0 More expensive 

provide better than APR 

vision than 0 Impact verbal 

facepiece- or communication 

helmet types 0 Mobility restricted 

"* High APF due to air umbilical 

"* No fit test 0 Requires a 

required protected breathing 

"* Less expensive air source and an 

than pressure- air distribution 

demand devices system 

"* Less complicated * Air blowing into 

operation and wearer's breathing 

maintenance than zone may be 

pressure-demand uncomfortable, 

devices especially in hot or 

"* Hoods are often cold environments 

single-use items * Not for use in 

"* Provide excellent IDLH 

body cooling in 

high-temperature 

and/or high 

humidity areas 

"* Adaptable to 

voice amplifiers 

and 

communications 

systems

Helmet-Type Constant-Flow Supplied-Air 

Respirator

Advantages Limitations 

"* High APF 9 More expensive "* Less complicated than APR 

operation and * Vision restricted 

maintenance than 0 Impact verbal 

pressure-demand communication 

devices 0 Requires a 

"* Head protection protected "* May provide body- breathing air 

cooling in high- source and an 

temperature and/or air distribution 

high humidity system 

areas. * Mobility limited 

"* Very good by length of 

protection provided attached air 

"* Less complicated hose 

operation and 0 Consumes large 

maintenance than volume of air 

pressure-demand 0 Not for use in 

devices IDLH 

" Adaptable to voice 

amplifiers and 

communications 

systems

37
Figure 4-14. Pressure-demand supplied-air respirator with full facepiece.

Figure 4-15. Pressure-demand respirator operation.

Table 4-15. Advantages and limitations of full-facepiece, pressure-demand, supplied-air respirators. 

Full-Facepiece Pressure-Demand Supplied-Air Respirators 

Advantages Limitations 

"* No better protection available 9 Expense 

"* Less expensive than SCBA * Vision restricted 

"* Less complicated operation and maintenance than 0 Limited cooling in hot environments 

SCBA * Impact verbal communication 

* Mobility restricted due to air umbilical 

* Fit test required 

* More extensive maintenance needed 

0 Requires protected breathing air source 

and air distribution system 

0 Not for use in IDLH

NUREG/CR-0041, Revision I 38
pressure-demand devices have to exhale with 

some force to overcome the spring tension in 

the exhalation valve, this fact should be 

brought to their attention during training. The 

slight effort expended during exhalation is the 

indication that the system is operating 

properly. 

4.6.7 Advantages and Limitations of 

Pressure-Demand, Supplied-Air 

Respirators 

Table 4-15 summarizes the major advantages 

and limitations of full-facepiece supplied-air 

respirators operating in the pressure-demand 

mode. 

4.7 Self-Contained Breathing Apparatus 

(SCBA) 

4.7.1 Introduction 

While SCBAs are essentially just another type 

of supplied-air respirator, they are always 

considered to be in a special category of 

atmosphere-supplying devices since they are 

almost always the respirator of choice for 

entry into IDLH and other truly hazardous 

environments. The primary differences 

between them and other SARs are: 

"* The air supply source is totally under the 

control of the wearer; 

"* They are equipped with an emergency 

regulator bypass in case of regulator 

failure; and 

"* They are equipped with a low-pressure 

alarm. 

SCBAs are the most complex type of 

respiratory protection device available. They 

require a good deal of upkeep and testing in 

order to ensure that they will operate properly 

when they are needed. They also require that 

the user be highly trained to use the device 

properly.

The constant-flow mode of operation is not 

adaptable to SCBA operation, due to the large 

volume of air consumed by CF systems. The 

limited air supply in the user-carried cylinder 

would be expended quickly. The emergency 

escape feature on open-circuit SCBA, 

however, turns the device into a CF device by 

bypassing the regulator and supplying cylinder 

air directly to the facepiece. 

There are two general categories of SCBA: 

open circuit and closed circuit. Devices in 

both categories are available that operate in 

the demand mode. As described above, the 

demand mode of operation is the least 

protective of all the modes of operation 

available. NRC advises against the use of 

demand SARs and SCBAs by assigning them 

relatively low APFs in Appendix A to 

10 CFR 20. Since demand devices look much 

like pressure-demand devices, individuals 

might perceive them to be more protective 

than they really are and attempt to use them in 

situations in which a device with a much 

higher APF is needed. The NRC requires that 

fire brigades at nuclear power facilities 

operating prior to January 1, 1979, be 

equipped with full-facepiece, positive-pressure 

SCBAs (10 CFR 50, Appendix R, 

Section II.H). Also, ANSI specifically 

prohibits the use of demand SCBA in 

emergency situations such as fire fighting. 

Little additional information is provided in 

this document about demand-mode SCBA. 

4.7.2 Open-Circuit, Pressure-Demand 

SCBA 

In an open-circuit, pressure-demand SCBA, all 

the breathing gas is carried on the back of the 

wearer. Exhaled air is expelled from the 

device through the exhalation valve on the 

facepiece. The combination of spring tensions 

in the regulator and in the exhalation valve 

cause a pressure greater than ambient to be 

maintained inside the facepiece at virtually all 

times during the inhalation-exhalation cycle. If 

a small air leak occurs in the system, or if the

NUREG/CR-0041, Revision I 39
Figure 4-16. Open-circuit, pressure-demand 

SCBA. 

face-to-facepiece seal is disrupted or 

compromised, a sufficient pressure and 

volume of air exists in the cylinder to maintain 

a positive pressure inside the facepiece. The 

wearer will be aware of the leak because the 

regulator will be passing air continuously into 

the facepiece. Thus, even with a significant air 

leak, the device is likely to continue to provide 

a high level of protection to the wearer during 

egress. Figure 4.16 shows an open-circuit, 

pressure-demand SCBA in use. 

In case of a regulator malfunction, a valve 

under the control of the wearer can be opened 

that causes air from the cylinder to bypass the 

regulator and be delivered directly to the 

facepiece. This changes the mode of operation 

to constant flow, and the air in the cylinder 

will be rapidly depleted. This emergency 

bypass capability, however, is designed to 

provide sufficient air to the wearer to permit 

escape from a hazardous environment without 

removing the facepiece. 

The weight of most SCBAs may make them 

unsuitable for strenuous work, and their bulk 

may make them inappropriate for use in a 

constricted space. The limited service life makes 

them unsuitable for routine use for long 

continuous periods, though airline-SCBA

combination devices (described below) resolve 

this limitation. The relatively short service life 

of open-circuit type devices may limit them to 

use where the wearer can go conveniently and 

quickly from a hazardous atmosphere to a safe 

atmosphere to change the tank of air. A supply 

of extra air cylinders is usually necessary, and a 

means of refilling the tanks must be available. 

This adds to the operating expense. 

The rated duration of use for these devices can 

be misleading. Since NIOSH rates these 

devices as 15-minute, 30-minute or 60-minute 

duration using a relatively low breathing rate, 

actual use time in a stressful situation or while 

performing heavy work may only be about 

50% of the rated duration. If leakage occurs or 

if the face-to-facepiece seal is seriously 

compromised, the useful duration will be even 

shorter. A warning alarm is activated when 

this device reaches 20% of full capacity, 

reminding the user to exit the area to replenish 

the air supply. The wearer should exit the area 

as soon as the alarm sounds. 

Recent changes made to the National Fire 

Protection Association (NFPA) specifications 

for open-circuit pressure-demand regulators 

make it much less likely that devices that meet 

the NFPA standard can be over-breathed. 

4.7.3 Advantages and Limitations of Open

Circuit Pressure-Demand SCBA 

Table 4-16 summarizes the major advantages 

and limitations of open-circuit pressure

demand SCBA. These devices all utilize full 

facepieces as the respiratory inlet covering. 

4.7.4 Open-Circuit SCBAs with a Donning 

Switch 

There is a type of hybrid SCBA available that 

incorporates a so-called "donning switch" into 

its design. These are designed to operate in 

demand mode during donning and while 

removing the facepiece in a safe area. The

NUREG/CR-0041, Revision I 40
Table 4-16. Advantages and limitations of full-facepiece, open-circuit, pressure-demand SCBA.

Advantages

"* No better protection available 

"* Less complicated operation and maintenance than 

closed-circuit, positive-pressure SCBA 

"* Highest APF available (10,000) 

"* Permitted for use in unassessed environments, fire 

fighting, IDLH 

"* Allows comparatively free movement over an 

unlimited area 

"* Less expensive than closed circuit SCBA 

"* Requires less maintenance than the closed-circuit 

type

donning switch in the demand mode prevents 

the rapid loss of air from the SCBA cylinder 

when the facepiece is not sealed to the 

wearer's face. After the wearer puts on the 

facepiece and is ready to enter the hazardous 

area, the donning switch is changed to the 

pressure-demand position and the regulator 

begins to operate in the pressure-demand 

mode. There are two potential problems with 

this type of device. The wearer will not have 

the benefit of a highly protective pressure

demand device if (1) the switch is mistakenly 

left in the donning position when the wearer 

enters a hazardous area or, (2) the switch is 

inadvertently or accidentally changed to the 

donning position while the worker is in a 

hazardous area. 

Licensees who have demand-only SCBAs, or 

SCBAs with donning switches, especially 

those who might need to use them in a fire 

fighting application, should be aware that 

these devices do not meet the current NFPA 

standards.4 These devices should either be 

modified to bring them up to the new standard 

or be replaced. 

4 National Fire Protection Association, "Open 

Circuit Self-Contained Breathing Apparatus for 

Fire Fighters," ANSI/NFPA 1981, 1997 edition.

-4 Limitations

"* Expensive 

"* Actual service life may be only 50% of 

rated duration 

"* Extra air cylinders needed 

"* Source of high-pressure air needed 

"* Bulk and weight 

"* Unsuitable for routine use for long 

continuous periods 

"* Relatively short service life 

"* Open-circuit SCBA are more expensive 

to purchase than supplied air systems

4.7.5 Closed-Circuit Positive Pressure 

Mode 

There is a second type of SCBA that operates 

in the "closed-circuit" (or "re-circulating") 

mode, meaning that exhaled air is retained in 

the system by use of a second hose attached to 

the facepiece. This second hose directs 

exhaled air into the back-mounted apparatus 

where the CO 2 is removed, 02 is added, and 

the treated air is made available to be re

breathed by the wearer. 

A closed-circuit positive-pressure SCBA (RP) 

is not a true pressure-demand device. Air 

exhaled by the wearer passes through a 

catalyst bed in the backpack that removes 

C02, and is directed into a spring-loaded 

breathing bag that pressurizes it to some 

extent. 02 from a pressurized cylinder in the 

backpack bleeds slowly into the breathing bag, 

re-oxygenating the air and increasing the 

pressure in the closed system. When the 

wearer inhales, the slightly pressurized air 

from the spring-loaded breathing bag provides 

the air. The oxygen bleed quickly increases the 

02 concentration in the breathing gas to 

greater than 35%. This makes these devices 

useful in applications such as high altitude 

work, or work in low atmospheric pressure 

environments that are oxygen deficient.

NUREG/CR-0041, Revision I

Full-Facepiece Open-Circuit Pressure-Demand SCBA

41
Since these devices were developed for mine 

rescue, long use times were essential. Unlike 

open-circuit SCBAs, if a closed-circuit device 

is rated for four hours, then a full four hours of 

use can be expected. These devices have also 

been adapted for use under water, primarily in 

military applications. 

If an air leak occurs in the system, or if the 

face-to-facepiece seal is disrupted or 

compromised, the small volume of pressurized 

air in the breathing bag will quickly reach 

ambient pressure. The 02 cylinder will begin 

venting into the breathing bag at a faster rate 

in an attempt to maintain system pressure, but 

if the leak is persistent, or very large, the 

device will quickly revert to the negative 

pressure mode of operation. The first sign the 

wearer might have of trouble could be the 

premature sounding of the low-oxygen 

warning alarm at 20% of capacity. The 

chemical reaction that removes CO 2 also 

increases the temperature of the air supplied to 

the wearer, which some users report is 

uncomfortable. 

These devices also require more maintenance 

between uses than open-circuit devices, even 

if the same person is going to reuse it. The 

catalyst bed in the backpack has to be replaced 

after each use, and a pressurized oxygen 

cylinder, also inside the backpack, must be 

replaced. Therefore, a supply of catalyst 

material and a number of compressed oxygen 

cylinders must be maintained on site, and a 

local source for breathing-quality oxygen 

located.

4.7.6 Advantages and Limitations of Full

Facepiece, Closed-Circuit, 

Recirculating Positive-Pressure 

SCBA 

Table 4-17 summarizes the major advantages 

and limitations of full-facepiece, closed

circuit, recirculating positive-pressure SCBA. 

Table 4-17. Advantages and limitations of full

facepiece, closed-circuit, recirculating positive

pressure SCBA.

4.8 Combination Devices 

4.8.1 Air-Purifying/Supplied-Air 

Combinations of two (or conceivably even 

more) types of respirators are possible. One 

such device is a combination air-purifying 

respirator and airline-supplied respirator. 

When the device is connected to an air supply, 

the wearer breathes the remotely supplied-air 

usually in the continuous-flow mode of 

operation. When the air supply is 

disconnected, the wearer breathes ambient air 

through an attached filter and the device 

operates in the negative-pressure mode. (See 

Figure 4-17.)

NUREG/CR-0041, Revision I

Full-Facepiece Closed-Circuit Recirculating 

Positive-Pressure SCBA 

Advantages Limitations 

"* Very long 0 Breathing air becomes 

use times warm during use 

"* Highest APF * Bulk: 2 hoses attached 

available to facepiece 

(10,000) 0 Weight 

* Require more 

maintenance between 

uses than open-circuit 

* Supply of compressed 

oxygen cylinders 

needed 

* Source for breathing

quality oxygen needed 

* Supply of CO 2 

absorbent needed

42
4.8.2 Supplied-Air/Short-Duration SCBA 

Another combination is an airline-supplied 

respirator and self-contained breathing 

apparatus. This device allows the wearer to 

breathe air from a remote supply, but provides 

a 5- or 10-minute reserve air supply in a small 

cylinder, usually attached to the wearer's belt. 

If the device operates in the continuous-flow 

mode, the only way for this device to be used 

is for the wearer to enter the contaminated 

environment, perform the required work, and 

exit the area breathing air through the attached 

airline. The attached air cylinder would be 

employed only for escape in the event that the 

airline supply failed. The cylinder should be 

charged to a minimum of 90% of its full 

capacity prior to its use. 

For pressure-demand devices with escape 

cylinders, if the use of the airline for entry and 

exit is not practical, the RPA may permit the 

wearer to enter a contaminated environment 

using the air in the belt-mounted cylinder, then 

connect to an airline supply at the work 

location. The air remaining in the cylinder is 

available for use during egress or in case the 

remotely supplied-air source fails. The RPA 

should ensure that the air expended during 

entry does not exceed 20% of the rated service 

life of the SCBA, and that the cylinder is 

charged to a minimum of 90% of its full 

capacity prior to its use. (See Figure 4-18.) 

4.8.3 Supplied-Air/SCBA 

For applications where very long work times 

are required and exiting an area in case of air 

supply failure is not an option, a standard 30

minute or 60-minute SCBA might be 

combined with an airline-supplied respirator. 

For example, in the event of a casualty, the 

atmosphere inside the control room at a 

nuclear power plant might require the use of 

supplied-air respirators. A combination 

SAR/SCBA provides maximum protection 

over a long period of use. These combination

Figure 4-18. Combination pressure-demand 

airline and short-duration SCBA.

43 NUREG/CR-0041, Revision I
devices operate in the pressure-demand mode 

while in both configurations. 

4.8.4 NIOSH Certification 

Each combination device must be NIOSH 

certified. Each device is issued only one 

certification number, and that number is for 

the mode of operation that provides the least 

protection. The NIOSH certificate, however, 

will contain information about both modes of 

operation, and the device is certified for use in 

both modes of operation. 

An exception to this certification number 

policy is that devices that include SCBA 

capability are assigned a certification number 

for SCBA. All combination devices must be 

used within the limitations stated in the 

NIOSH certificate. More information about 

NIOSH approvals is contained in Section 4.9 

below. 

4.8.5 Assigned Protection Factor 

The Assigned Protection Factor applied to a 

combination device by the licensee should be 

for the respirator type and mode of operation as 

listed in Appendix A to 10 CFR 20. If this is 

not practical, licensees may apply the smaller 

APF for the entire duration of respirator use. If 

this would result in a dose assignment, post

exposure bioassay measurements may be 

made to quantify any actual intake. 

4.9 The Role of NIOSH in Respirator 

Programs 

The NRC, OSHA and EPA all require that 

NIOSH-approved equipment be used, when 

available, as part of a compliance respiratory 

protection program. The National Institute for 

Occupational Safety and Health (NIOSH) was 

established in 1971 by the Occupational 

Safety and Health Act. The respirator 

certification work that NIOSH performs is a

direct offshoot of the approval of mine rescue 

breathing apparatus formerly done by the 

Bureau of Mines. Up until July 10, 1995, 

NIOSH tested and certified respiratory 

protection devices against the requirements of 

30 CFR 11, and all NIOSH certifications were 

issued jointly with the Mine Safety and Health 

Administration (MSHA). On that date, the 

requirements for certification of respirators 

were moved from 30 CFR 11 (Mine Safety 

and Health Administration) to 42 CFR 84 

(Department of Health and Human Services). 

Now most certifications are issued solely by 

NIOSH, a part of the Centers for Disease 

Control (CDC), which is part of the 

Department of Health and Human Services 

(DHHS). The Mine Safety and Health 

Administration (MSHA) still exists, regulates 

mining activity, and continues to issue joint 

respirator approvals with NIOSH for devices 

used in mine rescue and other mine 

emergencies, although MSHA's logo no 

longer appears on the approval label. 

4.9.1 Assigned Protection Factors (APF) 

The instantaneous protection factor (PF) of a 

respirator can defined as: 

PF= Ambient Airborne Concentration 

Concentration Inside Respirator 

The assigned protection factor for each type of 

device is based on measured PFs achieved by 

a number of individuals under work-like 

conditions with a safety factor applied. 

Presumed particle removal efficiency (%) 

based on APF can be calculated as follows: 

RemovalEfficiency(%) = 100 I pF) 

See the discussion of APFs in section 3.6.1 of 

this Manual. 

Particle removal efficiencies, provided by 

respirators having various APFs, are shown in 

Table 4-18 below.

NUREG/CR-0041, Revision 1 44
Table 4-18. Particle removal efficiencies for 

various assigned protection factors. 

Assigned Minimum 

Protection Particle Removal 

Factor Efficiency 

(APF) (%) 

10 90 

25 96 

100 99.0 

1,000 99.9 

3,333 99.97 

10,000 99.99 

Approximately 1/3 of tritium (

3H) in gaseous 

(3H2) or vaporous (120) form is absorbed 

through the skin of an exposed person, so 

intake is not limited very effectively by using 

respiratory protection devices. Air-purifying 

respirators equipped with particulate filters are 

not effective against any gases or vapors. Even 

the protection provided by supplied-air 

respirators is dramatically reduced. See 

Table 4-19 below. Calculation of these APFs 

are provided in Appendix B of this document. 

Table 4-19. APFs for supplied-air respirators 

against tritium. 

APF Tritium APF 

10 2.5 

25 2.78 

100 2.94 

1000 2.997 

10,000 3.0 

NIOSH recommends APFs for respirators 

certified under 30 CFR 11 in its "Guide to 

Industrial Respiratory Protection" and in the 

"Respirator Decision Logic." Other APFs can 

be found in ANSI Z88.2-1992. Assigned 

protection factors that are to be used against 

specific hazards can be found in Appendix A 

to 10 CFR 20 (radioactivity), 29 CFR 1001 

Table I (asbestos), 29 CFR 1910.1025 Table 2 

(lead), 29 CFR 1910.1028 Table I (benzene),

and other hazard-specific standards. No APFs 

are given in OSHA's main respiratory 

protection regulation (29 CFR 1910.134). 

NRC licensees are required to use the APFs 

provided in Appendix A to 10 CFR 20 for 

exposures to airborne radioactive material. 

When non-radiological airborne hazards are 

present, licensees should use APFs that are 

appropriate to the hazard, not (necessarily) 

those listed in Appendix A to 10 CFR 20. 

4.9.2 The NIOSH Approval Process 

NIOSH approves entire assemblies, not 

individual components of respiratory 

protection systems. Therefore, there is no such 

thing as an "approved" regulator, an 

"approved" facepiece, or an "approved" filter. 

Components are only "approved" in so far as 

they are part of a complete, approved 

assembly. A respirator manufacturer seeking 

NIOSH approval would submit samples of the 

device along with drawings, user instructions, 

and other documentation, such as its QA 

program and the QC plan for the specific 

product. NIOSH would then test the devices in 

its laboratory against the requirements of 

42 CFR 84. If the device met all the 

requirements, an approval number would be 

assigned. 

NIOSH also has a follow-up surveillance 

program, including site audits of the 

manufacturer's facilities. They also obtain off

the-shelf devices, periodically for re-testing. 

There is also a problem-investigation program, 

in which reports of problems received from 

regulatory agencies, labor organizations, 

respirator users, and respirator manufacturers, 

are investigated and resolved. Items of major 

interest or significance are widely distributed 

as "Respirator User Notices" or "Respirator 

User Warnings." 5 

5 The most current NIOSH 

User Notices are available at 

<http://www.cdc'gov/niosh/usersntc.html>.

NUREG/CR-0041, Revision I 45
Table 4-20. NIOSH approval categories. 

42 CFR 84 Approval 

Device Schedule Current 

Type Sub-Part Revision 

SCBA H TC-13F 

Gas Masks I TC- 14G 

Supplied . TC-19C 

Air 

Non- K TC-84A 

Powered 

Air 

Purifying, 

Particulate 

Chemical L TC-23C 

Cartridge 

KK TC-21 C* 

Dust, Fume, K C2C 

and Mist; (Grand- (particulate) 

andtiist; fathered TC-23C* 

Peide Spray approval (Combination 

Paint Spray schedule) or chemical 

cartridge) 

Powered KK TC-2 IC 

Air- (particulate) 

TC-23C Purifying (Combination or High ceia 

Efficiency chemical 

Respirators cartridge) 

* None issued after July 10, 1998

The NRC, OSHA and EPA all require that 

NIOSH-approved equipment be used when 

available, as part of a compliant respiratory 

protection program. NRC, when requiring use 

of NIOSH-approved devices as part of a 

respiratory protection program, is simply 

employing an equipment testing and 

certification mechanism that is already in 

place. 

NIOSH tests and approves respirators in the 

categories listed in Table 4-20. As stated 

above, if a submitted device meets the listed

criteria, it is granted a "TC" number. (The 

letters TC were originally "TCL" and stood 

for Testing and Certification Laboratory, 

Bureau of Mines. It was soon shortened to 

"TC"-Testing and Certification. The current 

official name of the NIOSH lab is the 

Certification and Quality Assurance Branch, 

Division of Respiratory Disease Studies, 

NIOSH.) 

Formerly, negative-pressure air-purifying 

respirators were accompanied by a booklet 

containing a NIOSH approval certificate for 

each combination of facepiece and filter that 

the manufacturer offered. Under the new 

scheme, NIOSH has revised its approval label 

(which is usually an 81/2" x II" sheet of 

paper), and will issue multiple approval 

numbers for a facepiece and each of the filters 

or cartridges it is approved with, all on one 

label. The list of approved assemblies on the 

label was formerly a narrative paragraph, but 

will now be a matrix list. The approval label 

enclosed with a facepiece will list all the 

cartridges and canisters that may be used with 

the facepiece. The label on a box of cartridges 

will list all the facepieces for which the 

cartridge is approved. This matrix method is 

intended to be more user-friendly. 

4.9.3 Approval of Combination Devices 

Combination devices are those which 

incorporate two modes of operation into one 

device. These are usually issued an approval 

number for the less protective mode of 

operation. For example, a combination air

purifying and supplied-air continuous flow 

respirator would be issued an approval number 

beginning TC-84A (i.e., a particulate, non

powered air-purifying respirator approval). 

Such devices are also approved for use in the 

other mode of operation, but this may not be 

apparent to the end user, who should rely on 

information from the manufacturer. Apply the 

assigned protection factor (APF) for the mode 

in which the device is operated. In this 

example (in an NRC program), APF= 100

NUREG/CR-0041, Revision 1 46
when used in the air purifying mode, and 

APF= 1,000 when used in the constant-flow 

supplied air mode. Under the new method of 

approval, any combination device that 

includes a particulate filter since July 10, 1995 

has been assigned a TC-84A approval number. 

The exception to the rule is the combination 

SCBA-supplied air respirator (SAR). These 

are certified, and assigned an approval number 

as a self-contained breathing apparatus. There 

must be no confusion about what an SCBA is 

approved for. 

4.9.4 What NIOSH Does Not Approve 

NIOSH does not approve a variety of 

equipment that is (or could be) used in 

conjunction with respiratory protection 

equipment. Examples of these would be: 

"* Breathing air distribution manifolds; 

"* Breathing air compressors; 

"* Breathing air-purification systems; 

"* Qualitative and quantitative fit test 

equipment; and 

"* Supplied air suits. 

If an approval schedule for a type of 

equipment does not exist in 42 CFR 84, then 

no approval can be granted. In the case of 

breathing air compressors, air supply systems, 

distribution manifolds, etc., the RPA should 

still ensure that Grade D breathing air or better 

is delivered to the NIOSH-approved device. 

4.9.5 Proper Use and Maintenance of 

Approved Devices 

Purchase of NIOSH-approved equipment is 

only the first step. The licensee should keep it 

in "like new" condition while allowing for a 

reasonable amount of wear. The old regulation 

stated [30 CFR 11.2(a)]: "Respirators, 

combinations of respirators, and gas masks 

shall be approved for use in hazardous 

atmospheres where they are maintained in an 

approved condition and are the same in all 

respects as those devices for which a

certificate of approval has been issued under 

this part." This paragraph was deleted from 

42 CFR 84 because NIOSH has no authority 

to regulate end users of the equipment. 

NIOSH relies on the regulatory agencies that 

oversee respiratory programs to have adequate 

requirements in place to ensure that respirator 

users are issued high-quality working 

respiratory protection devices. This means that 

these devices should be inspected before and 

after each use, and that an experienced person 

should perform required repairs, determine 

which devices are excessively worn or broken, 

and repair or discard them. A few key 

inspection points are listed below. Additional 

information about inspecting respiratory 

protection systems should be available from 

the device manufacturer. 

"* Straps should not show any breaks, 

excessive wear or loss of elasticity; 

"* Broken or malfunctioning buckles should 

be replaced; 

"• Facepieces should not show excessive 

wear, craze lines, cracks, tears, or holes; 

"* Continued use of an elastomeric facepiece 

that is distorted from improper storage 

should not be permitted; 

"* Cracked or badly scratched lenses should 

be replaced; 

"* Incorrectly mounted lenses that distort the 

facepiece should be adjusted; and 

"* Broken or missing mounting clips, 

cracked or broken cartridge holders, 

components with badly worn threads, and 

missing gaskets should all be replaced 

before the respirator can be used again. 

Where specific guidance from NIOSH does 

not exist, licensees should use, maintain, and 

repair respiratory protection devices in 

accordance with the manufacturer's 

instructions. 

Most repairs can be accomplished by a person 

who is familiar with how the device is 

constructed and who is experienced in the use 

of devices of the type to be repaired. 

Manufacturer-provided training is not required 

for the less complex portions of respiratory 

protection systems such as facepieces. Repair

NUREG/CR-0041, Revision 1 47
of some portions of pressure-demand supplied 

air respirator regulators, and several self

contained breathing apparatus components 

(e.g., regulators, alarm devices, cylinder 

valves, and possibly others) require 

manufacturer-certified training. These critical 

subassemblies are clearly identified in each 

manufacturer's literature. 

When delivered, each NIOSH-certified device 

is usually accompanied by an approval label 

and an instruction manual. As stated above, 

the label contains a matrix showing all the 

components of the approved device. The 

instructions may include an exploded drawing 

that shows all the parts in the assembly along 

with their relative locations. Replacement and 

repair parts for a device should be ordered 

from this list, even if parts that appear to be 

identical are available from another source. 

The simple fact, for instance, that a filter 

cartridge or a gasket from one manufacturer's 

respirator fits on or in the facepiece of a 

different manufacturer, does not mean that it 

should be used. 

If questions arise about which repairs may or 

may not be done in-house, about how the 

equipment is to be operated or stored, or about 

other technical matters, the best source of 

information is the manufacturer of the device. 

Reputable manufacturers should be willing to 

put their answers or explanations in writing. 

Manufacturers do not have the authority, 

however, to allow operation of their 

equipment outside the parameters stated in the 

NIOSH approval. 

The 30 CFR 11 approval labels all contained 

cautionary statements such as: 

"* Not for use in atmospheres containing less 

than 19.5% oxygen; or 

"* Not for use in atmospheres immediately 

dangerous to life or health. 

The new 42 CFR 84 labels contain an 

expanded list of these statements. For 

example:

"* Use only the pressure ranges and hose 

lengths specified in the User's 

Instructions; 

"* Failure to properly use and maintain this 

product could result in injury or death; 

"* Never substitute, modify, add, or omit 

parts. Use only exact replacement parts in 

the configuration as specified by the 

manufacturer; or 

"* Refer to User Instructions and/or 

maintenance manuals for information on 

use and maintenance of these respirators. 

4.9.6 Form, Fit or Function 

Another way in which respirators might 

potentially be misused and have their 

performance degraded involves the use of 

other types of protective, safety, or 

communications equipment in conjunction 

with the respiratory protection equipment. 

Regarding each such item, the following 

question must be asked: "Does use of this 

equipment affect or change the form, fit, or 

function of the respirator?" If the answer is "yes," then use of the device in question will 

probably result in a non-approved assembly. 

For example, use of a non-manufacturer

supplied voice amplification device, in which 

the microphone and connectors attach to or 

through the facepiece body or lens (and thus 

change the form of the respirator), would 

result in a non-approved assembly. A similar 

device, however, which utilizes a throat 

microphone, and is not attached in any way to 

the respiratory device, would be permitted 

even if it is not supplied by the respirator 

manufacturer, because the respirator is not 

directly affected. 

Anything that intrudes into the area where the 

respirator seals against the face will affect the 

fit of the device. This includes hair, cosmetics, 

standard spectacle temples, etc. A bone

conduction microphone held tight to the top 

of the head by the facepiece harness would 

also alter the fit of the respirator, and would

NUREG/CR-0041, Revision I 48
therefore not be allowed. Obviously, 

modification of any respiratory device in any 

way, except that done in accordance with the 

manufacturer's instructions, is likely to impact 

the NIOSH approval. 

A minor exception to this involves the 

marking of respirators for purposes of 

accountability. The use of small numbered 

metal or plastic tags, attached to facepieces 

with plastic electrical fasteners or small metal 

S-hooks, present no problem as long as the tag 

does not interfere with the proper operation of 

the respirator. The "D" rings normally found 

on facepiece buckles are acceptable mounting 

points. Use of bar-coded labels applied to the 

lenses of full facepieces might be acceptable if 

they do not distract or obscure the vision of 

the wearers. Methods of marking which 

damage or weaken the respirator (e.g., 

branding a number into a facepiece or lens 

with a soldering iron) are not permitted. 

4.9.7 Other Ways in Which Devices Might 

Be Misused 

Air-supplied devices must be used with air 

that meets (as a minimum) the Grade D 

requirements of the Compressed Gas 

Association (CGA) as described in their 

Pamphlet G-7.1-1997 "Commodity 

Specification for Air." This requirement holds 

for airline-supplied devices and for SCBA. 

Each airline-supplied device is approved for a 

certain minimum and maximum hose length, 

which is measured from the air distribution 

manifold to the inlet of the regulator assembly 

on the facepiece or on the wearer's belt. Such 

devices may be approved for various supply

hose lengths up to 300', with no section 

shorter than 25'. Specific devices might be 

approved for less than 300', and may have 

other limiting conditions or requirements 

added. Specific minimum and maximum air 

pressures supplied to the device are also part 

of the NIOSH approval. Formerly, all the 

different combinations of hose length and

supply pressure were listed on the approval 

label. Under the 42 CFR 84 approval method, 

the user will be referred to the manufacturer's 

instructions. Use of supply hose outside the 

approved range of lengths, or in an 

unapproved configuration, or at pressures 

outside the manufacturer's specifications is 

not permitted. 

NIOSH approvals do not address the 

maximum length of hose from a primary air 

supply up to the point where the approved 

assembly is attached to it. Therefore, breathing 

air may be connected from a supply header or 

a bank of cylinders to the inlet of a distribution 

manifold using commercially available rubber 

hose and hose clamps, or threaded pipe and 

fittings. None of this has to be supplied by the 

respirator manufacturer, or meet any NIOSH 

approval criteria. The NIOSH approval starts 

where the approved respiratory protection 

device attaches to the air distribution 

manifold. The pressure at that point must be 

within the range specified in the 

manufacturer's user instructions. 

4.9.8 Conclusion 

Just because a respiratory protection device 

has a NIOSH approval doesn't necessarily 

mean that it will be the right device for a 

particular application. Respirator program 

administrators are strongly advised to obtain 

samples of devices they want to consider for 

purchase. These should be used in the 

workplace for a period a time and subjected to 

actual conditions of use. Some respirator 

wearers should participate in the evaluation of 

devices. 

This evaluation should include an assessment 

of the ease of maintenance and other factors 

that are important in a well-run respiratory 

protection program. Performance of these 

devices should be evaluated when they are 

used in conjunction with other types of 

protective equipment. How does the respirator 

manufacturer address spectacle adapter kits?

49 NUREG/CR-0041, Revision I
Does the inside of the lens fog badly when 

used in a cold environment? Can a hard-hat be 

worn properly at the same time the respirator 

is being worn? How is voice amplification 

addressed by the manufacturer? 

4.9.9 Input to NIOSH 

Licensees should report any significant 

respirator defect or failure to the manufacturer, 

with a copy or supplemental phone call to 

NIOSH. Names and addresses of respirator 

manufacturers are available in the NIOSH 

Approved Equipment List. NIOSH may be 

contacted at: 

NIOSH Division of Safety Research 

Testing and Certification Branch 

944 Chestnut Ridge Road 

Morgantown, WV 26505 

(304) 291-4361. 

4.10 Non-NIOSH-Certified Equipment 

4.10.1 Exemptions for Non-NIOSH-Certified 

Devices 

If a licensee identifies the need for a 

respiratory protection device that is not 

NIOSH approved and not listed in Appendix 

A to 10 CFR 20, and where no such NIOSH

approved device is known to exist, the 

licensee may make application to the 

Commission to use a non-approved device. 

Commission approval is required whether or 

not APF credit will be used. The application 

should include the following information: 

"* An explanation of why no existing 

NIOSH-approved device meets the 

licensee's need; and 

"* Evidence that the material quality and 

performance characteristics of the 

proposed device are capable of providing 

adequate respiratory protection to the 

wearer under the proposed conditions of 

use while not subjecting the wearer to

undue physical or psychological stress, or 

to undue hazard. 

Such test information may be developed by 

the licensee, the equipment manufacturer, or 

by a reliable third party. The manufacturer of 

such a device should have previous experience 

with the design and manufacture of respiratory 

protection equipment. The licensee-applicant 

may use such devices under controlled 

circumstances to develop information for the 

exemption application. 

Where an exemption for use of such a device 

has already been granted to a licensee by the 

Commission, subsequent applications by 

additional licensees may make use of test 

information previously submitted. At a 

minimum, for devices that have not yet been 

granted an exemption by the Commission, the 

licensee-applicant should be involved in at 

least one operational test of the device. 

4.10.2 Radioiodine Canisters 

The NRC has granted an exemption to a 

number of power reactor licensees to use an 

APF of 50 when using combination 

particulate/organic vapor chin-mounted 

canisters in areas where airborne radioiodine 

is present (see Figure 4-19). Licensees 

receiving such authorization were required to 

establish a more stringent quality assurance 

program and procedures for using these 

canisters. Although the APF for full-facepiece 

air-purifying respirators went from 50 to 100 

in the 1999 revision of Appendix A to 10 CFR 

20, licensees previously granted this 

exemption may still only utilize an APF of 50 

for these radioiodine canisters, unless 

authorized in writing by the NRC to increase 

it. The granting of a blanket exemption by the 

NRC to all licensees to allow the use of an 

APF for these canisters against airborne 

radioiodine vapors is not anticipated. 

A few licensees who have obtained the NRC's 

authorization to use this APF have reported 

small radioiodine uptakes in wearers of this

NUREG/CR-0041, Revision 1 50
Figure 4-19. Full-facepiece respirator with 

radioiodine canister attached. 

device. It has been postulated that the reason for 

this might be the stress that such a canister 

places on the facepiece seal when the wearer 

moves about in the work place. Consideration 

should be given to using these "iodine canisters" 

during quantitative fit testing (QNFT) of 

individuals to determine whether the added 

weight of the canister has any effect on the 

quality of the fit. 

4.10.3 Supplied-Air Suits 

One-piece and two-piece supplied-air suits are 

permitted for use in nuclear industry 

respiratory protection programs, but no 

protection credit may be taken except as 

described in 10 CFR 20.1705, "Application 

for use of higher assigned protection factors." 

Additional information about this application 

is provided in Regulatory Guide 8.15, 

Revision 1. The NRC believes that, in certain 

nuclear industry applications (e.g., control-rod 

drive removal at boiling water reactors), these 

suits might be the best overall choice, taking 

into account respiratory protection, 

contamination control considerations, heat 

stress, and ALARA. 

All requirements of the respiratory protection 

program apply to the use of these devices 

(e.g., medical screening, training, air quality,

maintenance and QA requirements) whether or 

not an APF is used. 

4.10.4 Past Use of Uncertified Devices 

As a general rule, use of non NIOSH-certified 

devices is not permitted in an NRC-regulated 

respiratory protection program. The NRC is 

aware that, in the past, a few licensees have 

deliberately used non NIOSH-approved 

disposable dust masks for certain tasks in an 

attempt to avoid medical screening, training, 

and/or fit testing requirements. The removal of 

the medical screening and fit testing 

requirements for the use of filtering facepieces 

without using an APF, and the minimal training 

now required for users of these devices, should 

give licensees the program flexibility necessary 

to maintain full compliance without imposing 

unnecessary burdens for a large number of 

workers. 

4.11 Inventory, Inspection, and Storage 

4.11.1 Facepieces 

Each time a respirator goes through the 

decontamination-sanitization cycle, the 

facepiece should be inspected and tested for 

gross leakage before being made available for 

reissue. The inspection and testing should be 

done by a person who is trained to perform 

this procedure, and who is approved by the 

RPA. Each component of the facepiece should 

be examined for presence and proper function. 

As a final check, any of the following methods 

may be used: 

"* The person doing the testing performs a 

user seal check, then re-sanitize the 

facepiece. This re-sanitization could 

utilize a non-alcohol wipe or a sanitizing 

spray; 

"* Perform a leak test using a test head and 

aerosol generator; 

"* Perform a leak test using a test head and a 

vacuum pump; or

51 NUREG/CR-0041, Revision I
* Rely on the end user to perform the 

required user seal check. Consider having 

this seal check performed at the point of 

issue so a defective respirator may be 

identified and replaced immediately. 

Also see paragraph 4.12.4 below. 

Respirator facepieces that are available for 

routine issue should be visually inspected at 

least every month. If such devices are stored in 

clear plastic bags, verify that no moisture 

condensation is visible on the inside of the 

bag. A few facepieces should be handled and 

examined each month but need not be 

removed from the bags as long as the licensee 

can determine that the device is ready for 

issue. 

Respirator facepieces that are designated for 

emergency use, such as those staged at the 

Emergency Operations Center at a commercial 

power reactor facility, should be visually 

inspected at least every month as described 

above for respirators that are available for 

routine issue. A more thorough inspection 

should be conducted twice or three times per 

year where each facepiece is handled and 

inspected. Licensees should consider re

washing and re-sanitizing these emergency

use facepieces on an annual basis, or replacing 

them periodically with different facepieces 

that have been washed and sanitized more 

recently. 

At the time each facepiece is issued, the 

qualified issuing person should inspect the 

device to ensure that all component parts are 

present, that the proper filter or canister is 

attached or provided, and that the lens is free 

from significant abrasions. 

Each time a respirator is donned, the wearer 

should perform a user seal-check such as a 

positive-pressure check or a negative-pressure 

check. Respirator users must be trained to 

recognize the symptoms of a leaking facepiece 

during this seal check, and trained to obtain a 

properly working replacement prior to 

entering an airborne contamination area.

Store facepieces in a plastic, cloth or paper 

bag with straps fully extended and inside the 

facepiece. The licensee determines whether 

the filter is attached before storage or attached 

at the time of issue. The bag should be secured 

closed and contain an easily visible tag or 

sticker indicating the date the facepiece was 

last sanitized and fully inspected. The identity 

of the person who performed the inspection 

should also be indicated. Bagged full

facepieces should be stored on a flat surface, 

with the lens down. Half-facepieces should be 

stored in the same way with the support yoke 

down. Do not store facepieces with the face 

seal portion bearing the weight of the 

respirator. Do not stack respirator facepieces 

unless they are first placed in a rigid container. 

The original facepiece box is acceptable. 

Other methods of facepiece storage are 

acceptable as long as the seal area is protected 

from distortion and the device can be kept free 

of dust and dirt. 

Respirators that are ready for issue should be 

in like-new condition with allowance made for 

superficial signs of wear. 

4.11.2 Associated Equipment 

Equipment used in conjunction with 

respirators (e.g., belt/mask-mounted air 

regulators, air-supply hoses, portable 

distribution manifolds, etc.) should be 

inventoried and functionally tested 

periodically, for instance, twice yearly or prior 

to issue (licensee's choice). During this 

inspection, the licensee should verify that 

these components are clean and in ready-to

use condition, and that there are a sufficient 

number of them available to meet the needs of 

the program during high-usage periods. 

A functional test for an air hose would consist 

of connecting it to a source of breathing air, 

verifying that air flows through it, and that 

there are no leaks. An adequate inspection 

would consist of verifying that the quick

connect fittings are properly installed and

NUREG/CR-0041, Revision I 52
operate properly, and that the hose is not cut, 

nicked or abraded. Hoses should be in like

new condition. An acceptable way to store air 

hoses is in a coil with the quick-connect 

fittings connected together. This protects the 

inside of the hose from dirt and debris. Other 

acceptable methods of protecting the quick

connect fittings and the hose interior are to 

cover the ends with tape, small plastic bags or 

plastic caps. Air hoses that are ready for issue 

should be in like-new condition with 

allowance made for superficial signs of wear. 

Consider storing coils of hose inside a 55

gallon drum to protect them from damage. 

A functional test for a mask- or belt-mounted 

regulator would consist of connecting it to a 

source of breathing air and verifying that air 

flows through it. An adequate inspection 

would consist of verifying that any threaded 

connectors are in good condition, or that 

quick-connect fittings are properly installed 

and operate properly. Regulators that are ready 

for issue should be in like-new condition with 

allowance made for superficial signs of wear. 

A functional test for an elephant trunk-style 

breathing tube would consist of blocking both 

ends and stretching the tube as far as it will go. 

This will collapse the breathing tube. If the 

tube stays collapsed for 15 seconds or more it 

is unlikely to have a significant leak. Other 

methods suggested by the manufacturer are 

acceptable. 

Repair and replacement parts for respiratory 

protection devices should be inventoried and 

inspected periodically. 

4.11.3 Emergency-Use SCBA 

Emergency respiratory protection equipment 

(SCBA) should be visually inspected monthly, 

and donned and operationally tested quarterly. 

Licensees should attempt to use infrequently 

used SCBA on a rotating basis for training or 

during drills or exercises. Other respiratory 

protection devices designated for emergency 

use (e.g., single use, escape-only SCBA)

should be removed from any protective bag 

and examined thoroughly once per month. 

Filter respirators stored for emergency use are 

covered in 4.11.1 above. 

4.11.4 SCBA Cylinders 

SCBA cylinders should be inspected monthly 

to verify that they contain a minimum of 90% 

of their rated capacity. 

Regulations regarding all pressurized gas 

cylinders are the responsibility of the U.S. 

Department of Transportation (DOT). There 

are currently three types of SCBA cylinders 

available on the market: steel, aluminum, and 

composite. Steel and aluminum cylinders can 

be distinguished from composite cylinders 

because they have smooth exteriors. 

Composite cylinders consist of a relatively 

thin aluminum shell that is reinforced by 

wrapping fibrous material around the outside. 

Some composite cylinders are fully reinforced 

from neck to bottom, others have only the 

cylindrical section reinforced. This second 

category is referred to as "hoop-wrapped" 

cylinders. To date, most composite cylinders 

have been reinforced with fiberglass, but 

beginning in 1997, some have been made 

using carbon fiber reinforcement. 

Steel and aluminum cylinders must be 

depressurized, inspected, refurbished as 

necessary, and hydrostatically tested every five 

years. Composite cylinders must undergo this 

process every three years. 

Composite cylinders have a maximum life of 

15 years from the date of manufacture. After 

this, they must be replaced. It is possible that 

carbon fiber-wrapped composite cylinders 

may eventually have their useable lifetime 

extended, since there is a provision made by 

DOT that additional testing can be done after 

15 years of service. The carbon fiber-wrapping 

technology will be 15 years old in the year 

2012. Steel and aluminum cylinders may be 

used indefinitely as long as they continue to be

53 NUREG/CR-0041, Revision I
properly maintained and pass the hydrostatic 

test requirement. 

4.11.5 Equipment in Storage 

It is accepted practice to designate a certain 

number of facepieces "in storage" to avoid 

having to inspect them monthly as is required 

for ready-to-issue facepieces. This is a 

reasonable procedure so long as the devices in 

storage are effectively prevented from being 

used. This could be accomplished by covering 

portions of the normally ready-to-issue 

facepiece storage shelves with cardboard or 

plastic sheets that are clearly labeled, "Do Not 

Use." 

When in storage and not available for use, 

respirators and component parts of respiratory 

protection devices should be inspected 

annually to verify that they are stored in such a 

way as to prevent damage. Checks of items in 

storage should be performed to ensure that the 

facepiece rubber is not taking a set, that rubber 

parts are not hardening or deteriorating, that 

sorbent canisters have not exceeded their shelf 

life, and that breathing-air or oxygen cylinders 

contain sufficient pressure. These checks 

should be designed to ensure that if devices in 

storage are needed, they will be ready for use 

quickly. Devices in storage should also be 

inspected prior to being made available for 

issue. 

Equipment in warehouse storage need not be 

routinely inspected at all. This includes 

equipment that was once in use, but that has 

been repackaged in order to prevent damage 

and returned to a warehouse for storage. 

Table 4-21 below summarizes NRC's 

interpretation of the types and frequencies of 

respirator inspections. 

4.11.6 Shelf Life 

The concept of "shelf life" may not be 

appropriate for respirator facepieces, SCBA,

and related equipment. Thin rubber 

components such as inhalation and exhalation 

valves can loose their elasticity, however, and 

may need to be replaced periodically. 

Respirator facepieces have been observed to 

last for many years if properly maintained, 

cleaned and stored. One licensee reports that 

facepieces that were in service in 1981 are still 

in use. Properly maintained and stored, SCBA 

are reported to have been in service for over 

25 years. These have been maintained and 

overhauled periodically in accordance with the 

manufacturer's instructions, and have been 

upgraded as necessary to meet NFPA 

standards. At least one SCBA manufacturer 

has specified a 15-year SCBA regulator 

overhaul period for infrequently used devices. 

This is in contrast to a 3- or 5-year overhaul 

period specified for frequently used SCBA. 

The most critical factors in extending the life 

of respiratory protection equipment are: 

"* Proper water and air temperatures when 

washing, rinsing and drying the devices; 

"* Avoiding contact with harmful solvents 

and chemicals; 

"* Storage to prevent rubber components 

from becoming distorted; and 

"* Storage with no residual moisture. 

The NRC believes that a good visual and 

hands-on inspection of a respirator and its 

components will reveal which are still 

serviceable, and which need to be repaired or 

replaced. Shelf lives and other such arbitrary 

limitations on service life are better suited to 

critical components inside devices that are not 

readily available for periodic inspection. 

It might be asked why annual inspection of 

facepieces in storage is recommended at all, 

since an inspection is required before a 

facepiece is taken out of storage and made 

available for issue. It is inspected again by the 

person issuing the respirator, and the respirator 

user is required to perform a user seal check 

upon donning the facepiece. NRC does not 

recommend an extensive annual inspection of

NUREG/CR-0041, Revision I 54
Table 4-21. Summary of recommended inspection frequencies for respiratory protection devices. 

Intended Use Equipment Type Inspection Type and Frequency' 

Emergency Use or Rescue SCBA Monthly: Visual' 

Quarterly: Functional3 

After use: Functional 3

."0 

Overhaul Regulator per Manufacturer 

Emergency Use SCBA cylinders Monthly: Check Pressure 

Hoop-wound: Inspect, overhaul, hydro 3 yrs. 

Alum. and Steel: Inspect, overhaul, 

hydro 5 yrs. 

Emergency Use Elastomeric Facepieces other Monthly: Visual' 

than SCBA 2-3 times per year: Thorough'0 

Escape Only Escape-Only Devices Monthly 

Routinely Available for Use Elastomeric Facepieces 1. After use: Thorough'' 

2. Monthly: Visual4 

3. At time of issue by issuing person 

4. User seal check on donning 

Routinely Available for Use Supplied-Air Hoods or Suits' 1. At time of issue by issuing person 

2. User operational check after donning 

Routinely Available for Use Repair and replacement parts Quarterly: Visual' 

for NIOSH-certified device6 

Routinely Available for Use Air reducers, air distribution Twice per year: Functional test 7 

boxes 

In Storagee Elastomeric Facepieces 1. Before being made available for issue: 

thorough'0 

2. If in storage for >1 year: Annual visual4 

Warehouse stock' All No routine inspection required. 

Thorough inspection'0 before being made 

available for use, except hoods and suits5 . 

I Less frequent inspections are acceptable if recommended and documented by the manufacturer. 

2 Visual inspection of SCBAs should verify that all components are present, straps are adjusted to the full-out position, and the cylinder 

pressure is >90% of capacity. 

3 A functional inspection of an SCBA should include donning the device to test the operation of all buckles and straps; opening the 

cylinder valve and pressurizing the regulator; donning the facepiece to test proper head harness operation, and taking a series of breaths to 

test the operation of the regulator and exhalation valve; ensure that the low-pressure alarm activates at 20% of full cylinder pressure. Re

sanitize the facepiece, return the facepiece and apparatus straps to the full-out position, and ensure that the cylinder pressure is >90% of 

capacity. 

4 For facepieces stored in transparent bags, an adequate visual inspection would consist of ensuring that no moisture condensation was 

visible through the bag, and that the facepieces were stored in such a way as to not distort the seal area. For facepieces stored in non

transparent bags, the licensee should ensure that that they are stored in such a way as to not distort the seal area, and should examine a few 

facepieces to ensure that they are not damp. In both of these cases this is intended to be a cursory inspection. Therefore each facepiece does 

not need to be examined individually. 

5 Supplied-air hoods and suits that are still in the packaging as received from the manufacturer, need not be routinely inspected. An 

inspection by the issuing person should be done at or near the time of issue. Also, an operational performance check of the device should be 

performed after it has been donned by the wearer but before the wearer is exposed to airborne contaminants. Hoods or suits that are reused 

should be inspected prior to each use. 

6 Equipment such as belt- or facepiece-mounted pressure reducers, air supply hose, air distribution boxes, replacement parts for NIOSH

certified systems, and the like. This equipment should be clean and stored where environmental conditions are not likely to have an adverse 

effect on them. 

7 A functional test means verifying that these components operate. No measurement of pressure or flow is required. 

8 This refers to facepieces located in or near the respirator issue area, but which are covered by some type of barrier to effectively 

prevent inadvertent use or easy access, and which have been declared "out of service." 

9 Respirators that are new and still in the warehouse or in another long-term storage location need not be routinely inspected. Respirators 

that were in use at one time, but which have been properly repackaged and returned to warehouse storage, need not be routinely inspected. 

10 Examine each component of each facepiece for presence and proper function. The person doing the testing should perform a user 

seal check, then re-sanitize the facepiece. Leak test using a test head and aerosol generator or vacuum pump is also acceptable.

55 NUREG/CR-0041, Revision 1
devices in storage. It expects licensees to 

verify that stored respirators are, in fact, still 

available if needed, have not been pilfered or 

vandalized, have not been moved in such a 

way as to cause elastomeric parts to be bent or 

twisted out of shape, and that physical 

conditions in the storage area (e.g., 

temperature, humidity) are still satisfactory. 

Respirators in storage do not necessarily need 

to be removed from their containers for this 

periodic inspection. 

4.12 Maintenance Program 

4.12.1 Purpose 

Inspection, testing, and repairing of respiratory 

protection devices by competent personnel is 

an essential element in a high quality 

respiratory protection program. 

4.12.2 Qualifications of Respirator 

Maintenance and Repair Personnel 

Respirators and component parts of respiratory 

protection devices should be maintained and 

repaired only by persons specifically trained to 

perform this work. Such repairs and 

maintenance should be accomplished in 

accordance with the manufacturer's 

instructions, but training by the device 

manufacturer is not required. 

Maintenance and repair of some components 

of certain devices require manufacturer

certified training. Some examples would be 

SCBA regulators and low-pressure alarms. 

The device manufacturer specifies these 

components. 

4.12.3 SCBA Maintenance and Repair 

SCBA manufacturers specify the frequency at 

which their devices need to be overhauled and 

adjusted. Under certain circumstances, such as 

SCBAs staged for emergency use but rarely

used in fact, some manufacturers have informed 

licensees that these overhauls and adjustments 

may be performed less frequently for these 

"limited use" devices. This recommendation by 

manufacturers is consistent with regulatory 

requirements.6 

4.12.4 Facepiece Leak Tests 

Leak-testing each facepiece on a test head after 

each decontamination and inspection cycle is 

not required. A licensee can take for granted the 

quality of a respirator that is ready for issue if all 

of the following are in place: 

"* An adequate maintenance, inspection and 

repair program has been followed; 

"• The person who issues the respirator is 

qualified to recognize that the device is in 

useable condition with all component parts 

present; and 

"* The individual respirator users perform a 

seal check each time a facepiece is donned 

and are able to distinguish a properly 

operating facepiece from a defective one. 

Experience has shown that a properly 

maintained and inspected facepiece rarely 

develops significant leakage that cannot be 

identified during a user seal check. In view of 

this, the practice of mechanically leak testing 

each facepiece each time it is processed is not 

necessary and does not materially improve the 

quality of issued respirators, and is therefore not 

warranted. As a good practice licensees who 

have this equipment may choose to test some 

percentage of the facepieces coming through the 

decontamination-disinfection-inspection 

process, or they may choose to test respirators 

that have had repair work done on them before 

they are made available for issue. A user seal 

check performed by respirator maintenance 

personnel might also be considered. 

6 Letter, LeMoine J. Cunningham, Chief, Radiation 

Protection Branch, NRR to John F. Schmidt, Chief 

Health Physicist, Nuclear Management and Research 

Council, August 26, 1992.

NUREG/CR-0041, Revision I 56
New facepieces, and facepieces that have been 

returned to warehouse storage, should be 

sanitized and leak checked before being put into 

service. See Table 4-21, footnote 9. 

4.12.5 Testing Respirator Filters 

It is not required, nor is it necessary, to re

certify respirator filter efficiency prior to use. 

Respirator filter manufacturers have quality 

assurance (QA) and quality control (QC) 

programs approved by NIOSH to ensure that 

their filters or cartridges meet the certification 

criteria specified in 42 CFR 84. 

4.12.6 Reuse of Respirator Filters 

In 1983, responding to a question from 

licensees, the NRC took the position that 

respirator filters had to be tested with a 

0.3-micron, thermally generated DOP aerosol, 

and demonstrate >99.97% efficiency prior to 

use. This defaulting to the HEPA filter 

certification criteria was a conservative position 

taken, due to a lack of data on other test 

methods. Since that time, however, filter testing 

protocols with other aerosol media and/or 

generating techniques have been shown to 

provide adequate sensitivity to detect damage to 

a filter which would void its HEPA 

characteristics. Therefore, it is the NRC's 

current position that aerosol penetration testing 

of filters and canisters by licensees should be 

performed with a testing protocol capable of 

detecting significant filter damage or 

deterioration. It is not required, nor is it 

necessary, to re-certify the filter efficiency prior 

7 to use or reuse. 

Licensees who wish to reuse replaceable 

facepiece filters as described in Regulatory 

Guide 8.15, Revision I may perform the 

7 Health Physics Position-226 (HPPOS-226). The health 

physics position was written in the context of 10 CFR 

20.103, but it also applies to "new" 10 CFR 20.1703. See 

also the letter from L. J. Cunningham to S. K. Herweyer 

(TSI Incorporated) dated February' 27, 1990.

required penetration test using corn oil aerosol, 

ambient dust particles, or any other aerosol for 

which a detection system is available. Aerosol 

penetration testing of filters prior to their reuse 

is necessary to detect damage, incurred during 

prior use, that may not be evident in a visual or 

pressure drop test. 

An industrial hygienist or health care 

professional should address the issue of 

potential presence of microorganisms on 

respirator filters intended for reuse.8 

4.12.7 Equipment Calibration 

Static pressure gauges, differential pressure 

gauges, flow meters, particle detectors and other 

components of devices or test equipment used 

in a compliance respiratory protection program 

should be calibrated either annually, or as 

specified by the manufacturer, or in accordance 

with licensee procedures. 

The flow-restricting devices commonly used in 

constant-flow supplied air respirators are not 

considered to be regulators for purposes of 

periodic re-calibration. Periodic functional tests 

of these devices is adequate. 

4.13 Quality Assurance 

4.13.1 Purpose 

The purpose of quality assurance (QA) in a 

respiratory protection program is to prevent the 

use of defective or faulty devices. A proper and 

complete QA program should encompass 

inspection and/or testing of both new and used 

devices. Written procedures should be 

established to maintain uniformity of the 

program. 

8 NIOSH Respirator User Notice, May 2, 1997 

<http://www.cdc.gov/niosh/respupdt.html>.

NUREG/CR-0041, Revision I 57
4.13.2 New Equipment 

Quality assurance inspection and testing of new 

equipment is not intended to dispute the design 

but to find any instances of human error in the 

manufacture and assembly of the devices. 

Manufacturers of NIOSH-approved devices 

maintain rigid quality assurance programs for 

testing of newly manufactured devices and 

parts, but human error in testing may permit 

distribution of defective equipment. Thus, a QA 

program covering new equipment is needed. 

Facepieces 

Half-mask facepieces should be inspected to 

ascertain the following: 

"* Only half-facepieces with a 4-point 

suspension should be used; 

"* Integrity of valves and seats; 

"* Presence and integrity of cartridge 

gasket or gaskets (as required); and 

"* Integrity of facepiece (absence of 

tears, mold defects, etc.). 

Full facepieces require more attention than the 

half-facepieces, owing to the intricacy of the 

valves and speaking diaphragm assembly 

available on most. Inspection of full facepieces 

should include the following: 

"* Straps and suspension; 

"* Integrity of facepiece (absence 

of tears, mold defects, etc.); 

"* Canister or cartridge mounts 

(cheek, chin, etc.); 

"* Canister or cartridge gaskets 

(where applicable); 

"* Integrity of inhalation and 

exhalation valves and seals; 

"* Speaking diaphragm assembly 

(diaphragm, diaphragm gasket, 

assembly tightness); 

"* Lens (absence of scratches, cracks, 

blemishes); and 

"* All clamps and connections (check for 

tightness).

Where leak-test equipment is available, 

licensees may choose to test some percentage of 

new facepieces as a good practice. New 

facepieces should be sanitized before being 

made available for use. 

Cartridges, Canisters, and Filters 

Cartridges, canisters, and filters should be 

visually inspected for damage caused by 

handling and shipping. The presence of proper 

labels should be verified. 

Powered A ir-Purifying Respirators 

The facepieces on the units should be inspected 

and tested as suggested above. The blower 

should be checked for adequate airflow, and the 

corrugated breathing tube should be inspected 

for cracks or other defects and for tightness of 

connections. 

Hoods and Suits 

Hoods and suits should be checked for tears 

and defects in fabrication material, presence of 

zippers and snaps as required, and integrity of 

heat-sealed seams and air distribution and 

exhaust systems. 

Regulators 

Supplied-air regulators shall be visually 

inspected for damage, attached to an 

appropriate air supply, and tested for proper 

function. 

Compressors 

Compressors used to provide air for 

atmosphere-supplying respirators should be 

inspected and tested to ascertain the following: 

0 Proper and adequate intake filters;

NUREG/CR-0041, Revision I 58
"* Presence of moisture trap or dryer; 

"* Sufficient reserve air storage (if present); 

"* Carbon monoxide alarm presence and 

proper function (if present); 

"* Adequate air output and presence of 

proper connectors for equipment to be 

used; and 

"* Heat alarm function (if present). 

Oil-type compressors should only be used if 

fitted with either a continuous carbon 

monoxide monitor or high-temperature alarm. 

Diaphragm and water-seal pumps are 

recommended since they do not create an air 

supply contaminated with oil mist or carbon 

monoxide. Moisture criteria need to be met for 

air used to fill SCBA and other breathing-air 

cylinders. 

Airline Hose 

Airline hose should be inspected for the 

following: 

"* Contaminants (mold powder, ground 

rubber, etc.) inside the hose. 

"* Proper fittings and connections (i.e., not 

compatible with other gas or fluid 

systems); and 

"* Cuts, breaks, or weak spots in hose. 

Open-Circuit SCBA 

The self-contained breathing apparatus 

(SCBA), the most complicated of respiratory 

protective devices, requires more extensive 

inspection and testing than other types of 

devices. Owing to the intricacy of the parts of 

the SCBA, simple visual inspection is not 

sufficient to identify defective units. 

Inspection and testing of a SCBA should be 

done by individuals totally familiar with the 

particular device. 

The facepiece, corrugated breathing tube and 

connectors should be inspected as described 

above. Special attention should be given to the 

pressure-demand exhalation valve operation.

Regulators and alarms of SCBA are to be 

visually inspected and a simple test performed 

to ascertain proper regulator function and 

integrity of the regulator diaphragm. The 

alarm should be activated to ascertain that it 

functions properly. 

The following other parts of SCBA should be 

checked: 

"* Cylinder - check the pressure; check the 

cylinder valve for leaks, and inspect the 

cylinder valve lock for presence and 

function; and 

"* Backpack and harness assembly 

Inspect the integrity of straps, 

buckles, and fasteners; and check 

the backpack cylinder lock assembly 

for function. 

Closed-Circuit SCBA 

The facepiece, corrugated breathing tubes and 

connectors should be inspected as described 

above. In addition, check the following: 

"* Breathing Bag - Visually inspect for tears 

and defects, then inflate and check for 

leaks; and 

"* CO, Sorbent - Make certain that used 

sorbent is removed from the unit before 

storage. (Do not refill with sorbent until 

immediately prior to use of unit.) Ensure 

that seals on sorbent containers are in 

place. 

4.13.3 SCBA Inspection 

It is virtually impossible to inspect and test 

self-contained breathing apparatus properly 

without actually donning the unit. New units 

should be donned, straps fully adjusted, and 

used for a period of time (e.g., 10 minutes) to 

verify that they operate properly. After this 

type of test, appropriate components should be 

sanitized, the straps fully extended, and the air 

cylinder replaced with one that is fully 

charged before the unit is made available for 

use.

NUREG/CR-0041, Revision I 59
4.13.4 Inspection and Tests After 

Cleaning and Maintenance 

The procedures for inspecting and testing 

cleaned and repaired devices are the same as 

those outlined in the preceding new equipment 

section, in the equipment manufacturer's 

literature, and as described elsewhere in this 

Manual. 

4.14 Control and Issuance 

Licensees should maintain positive control 

over the issuance of all respiratory protection 

devices. Sufficient control should be 

established and maintained so that persons not 

authorized to wear such devices are effectively 

prevented from obtaining them. 

By assigning serial numbers to individual 

reusable respirator facepieces, the licensee will 

be able to find out who wore a device that is 

discovered to be defective during the 

decontamination and inspection process, and 

consider performing an internal dose evaluation. 

For disposable filtering facepiece respirators or 

dust masks with no APF assigned (see 

Regulatory Guide 8.15, Section 4.8), the NRC 

recognizes that these devices might be issued 

from sources other than a centralized respirator 

issue room. The licensee should take reasonable 

steps to see that only those individuals who 

have received the minimal required training for 

voluntary users be allowed to use these devices. 

Given the short duration of required training for 

users of these dust masks, and given that the 

medical screening and fit testing requirements 

are waived for users of these devices, licensees 

might consider providing this minimal training 

to all radiation workers. 

A respirator can be reused by the same 

individual on the same day or during the same 

work shift as long as external contamination 

levels are manageable. Licensees should take 

precautions to keep the interiors of such devices

uncontaminated. Storage in a plastic bag bearing 

the identity of the user would be adequate. 

4.15 Recordkeeping 

Records of personal fit tests, medical screening, 

training, and issuance of respirators should be 

maintained in accordance with the requirements 

of 10 CFR 20. 

Individual maintenance and repair records do 

not necessarily have to be kept on each 

respirator facepiece. The NRC does not believe 

that it is important to know on which date, for 

example, the coupling nut or exhalation valve 

was replaced on a given respirator, as long as 

each respirator is in like-new condition at the 

time of issue (see paragraph 4.1 of Regulatory 

Guide 8.15). Since little or no dose is likely to 

be saved by keeping these records, such detailed 

records are not cost-justified and therefore, not 

ALARA. A tag or sticker on the facepiece 

storage bag, containing the date of last 

inspection and the identity of the person who 

performed the inspection, is adequate 

documentation. 

Procurement information should be maintained 

in so far as it enables the licensee to accurately 

determine the correct part number to be ordered 

for the equipment being maintained. Some 

manufacturers provide "exploded" views of 

their equipment with part numbers provided for 

each. Parts of some respiratory protection 

devices look very similar but are, in fact, 

different from one another. In order to maintain 

NIOSH approval for each device, it is important 

for the licensee to be able to identify and order 

the correct parts for respirators. 

4.16 Respirators Supplied by Contractors 

Contractors may be required or permitted to 

provide their own respiratory protection 

equipment or sources of breathing air to perform 

tasks at a licensee's site. This usually occurs 

when specialized work such as sand blasting or

NUREG/CR-0041, Revision I 60
diving is to be done since the licensee may not 

maintain this type of equipment in inventory. 

The reason need not be justified. It is the 

licensee's obligation to ensure that the systems 

used are NIOSH approved (where applicable), 

and are used and maintained in such a way that 

the NIOSH approval is maintained. Breathing 

air sources must deliver Grade D or better air. If 

such equipment is to be returned to a contractor 

that does not have an appropriate radioactive 

materials license, then the equipment must meet 

licensee's criteria for unrestricted radiological 

release. If contaminated, it may be shipped to 

another appropriately licensed facility. 

It would be a rare case when contract personnel 

would need to use respirators for protection 

against airborne radioactive material at the site 

of a licensee where an NRC respiratory 

protection program is not in effect. If this 

situation were to occur, the licensee is still 

responsible to ensure that the contractor's 

program is in accordance with the requirements 

of 10 CFR 20 Subpart H. This could be 

accomplished by obtaining the services of a 

qualified consultant. 

4.17 Service Life Limitations 

NIOSH has noted9 that the efficiency of P-series 

filters (i.e., oil-proof under the 42 CFR 84 

approval terminology) may be significantly 

reduced with long-term use in the presence of 

oil aerosols. Such long-term exposure has 

resulted in the reduction in efficiency of P100 

filters to efficiencies much less than that 

required for P95 filters. In some workplace 

situations, this reduction in efficiency is not 

accompanied by an increase in breathing 

resistance that would signal the user to replace 

the filter, or filter element. Since this reduction 

in filter efficiency varies significantly from 

model to model, licensees who use respirators in 

an oil aerosol environment are encouraged to 

" NIOSH Respirator User Notice. May 2. 1997 

<http://www.cdc.gov/niosh/respupdt.html>.

contact the manufacturers of any P-type 

respirators or respirator filters that they use to 

receive guidance on filter change frequency. 

This same notice states the current NIOSH 

service-time-limit recommendations for non

powered particulate filter respirators. 

4.18 Breathing-Air Supply and 

Distribution 

4.18.1 Supply Systems 

Breathing air is usually supplied to a header by 

one or more compressors which draw air 

through an intake filter. Aln air dryer or moisture 

separator is usually incorporated to make the 

supplied air as dry as possible. Moisture inside 

an air system can cause corrosion inside pipes 

and other components. Rust particles can clog 

regulator orifices and cause other problems. In 

cold climates, moisture-laden air can also freeze 

as it is depressurized in a regulator. 

A large-volume tank called a receiver is usually 

attached to the system. The compressor 

pressurizes the receiver along with the rest of 

the header. When the system reaches its 

maximum operating pressure, the compressor 

shuts off. The receiver supplies air to the header 

until header pressure reaches its minimum 

operating pressure. At this point, the compressor 

comes on and re-pressurizes the system. See 

Figure 4-20. 

Other equipment that might be incorporated into 

an air system used for breathing air might be an 

air purification system, a CO monitor, and/or an 

02 monitor. 

NIOSH does not certify breathing-air supply 

systems, and neither NIOSH nor the NRC 

require that a dedicated breathing-air system be 

used. The only requirement imposed by NIOSH 

and the NRC is that Grade D-quality (or better) 

air must be delivered to the NIOSH-certified 

respiratory protection system.

NUREG/CR-0041, Revision I 61
Intake Filter Receiver

Figure 4-20. Typical breathing-air supply system.

4.18.2 Distribution Equipment 

At various locations along the air header, a "tee" 

and an isolation valve are installed so that air 

may be used from the header. A permanent or 

portable distribution manifold is then attached to 

the header near where supplied-air respirators 

will be used. Such a manifold usually consists 

of the following components: 

"* Particulate air inlet filter; 

"* Pressure relief valve (125 psig); 

"* One or more pressure regulators; 

"* One or more female quick-connect fittings; 

and 

"* A pressure gauge installed on the low

pressure side of each regulator. 

NIOSH does not certify distribution 

manifolds. Therefore, these may be purchased 

as a unit from a vendor, or fabricated by the 

licensee. The filter is intended to trap rust 

particles and scale that might develop inside 

steel pipes, and therefore, does not have to 

meet any particular efficiency requirements. 

NIOSH sets a maximum pressure of 125 psi 

for air supplied to an SAR, so a relief valve 

would be set to open at this pressure in a 

system that operates at greater than 125 psi. 

Vendor-supplied units are usually configured

in a compact box that looks like a suitcase. If 

fabricated by the licensee, good practice 

dictates that this distribution box be made 

using clean, high quality materials. An 

engineer should review the design to ensure 

that the component and material specifications 

are adequate to provide sufficient pressure and 

volume air flow. The NIOSH-certified device is 

attached by quick-connect fitting to this 

manifold, and the manifold regulator is set to 

the pressure range specified by the NIOSH 

certification and manufacturer's instructions. 

The hose (if any) used to connect the 

distribution box to the breathing air header is 

not restricted as far as length, diameter, 

material, type of connections and so on. The 

maximum hose length specified in the NIOSH 

certification does not apply to this hose. As with 

the components of the distribution manifold 

described above, there is no NIOSH approval 

requirement for these hoses. Good practice 

dictates that this connection be made using 

clean, high quality materials. Hoses used for this 

purpose should not be used for any other 

purpose to prevent them from becoming unfit 

for use with breathing air, and the hose 

connectors should be incompatible with other 

gas or fluid systems in the facility.

NUREG/CR-0041, Revision 1

Attachment Points

Header

. I

62
NIOSH approvals for SARs require that a 

minimum airflow be delivered to the respiratory 

inlet covering (4 cfm minimum for full 

facepieces, 6 cfm minimum for hoods and 

helmets). The certifications are written, 

however, so that the end user of the respiratory 

device is not required to measure the actual flow 

rate of air delivered to the device. Rather, an 

acceptable pressure range at the distribution 

manifold is specified for a given length of hose, 

number of hose sections, or for a specified 

number of quick-connect fittings. This works 

well when a single device is connected to a 

pressure regulator. It also works when two or 

more identical devices are connected to the 

outlet of a single pressure regulator as long as 

the hose lengths and/or number of quick

connect fittings are the same in each device. 

However, each time a device is added to a 

manifold supplied by a single regulator, the air 

pressure on the distribution manifold decreases, 

and has to be readjusted to meet the NIOSH

requirement. If two or more different devices 

are connected to the output of a single pressure 

regulator, or if the hose lengths and/or number 

of quick-connect fittings are different, it might 

be difficult (or impossible) to maintain a 

manifold pressure that meets the NIOSH 

requirement for all of the attached devices. If 

sufficient air pressure cannot be maintained to 

supply all the devices required, a second 

distribution regulator and manifold will be 

needed. 

A distribution system that avoids these 

complications is one that contains a pressure 

regulator for each user. Such a device is 

illustrated in Figure 4-21. 

Manufacturers of airline respirators include 

instructions specifying the range of air pressures 

required to produce the flow rates to the device 

required by the NIOSH certification standards. 

For a tight-fitting facepiece in the continuousFigure 4-21. Recommended breathing-air distribution manifold configuration.

NUREG/CR-0041, Revision 1

Air Supply

Air Regulator 

® Pressure Gauge 

Female Quick Connect 

Air Hose Connection 

Filter 

Relief Valve 

63
flow mode, this is 4-15 scfm. For hoods, it is 

6-15 scfm. The air supply pressure required is 

based on the total length of supply hose used, 

and on the number of hose sections connected 

together. Each hose section incorporates a set of 

quick-connect fittings that cause a pressure 

drop. If a single device is used, and if the 

appropriate pressure is applied for the number 

of hose sections used, air flow to the user may 

be assumed to be within the required range. 

Licensees are never required to measure the 

flow rate of air supplied to a facepiece or hood. 

The licensee may assume that if the device is 

used in accordance with manufacturer's 

instructions (e.g., minimum and maximum hose 

lengths, proper air pressure at the point that the 

device is attached to the breathing-air source), 

then the air-flow rate will fall within the 

acceptable range. 

4.18.3 Air Supplied to High-Pressure 

Breathing-Air Cylinders 

In addition to the Grade D requirement, 

OSHA requires [29 CFR 1910.134(i)(4)(iii)] 

that the moisture content in breathing-air 

cylinders not exceed a dew point of-50 'F 

(-45.6 'C) at one atmosphere pressure. 

Compressed Gas Association (CGA) G-7.1

1997, "Commodity Specification for Air," 

states that air in SCBA cylinders should not 

exceed a dew point of-65 'F (24 ppm v/v), or 

10 'F lower than the coldest temperature 

expected in the area where the SCBA will be 

used. The NRC suggests compliance with the 

OSHIA requirement for all cylinders and 

suggests meeting the CGA Grade L 

requirement for moisture content, if practical.

4.18.4 Problems with Breathing-Air 

System Contamination 

Various problems have been encountered over 

the years regarding contamination of systems 

used to supply breathing air. In one incident,' 0 a 

combination service-air/breathing-air system 

was used to provide the motive force to 

backwash a demineralizer filter element. The air 

system became contaminated when water from 

the liquid radioactive waste system leaked past a 

check valve and an air-operated ball valve. 

In another instance,' radioactive gases from a 

reactor off-gas system leaked into the 

combination service-air/breathing-air system 

when the on-line and standby service air 

compressors failed and the system was 

depressurized. 

In a third instance,12 two workers became 

contaminated when they connected their 

respirators to an instrument air manifold. The 

initial surge of air contained dust and rust 

particles that were radioactive. The source of 

this contamination was not able to be 

determined. 

Licensees are advised to take the necessary 

precautions to prevent contamination of the 

breathing air system. Routinely opening system 

low-point drains, and allowing some air to flow 

out of an attachment point before connecting a 

distribution manifold may be considered to clear 

condensation or debris from the header. Care 

should be taken to not cause airborne 

contamination during these venting operations. 

Periodic radiological surveys of the breathing 

air and of critical system components should 

also be performed.

10 IE Information Notice No. 79-08 "Interconnection of 

Contaminated Systems with Service Air Systems Used 

as the Source of Breathing Air," March 28. 1979. 

" IE Information Notice No. 85-06 "'Contamination of 

Breathing Air Systems," January 23, 1985. "2 Ibid.

NUREG/CR-0041, Revision I 64
4.19 Emergency Entry and Escape 

Equipment (IDLH) 

4.19.1 Equipment for Emergency Entry 

Equipment approved for emergency entries 

into known or potential IDLH areas includes 

SCBA (pressure-demand and positive

pressure) and a combination supplied-air 

respirator with emergency escape air cylinder. 

4.19.2 Equipment for Emergency Escape 

One major consideration in choosing an 

escape respirator is the time required to don 

the device. Ideally, the escape device can be 

donned quickly during the time that the escape 

is being made. 

A positive-pressure, self-contained breathing 

apparatus (SCBA) provides the best available 

protection for a relatively long period of time, 

but donning time is relatively long. Even a 

well-trained, calm person cannot don an 

SCBA quickly. An emergency, with its 

attendant anxiety, may cause even longer 

donning times. Standard SCBAs should 

probably not be relied upon for escape 

purposes unless workers in the area are 

already wearing them when the emergency 

occurs. Even if it is being worn, a full-sized 

SCBA may impede escape from a rapidly 

developing emergency, so its respiratory 

protection capabilities must be balanced 

against a delayed escape. 

There are other types of atmosphere-supplying 

respirators specifically approved by NIOSH 

for escape. Most consist of a small 

compressed-air cylinder (3, 5, or 10 minutes) 

and a facepiece or hood. These can be quickly 

donned, but they are bulky, making them 

awkward to carry continuously. Another 

device consists of a nested coil of stainless 

steel tubing charged with breathing air to 

5,000 psi. This air supply feeds into a light 

plastic hood that fits over the wearer's head.

Figure 4-22. Self-contained 5-minute 

escape device.

This device will supply 5 minutes of breathing 

air. (See Figure 4-22.) 

If each worker cannot carry an escape device, 

relatively large numbers of these devices may 

need to be placed in accessible locations. A 

person in an area where an IDLH environment 

can occur should never be more than a few 

seconds away from an escape device. A 

combination airline respirator equipped with 

both an airline connection and a small tank of 

compressed air is useful for escape in case the 

main compressed-air supply fails. These are 

also classified as SCBAs by NIOSH. 

4.20 Potential Respirator Program 

Weaknesses 

Some potential weaknesses found in respirator 

programs, which apply primarily to power 

reactor licensees, but which might act as a 

reminder to other licensees, are listed below. 

(NRC Information Notices 98-20 and 99-05.) 

"* Requirements for members of the 

emergency response organization to be 

qualified to use respirators were eliminated; 

"* Key emergency response and operations 

personnel permitted to have facial hair, 

some of whom were committed to don 

SCBA within two minutes after initiation of 

an emergency;

NUREG/CR-0041, Revision I 65
"* Key emergency response and operations 

personnel unfamiliar with the locations of 

emergency response SCBAs; 

"* Key operations personnel had not had 

hands-on training with SCBA in five years; 

"* Air cylinder pressure in some SCBAs was 

below 90% of rated pressure (industry 

standard), and some were at less than 80% 

of capacity; 

"* Failure to realize that certain areas of the 

plant might become IDLH areas under 

certain postulated (design-basis) conditions; 

"* Failure of certain key emergency response, 

staff, security and operations personnel to 

maintain their respirator qualifications 

(annual fit testing and medical screening); 

"* Facepiece sizes for which certain 

emergency response and operations 

personnel had been fit tested were not 

available at all SCBA locations; and 

"* Reactor operators had not been trained on 

how to change SCBA cylinders. 

One other situation involved reactor operators 

who might be required to wear SCBA in the 

control room during an emergency. The back

mounted air cylinder made it impossible for 

operators to sit in any available control room 

chair. The need for chairs or stools without 

backs had not been anticipated. 

4.21 Decontamination and Sanitization of 

Facepieces; Contamination Control 

4.21.1 Introduction 

Proper cleaning, sanitization and 

decontamination of respiratory protection 

devices is essential to their safe use. Even 

apparently mild cleaning techniques can 

unwittingly cause a loss of safety function. 

Manufacturers' recommendations for cleaning 

and decontaminating a respirator are found in 

the technical literature supplied with the device. 

Additional information on the appropriateness 

of a particular cleaning technique can be

obtained by contacting the respective 

manufacturer. 

4.21.2 Elastomeric and Plastic Components 

Respirators may be cleaned by hand or using an 

automated system. Care must be taken to use a 

cleaner and a sanitizing agent that will not have 

a deleterious effect on the rubber or plastic 

components of the device. Respirator 

manufacturers usually only provide instructions 

for hand-washing respirators. Licensees should 

apply the same principles if they choose to 

automate the process. 

Instructions for cleaning respirators provided by 

some manufacturers indicate that the facepiece 

should be disassembled to some extent before 

being washed. This may be required after 

facepieces have been used in very dirty 

environments or when the nature of the 

contaminant dictates (e.g., biohazardous 

material). Based on long experience, NRC 

believes that most half-facepiece and full

facepiece respirators used in a radiological 

environment are lightly or moderately 

contaminated and are not really "dirty" in the 

traditional sense. These can be effectively 

decontaminated and sanitized without 

disassembly. Therefore full or partial 

disassembly is not necessarily required prior to 

decontamination or sanitization as long as the 

residual contamination guidelines are met and 

the sanitization is satisfactory. Heavily 

contaminated and physically dirty devices might 

require disassembly prior to cleaning. Another 

obvious exception would be for those facepieces 

equipped with electronic components that are 

part of a voice amplification system. It is the 

responsibility of the RPA to decide the best way 

to decontaminate and sanitize respirators and 

components. 

Manufacturers' recommendations must be 

heeded with regard to maximum water 

temperatures used when cleaning or sanitizing 

the respirators. The upper temperature limit is 

usually 43 'C (110 'F), but this may be different

NUREG/CR-0041, Revision 1 66
for some manufacturers. These temperature 

restrictions would also apply if heated air is 

used to dry the facepieces. 

Most manufacturers specify their own brand of 

cleaning and/or sanitizing solution. Other 

alternatives are acceptable. A hypochlorite 

solution (50 ppm chlorine in water), an aqueous 

solution of iodine (50 ppm iodine in water), or 

commercially available cleaners of equivalent 

disinfectant quality are acceptable when used as 

directed, and if their use is not prohibited by the 

respirator manufacturer. Instructions for 

sanitizing respirators often state that the 

facepiece should be "immersed" in the 

sanitizing solution for a specified period of time. 

In a program that uses a modified automatic 

dishwasher to clean and sanitize facepieces, the 

spray of disinfectant solution inside the machine 

effectively immerses the facepieces and is 

appropriate for sanitizing them. Alcohol

impregnated towelettes or wipes should not be 

used on elastomeric facepieces. A description of 

an improper respirator cleaning process that 

resulted in the rapid deterioration of certain 

parts of the respirator is the subject of IE 

Information Notice No. 86-46. 

Respirators being taken out of storage and being 

returned to service should be inspected and 

resanitized prior to issue. In this case, a survey 

for residual contamination would not be 

required if the facepieces had met the 

radiological criteria prior to being put into 

storage. 

4.21.3 SCBA Cylinders 

NIOSH recommends' 3 special attention and 

increased oversight and inspections for certain 

high-pressure aluminum seamless and 

aluminum composite hoop-wrapped cylinders 

made of aluminum alloy 635 1-T6 by Luxfer. 

These cylinders may develop cracks in the 

neck and shoulder area, leading to greater

"• NIOSH Respirator User Notice, December 7, 1999 

<http://www.cdc.gov/niosh/3al run.html>.

than-normal loss of air during storage, and 

ruptures that may lead to serious injury or 

death. Additionally, short of catastrophic 

failures, the unexpected loss of air (and 

reduction of service time) could lead to 

reduced worker safety and less effective 

emergency response. Luxfer cylinders 

manufactured in the United States after 1988 

use a different alloy and are not subject to the 

NIOSH notice. The affected cylinders are used 

on various NIOSH-approved SCBA, including 

various sizes and rated durations ranging from 

5 to 30 minutes.14 Licensees should review 

this information for applicability to their 

facilities and consider actions, if appropriate, 

to upgrade their self-contained breathing 

apparatus (SCBA) cylinder inspection 

program. 

Stripping the paint from SCBA air cylinders to 

remove fixed contamination is not usually an 

acceptable practice. An important safety 

function will be lost if the cylinders are 

not repainted with the proper paint because the 

manufacturer-applied coating is designed to 

discolor at 350 'F to indicate that the cylinder 

has been exposed to excessive heat. Also, 

significant degradation of structural integrity 

can result if this decontamination technique is 

used on composite air cylinders. Commercial 

paint stripper will attack the bonding material of 

the reinforcing fiberglass wrapping.15 

4.21.4 Radiological Guidelines for Reuse 

Dust masks (i.e., those that do not meet the 

definition of a half-facepiece) should be 

disposed of after each use. For subsequent 

"14 See also NRC Information Notices 83-68, 84-34, 85

48, 86-24 and 2000-07 

<http://www.nrc.gov/NRC/reference.html>. 

'5 NIOSH Respirator Users Notice, July 30, 1996. 

"Safety Advisory on The Potential for Sudden Failures 

of Fiberglass-wrapped Composite Aluminum Cylinders 

Following Exposure to Acidic Chemical Cleaning 

Agents." <http://www.cdc.gov/niosh/cylinder.html>

NUREG/CR-0041, Revision 1

t !

67
exposures workers should obtain a new dust 

mask. 

All other respirators may be reused by the 

same person on the same working day as long 

as the licensee has reasonable assurance that 

the interior portions of the device do not 

contain significant contamination. One of 

more of the following methods could be 

employed to achieve such assurance: 

"* Store device in a clean plastic bag 

between uses; 

"* Store device in an uncontaminated area; 

"* Wipe out device interior with a clean, 

damp cloth before reuse; and 

"* Survey device interior before reuse. 

Establishing acceptance criteria for reuse of 

devices as described above are left to the 

discretion of the licensee. 

4.21.5 Radiological Guidelines for Reissue 

Suggestions for limits on residual 

contamination inside the facepiece and on the 

face-seal area are provided in Table 4-22 

below. Fixed contamination levels on the 

outside of the facepiece could be higher. 

Table 4-22. Recommended contamination 

guidelines for facepiece interiors prior to 

reissue. 

U 3 or 3y 

(dpm per (dpm per 

100 cm 2) 100 cm 2) 

Total 

contaminationa <100 <5000 

(direct survey) 

Removable 

contamination <20 <1000 

(wipe survey) 

spots of contamination may be averaged over SSmall 

100 cm2 for comparison to the guideline values. Hot 

particles should be removed.

These same guidelines can be used for 

interiors of air hoses, breathing tubes, 

regulators, quick connect fittings and the like. 

Interiors of these components should be 

surveyed periodically, for example, once or 

twice per year or when contamination is 

suspected. 

Allowable radiological guidelines for the reuse 

of other equipment in restricted areas (e.g., 

exterior of air hose, exterior of regulators, 

exterior of breathing tubes, exterior of SCBA 

cylinders, etc.) may be substantially higher 

than those suggested for facepiece interiors. 

While most loose contamination should be 

removed from these components before 

storage or reuse, total contamination 

guidelines can be established based either on 

total activity or on dose rate, and should be 

ALARA. If respiratory protection equipment 

containing fixed contamination is stored in 

areas other than restricted areas, ensure that 

the requirements of 10 CFR 20 are met with 

regard to posting and labeling. Equipment that 

is stored outside a restricted area16 should have 

no detectable contamination. 

At facilities where alpha contamination is 

possible but unlikely, surveying every 10th or 

151h facepiece for alpha contamination is 

sufficient. Where both alpha and beta 

contamination are known to be present, each 

facepiece should be tested for both categories 

of contaminants, although a validated beta

gamma to alpha ratio may be used. At 

facilities that are licensed only for possession 

of beta- and/or beta-gamma-emitting isotopes, 

or for sealed alpha-emitting sources, or if a 

facility does not use alpha-emitting 

radionuclides, no alpha survey is required. 

16 Restricted area is defined in 10 CFR 20.1003 as an 

area, access to which is limited by the licensee for the 

purpose of protecting individuals against undue risks 

from exposure to radiation and radioactive materials. 

Most nuclear reactor sites use the term radiologically 

controlled area (RCA) instead.

NUREG/CR-0041, Revision I 68
If a licensee uses a direct measurement with a Equipment-to-detector survey distance should 

gamma-sensitive or beta-sensitive monitor to be the same as that used to establish the 

screen respirators for contamination prior to counting efficiency. 

reissue, the MDA for the counter should be 

low enough to detect the activities specified The guidelines suggested in this section 

with 95% confidence. If the sensitivity of the should not be interpreted as being criteria for 

direct survey method is good enough to show the release of respirators or other equipment to 

compliance with the removable contamination unrestricted areas or for unrestricted use. 

guideline, no wipe survey need be performed. 

Where alpha contamination is involved, a 

beta-to-alpha ratio may be used so long as the 

ratio is satisfactorily established. 

References and Resources 

I. American National Standards Institute/Compressed Gas Association. "American National Standard 

Method for Marking Portable Compressed Gas Containers to Identify the Material Contained." 

ANSI/CGA C-4-1990, May 29, 1990. 

2. Compressed Gas Association. "Standards for Visual Inspection of Steel Compressed Gas Cylinders." 

CGA C-6-1993. 

3. Compressed Gas Association. "Commodity Specification for Air." CGA G-7.1-1997. 

4. Compressed Gas Association. "Safe Handling of Compressed Gases in Containers." CGA P-I

1991. 

5. Compressed Gas Association. "Compressed Air for Human Respiration." CGA G-7-1990. 

6. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, 

National Institute for Occupational Safety and Health. "NIOSH Guide to the Selection and Use of 

Particulate Respirators Certified Under 42 CFR 84." Publication No. 96-101, 1996. Education and 

Information Division, Cincinnati, OH, January 1996. 

7. Bollinger, Nancy L. and Robert H. Schutz. "NIOSH Guide to Industrial Respiratory Protection." 

U.S. Department of Health and Human Services, DHHS (NIOSH) Publication No. 87-116, 1987. 

8. NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84. 

January 1996. 

9. NIOSH: Service Time Recommendations for P-Series Particulate Respirators. NIOSH Page 1, 

(1997, May 2). 

10. Yoon, Y.H., J.H. Nelson and Jaime Lara: Respirator Cartridge Service-Life: Exposure to 

Mixtures. Am. Ind. Hyg. Assoc. J. 57: 809-819, (1996). 

11. "NIOSH Respirator Decision Logic." U.S. Department of Health and Human Services, DHHS 

(NIOSH) Publication No. 87-108, 1987. 

12. "NIOSH Certified Equipment List," as of September 30, 1993. U.S. Department of Health and 

Human Services, DHHS (NIOSH) Publication No. 94-104, 1993. 

a. (NIOSH publications are available from Publications Dissemination, 4676 Columbia 

Parkway, Cincinnati, OH 45226-1998. Phone (800) 35-NIOSH, Fax: (513) 533-8573; 

website: http://www.cdc.gov/niosh/homepage/html.) 

13. C. A. Burchsted, A. B. Fuller, and J. E. Kahn, Nuclear Air Cleaning Handbook, U.S. Government 

Printing Office, Washington, DC, ERDA 76-21 (1979), chs. 1-3. 

14. Quality Assurance Testing of HEPA Filters and Respirator Canisters, U.S. Department of Energy, 

Washington, DC, NE F 3-43 (June 1984).

69 NUREG/CR-0041, Revision 1
15. Specifications for HEPA Filters Used by DOE Contractors, U.S. Department of Energy, 

Washington, DC, NE F 3-45T (1984). 

16. Operating Policy of DOE Filter Test Program, U.S. Department of Energy, Washington, DC, NE 

F 3-42 (1984). 

17. National Fire Protection Association, "Open Circuit Self-Contained Breathing Apparatus for Fire 

Fighters," ANSI/NFPA 1981, 1997 edition. 

18. Letter, LeMoine J. Cunningham, Chief, Radiation Protection Branch, NRR to John F. Schmidt, 

Chief Health Physicist, Nuclear Management and Research Council, August 26, 1992. 

19. Health Physics Position-226 (HPPOS-226). The health physics position was written in the context 

of 10 CFR 20.103, but it also applies to "new" 10 CFR 20.1703. See also the letter from L. J. 

Cunningham to S. K. Herweyer (TSI Incorporated) dated February 27, 1990. 

20. NIOSH Respirator User Notice, May 2, 1997 <http://www.cdc.gov/niosh/respupdt.html>. 

21. NIOSH Respirator User Notice, May 2, 1997 <http://www.cdc.gov/niosh/respupdt.html>. 

22. NIOSH Respirator Users Notice, July 30, 1996. "Safety Advisory onl The Potential for Sudden 

Failures of Fiberglass-wrapped Composite Aluminum Cylinders Following Exposure to Acidic 

Chemical Cleaning Agents." <http://wwwv.cdc.gov/niosh/cylinder.html>. 

23. IE Information Notice No. 86-46. "Improper Cleaning and Decontamination of Respiratory 

Protection Equipment," June 12, 1986.

NUREG/CR-0041, Revision I 70
5 RESPIRATOR USERS

5.1 Medical Evaluation 

The purpose of the respiratory protection 

program is to protect the health of workers. 

One component of that program is the medical 

evaluation. The use of a respirator imposes 

particular physiological demands on the 

wearer. These demands could jeopardize the 

health or even the life of a user who has 

certain medical conditions. A medical 

evaluation is designed to identify these 

conditions so that they can be taken into 

account when deciding the proper respiratory 

protection for a worker without endangering 

his/her health or life. For some medical 

conditions the kinds of respirators that may be 

used might have to be limited. For more 

serious conditions such as those that might 

lead to the inability to breathe, cause a heart 

attack, vascular accident or seizure, the use of 

respirators might be precluded entirely. 

Medical screening is not required for 

individuals who will only wear filtering 

facepiece respirators or dust masks with no 

APF as described in Regulatory Guide 8.15, 

Section 4.8. Also, no medical screening is 

required for personnel who are not respirator 

wearers but who might infrequently need to use 

an emergency escape respirator. 

5.1.1 The Licensee's Physician 

The physician selected by the licensee should 

be made aware of the types of respiratory 

protection devices used by the licensee, and 

should have an opportunity to experience the 

stresses associated with wearing and using 

SIE Information Notice No. 84-24: "Physical Qualification 

of Individuals to Use Respiratory Protective Devices," 

dated April 5, 1984, describes a fatality involving a worker 

who had been wearing a respirator, and provides guidance 

on medical screening programs for respirator users.

these devices. (S)he should also be aware of 

the range of potential environmental 

conditions in which the respiratory devices 

might be worn (e.g., high temperature, high 

humidity), and the types of protective clothing 

that might typically be worn in conjunction 

with the respirators. In short, the licensee's 

physician should have an adequate knowledge 

of all the stresses respirator wearers might be 

subjected to in the workplace in order to make 

informed judgments about who should and 

should not be permitted to use respirators. 

This knowledge will also allow informed 

decisions to be made regarding individuals 

who might be permitted to use certain types of 

respirators but not others, who may wear 

respirators but perform only supervisory or 

light work, and who should not use any type 

of respirator. 

The licensee's physician should determine 

which screening methods and tests are 

appropriate, should set the acceptance criteria 

for those methods and tests, and should 

periodically review the implementation of the 

program. The screening process should be 

sufficient (in the opinion of the licensee's 

physician) to identify any person who should 

not use respiratory devices for medical 

reasons, or who should be limited to the use of 

specific types of devices. The NRC 

regulations do not require a "hands-on" 

physical examination by a physician. 

The licensee should choose a physician with 

an appropriate specialty (e.g., internal 

medicine, industrial medicine, family 

practice), and the licensee's physician should 

be licensed to practice medicine in the United 

States. 

The physician should review the program 

implementation periodically during visits to 

the licensee's facility.

71 NUREG/CR-0041, Revision I
5.1.2 Establishing and Performing 

the Evaluation 

The licensee's physician should identify those 

physiological factors that are to be measured 

or asked about during the screening process. 

The screening should include a medical 

history questionnaire. The questionnaire 

should be designed to elicit information from 

the person being screened regarding critical 

conditions or diseases. The OSHA Respirator 

Medical Evaluation Questionnaire contained 

in Appendix C to 29 CFR 1910.134 is 

acceptable to NRC, and is Appendix C to this 

Manual. The physician may also use the 

results of measurements (e.g., spirometry 

testing, blood pressure, temperature, pulse) to 

supplement the questionnaire. Finally, ANSI 

Z88.6-1984, "Respirator Use-Physical 

Qualifications for Personnel,"2 provides 

guidance that is acceptable to the NRC staff 

for the physician to use in determining 

medical fitness. Overall responsibility for the 

medical screening program always rests with 

the licensee's physician, who establishes the 

precise screening method. 

The medical evaluation program should be 

carried out by the physician, or by a certified, 

medically trained individual such as a 

registered nurse (RN), licensed practical nurse 

(LPN), emergency medical technician (EMT), 

or someone who, in the judgment of the 

licensee's physician, has adequate experience, 

education, training, and judgment to 

administer the screening program. 

Appointment or approval of the medical 

screening program staff should be in writing 

from the licensee's physician. 

The physician establishes, in writing, which 

answers to the medical history questions, and 

which measured parameters are acceptable and 

which are not. (S)he should be available by 

phone to resolve any implementation issues 

2 This standard has been withdrawn by ANSI in 

anticipation of the issuance of an updated version, which 

will contain expanded guidance.

with the individual(s) who are administering 

the program at the licensee's facility, and 

should periodically review (on-site) the 

implementation of the program. The physician 

need not review or sign the records of each 

person who is screened and who meets the 

acceptance criteria. However, approval to use 

one or more types of respirator for an 

individual who fails to meet the minimum 

medical screening criteria should be signed by 

the licensee's physician. 

Those individuals who fall outside the bounds 

of the established acceptance criteria may be 

examined by the determining physician, who 

can then make a medical judgement about 

which type(s) of respirator(s) the individual 

may or may not wear. Notification may be 

given to the Respirator Program Administrator 

(RPA) in the form of a Respirator User 

Medical Status form (see Appendix D to this 

document). 

5.1.3 Psychological Factors 

It is generally very difficult to evaluate a 

wearer's psychological limitations by means 

of a routine medical examination. The 

licensee's physician should investigate any 

identified psychological conditions thoroughly 

to ascertain that the wearing of respiratory 

protection equipment will not aggravate an 

existing condition. Even under ideal 

conditions, a degree of anxiety is often 

encountered by respirator wearers, and this 

anxiety may become exaggerated during an 

emergency. 

Most individuals, especially inexperienced 

respirator users, experience some level of 

psychological stress when using a respirator. 

Also, the normal increase in depth and 

frequency of respiration due to the additional 

dead-air volume resulting from the facepiece 

is often interpreted as a sign of anxiety. The 

licensee should obtain reasonable assurance 

that respirator users will not experience

NUREG/CR-0041, Revision I 72
unmanageable respirator-induced 

psychological stress to the extent that they run 

the risk of injuring themselves or their co

workers when respirators are worn. Questions 

regarding claustrophobia, extreme anxiety, 

respirator-related anxiety problems previously 

experienced, and other related conditions are 

therefore appropriate on the medical screening 

questionnaire. 

Potential respirator wearers who are observed 

during training, especially the hands-on 

portion, to be overly anxious or agitated while 

wearing a respirator should be referred to the 

medical screening staff or to the determining 

physician for further evaluation. Likewise, 

those who exhibit similar behaviors during fit 

testing should be referred to the medical 

group. 

This represents the actions expected of the 

licensee to screen out individuals who might 

experience psychological stress brought on by 

respirator use. The NRC recognizes that some 

individuals might be unwilling to answer 

medical screening questions candidly, which 

may lead to misinformation being provided on 

medical screening questionnaires. 

5.1.4 Timing of Medical Evaluations 

According to 10 CFR 20.1703(c)(5), the initial 

medical evaluation to determine a worker's 

fitness to use respirators must be 

accomplished prior to respirator fit-testing for 

tight-fitting facepieces and prior to the first 

field use for loose-fitting devices, since no fit

test is required for these types. 

NRC regulations require that a worker must be 

re-evaluated medically every 12 months 

thereafter or at some other frequency 

established by the licensee's physician. ANSI 

Z88.6-1984 suggests a range for reevaluation 

from every 5 years for workers below age 35, 

to annually for workers over age 45. ANSI 

Z88.2-1992 concurs. Licensees are reminded

that OSHA requirements specify annual 

medical screening with no allowance for 

longer periods under any circumstances. 

If necessary, a re-evaluation "grace period" of 

up to 90 days is considered to be reasonable.3 

In unusual circumstances, an otherwise fully 

qualified respirator user whose medical 

screening has expired within the past 90 days 

may be issued a respirator with the 

concurrence of the RPA. Licensees should not 

interpret this grace period to mean that re

screening can be accomplished every 15 

months. For example, Health Physics Position 

219 referred to above specifies that, if annual 

re-screening is indicated, three consecutive 

examinations should not exceed 39 months. 

5.1.5 Failure To Meet the 

Acceptance Criteria 

If an individual's screening results fall outside 

the range of the acceptance criteria, the 

licensee may choose to have the case referred 

to the licensee's physician for further 

evaluation. This evaluation might consist of a 

telephone conference with the individual being 

screened or with the on-site medical 

representative, a review of the written records, 

or possibly a hands-on examination. In this 

case the physician has three options: 

"* Permit unconditional use of respirators; 

"* Confirm the outcome of the screening and 

prohibit any use of respirators; or 

"* Permit use of one or more respirator types 

and prohibit the use of others. 

Presumably, if conditional approval is granted 

to use only some types of respirators, these 

will be ones that involve less worker stress 

(e.g., supplied-air hoods or powered air

purifying respirators). 

' G.D. Kerr et al., "Health Physics Positions Data Base," 

Health Physics Position 219, NUREG/CR-5569, 

Revision 1, page 120. February 1994.

NUREG/CR-0041, Revision I 73
Alternatively, the physician might specify that 

respirators may be used by such an individual 

provided that only supervisory activities 

(rather than physical labor) be performed. 

5.1.6 Approval by Other Physicians 

Medical evaluations performed by a physician 

other than the licensee's physician may be 

acceptable as long as comparable screening 

tests and acceptance criteria are used for 

screening individuals. The licensee's 

physician should review the screening 

methods used by the other organization and 

approve or disapprove it in writing. This is 

also true of licensees who utilize a centralized 

records data base. If the respirator medical 

screening programs of all the participants in 

the data-sharing network have been cross

reviewed and approved, use of such data is 

acceptable in lieu of the licensee re-screening 

the individuals involved. 

5.1.7 Privacy of Medical Records 

Medical records and the results of medical 

screening tests should be kept confidential. 

The only information that should be 

transmitted from the medical department to 

the RPA is whether or not an individual may 

use respirators, or which devices may be used 

and which may not be. A simple medical 

status form is adequate (see Appendix D). 

5.1.8 Medical Status Forms 

Upon completion of each respirator medical 

screening, a "Respirator User Medical Status" 

form should be filled out. This form should 

contain enough information to clearly identify 

the screened person. It should then indicate 

one of three statuses: 

1. Approved for use of all types of 

respirators; 

2. Not approved for use of any respirator; or

3. Conditional approval. Approved for use of 

some types of respirators but not for 

others. The types allowed or prohibited 

should be specified. 

An example of a form that may be used is 

provided in Appendix D to this Manual. 

If the first or second option is indicated, the 

form need only be signed by the person 

performing the screening. 

If the third option is indicated, the physician's 

specific instructions should be noted, and the 

form signed by the licensee's physician. Faxed 

copies are acceptable. A copy of the 

Respirator User Medical Status form should 

be sent to the RPA, and another should be 

given to the subject. The original should be 

retained in the subject's medical record. 

5.2 Training 

5.2.1 Qualifications of Training Personnel 

Individuals performing respirator user training 

should have expertise in radiation protection 

and should themselves be experienced in using 

all the types of respirators that are the subject 

of the training. Ideally, they should also be 

trained in presentation skills, and have 

experience instructing classes or making oral 

public presentations. 

5.2.2 Contents of Training Program 

A training program, including hands-on 

training, should be established and 

implemented for respirator users. Initial 

training for inexperienced respirator users and 

for first-time respirator users should take place 

before fit testing. Hands-on training may not 

need to be repeated annually for workers who 

use respirators frequently, but retraining 

sessions should review and at lease 

demonstrate proper donning, performance of 

user seal checks, and removal procedures.

NUREG/CR-0041, Revision 1 74
Retraining of workers who have not used 

respirators during the past year, or those who 

have used them infrequently, should include 

hands-on training. 

Respirator inspection, donning, user seal 

checking, use and proper removal are 

mechanical skills. As such, they require a first

time trainee to actually perform these actions a 

number of times while being observed (and 

corrected as necessary) by an experienced 

respirator user/instructor in order to achieve an 

acceptable level of proficiency. This practice

under-instruction provides a high degree of 

confidence that when the worker dons a 

respirator in the field, it will likely be donned 

properly and will afford the predicted 

minimum degree of protection. Performing an 

action several or many times reinforces 

learning. The more correct repetitions of a 

task, the longer the trainee will maintain 

proficiency at performing that task 

unsupervised. As an analogy, consider a novice 

welder in training. If the novice were to observe 

an instructor performing and explaining even a 

simple weld, we would not expect the trainee to 

be able to perform such a weld correctly the first 

time without any practice. Simply presenting a 

demonstration of the respirator skills described 

above is not adequate training. 

Topics addressed during respirator training 

should include the following for each device 

the trainees will use in the field and for 

emergency escape respirators: 

I. Principles of operation; 

2. Capabilities and limitations; 

3. NIOSH approval requirement; 

4. How to communicate clearly with fellow 

workers while using respirators; 

5. Proper use of equipment associated with 

each device (e.g., voice amplification 

units, spectacle adapters); 

6. Potential respirator-related problems, such 

as lens fogging in a full-facepiece 

respirator; 

7. How to inspect each type of respiratory 

protective device to be used, and be

instructed to perform this inspection prior 

to donning a device; 

8. For face-sealing devices, be instructed in 

how to perform a user seal check, and be 

instructed to perform this fit check each 

time this type of device is donned; 

9. For non-face sealing device, be instructed 

in how to perform an operational check, 

and be instructed to perform this 

operational check each time this type of 

device is donned; 

10. Be informed that each respirator user may 

leave the work area at any time for relief 

from respirator use in the event of 

equipment malfunction, physical or 

psychological distress, procedural or 

communications failure, significant 

deterioration of operating conditions, or 

any other conditions that might necessitate 

such relief. 

11. Training should also include information 

about the types of physical or medical 

conditions that might indicate respirators 

should not be used, a description of 

respirator cleaning and sanitization 

program, a description of the inspection 

and maintenance programs, and the 

respirator issue procedure; and 

12. Be advised that a new fit test should be 

requested if any of the changes listed in 

section 5.7 of this Manual apply to the 

respirator wearer. 

5.2.3 Effective Respirator Training 

In the classroom portion of the program, each 

trainee should be given a respirator of the type 

that is the subject of the training. As the 

instructor describes the component parts and 

principles of operation, trainees are able to 

clearly identify each part while seeing how it 

operates. Trainees are also shown how the 

straps are tightened and loosened, check 

exhalation valve operation and so on. The 

instructor emphasizes that respirator users 

must always perform this visual inspection 

prior to donning.

NUREG/CR-0041, Revision 1 75
Next, the instructor demonstrates the respirator 

donning, negative- and/or positive-pressure user 

seal check (see Figure 5-1), and removal 

procedure while the trainees watch. The 

demonstration should be repeated. Finally, the 

trainees don their own respirators while the 

instructor recites the donning instructions aloud. 

The instructor closely observes the trainees and 

corrects any mistakes. The instructor then 

recites the instructions for the negative- and/or 

positive-pressure user seal checks as the trainees 

perform the operations. Strong emphasis should 

be placed on how to correctly conduct one or 

more user seal checks. Trainees must learn to 

recognize the symptoms of a respirator 

malfunction that the checks are designed to 

detect, and must learn what action they should 

take if a facepiece fails a user seal check. The 

respirators are then removed in accordance with 

the instructor's verbal directions. Again, the 

instructor corrects any mistakes made by the 

trainees and provides positive reinforcement 

when they perform the tasks correctly. This 

positive reinforcement is important, since it 

must be clear to each trainee that he or she is in 

fact performing the task correctly. The 

instructor also solicits questions from the class 

to see if there were any problems or 

misunderstanding of instructions. 

Finally, the trainees are told to don their 

respirators in the way that they have just 

practiced. The instructor observes them closely 

and corrects as necessary. Negative and/or 

positive-pressure user seal checks are then 

performed. During this hands-on training, with 

respirators on, each trainee should perform a 

series of activities such as operating a valve, 

reading a gauge or performing similar tasks that 

might be required in the workplace. This is also 

a good opportunity to let the trainees practice 

verbal communications with one another to get 

used to coping with the voice distortion imposed 

by the facepieces. After some period of 

respirator use, the trainees should remove the 

respirators as the instructor watches. Positive 

reinforcement should again be given for correct 

performance. Trainees should then don and

Figure 5-1. Positive-pressure (top) and 

negative-pressure (bottom) user seal checks. 

remove the respirators correctly (without 

prompting) at least two more times while the 

instructor observes. 

One thing to avoid, especially during initial 

respirator training, is a demonstration of how 

not to don or remove a respirator. While an 

instructor can make this very amusing, studies 

have shown that this negative training will be 

remembered as well as or better than the correct 

training. This would obviously be 

counterproductive.

NUREG/CR-0041, Revision I 76
Once effective training is complete, the trainee 

should be able to correctly don and use the 

respirator during the fit test. 

5.2.4 Training for Supervisors of 

Respirator Users 

In addition to respirator users, supervisors of 

respirator users should also receive training, 

even if they are not themselves respirator users. 

A list of topics for supervisor training can be 

found in ANSI Z88.2-1992, paragraph 8.1.1. 

These supervisors should also receive the 

hands-on training. If such supervisors are 

excluded from respirator use on medical 

grounds, they should at least observe the hands

on training. Fit testing for supervisors is not 

required unless they will be respirator users. 

5.3 Fit Testing 

5.3.1 Introduction 

Fit testing is, and probably always will be, a 

laboratory situation where the adequacy of a 

respirator fit is determined under ideal 

conditions. The physical stresses placed on the 

facepiece-to-face seal in the workplace are 

extremely variable in type and intensity. 

A fit-testing program is to be implemented for 

all face-sealing respirators, even those that 

will be used only in a positive-pressure mode 

in the field. Each time fit testing is required, 

only a single satisfactory fit test need be 

performed for each facepiece. Separate fit tests 

are required for each manufacturer's model, 

size and facepiece material that the individual 

might use. For example, if a specific make, 

model and size facepiece is supplied in both 

carbon rubber and silicon rubber versions, and 

the user might be issued a facepiece made of 

either material, a separate fit test should be 

performed for the carbon rubber and silicon 

rubber facepieces.

Fit testing should always be performed with 

the facepiece operating in the negative

pressure mode, regardless of the mode of 

operation in which it will be used in the field. 

An adequate fit with a tight-fitting positive

pressure facepiece is important to prevent the 

possible ingress of contaminants, especially at 

high work rates. It is also important to ensure 

that the service-life of a SCBA is not reduced 

by the escape of compressed air past an 

inadequate face-to-facepiece seal. 

In a properly administered fit-test program, 

adequate fit factors should be obtained for 

more than 99% of test subjects who are free of 

facial deformities that preclude an adequate 

respirator fit. For those individuals who are 

unable to achieve a fit factor 10 times the APF 

of the respirator, consideration should be given 

to a positive pressure face sealing device or to 

a device for which a face seal is not necessary. 

A new ANSI standard, Z88.10-200x, 

"Respirator Fit Test Methods," is in the final 

stages of review and should be published 

soon. Licensees should review this document 

after its publication for ways to improve their 

fit-testing program. 

5.3.2 Relationship Between Fit Testing 

and Training 

A few respiratory protection training programs 

have been observed in which respirator fit 

testing is utilized as a substitute for the "hands

on" portion of initial respirator user training 

(i.e., the training of those who have little or no 

experience in the use of respirators). 

Theoretically, where this situation prevails, 

inexperienced workers can satisfactorily 

complete initial radiation worker/respirator user 

training without ever having touched a 

respirator, or at least never having donned one 

under instruction. 

Fit testing is not a substitute for hands-on 

training. Each person to be fit tested should be 

competent to properly don a facepiece and

NUREG/CR-0041, Revision I 77
perform at least one appropriate user seal 

check. No person, including the fit-test 

technician, should coach the subject during the 

respirator donning process, since no coach will 

be available in the workplace. If a person 

presents himself for a fit test and is unable to 

don a facepiece properly, no fit test should be 

administered, since the person has not been 

adequately trained. The fit test, then, is also a 

test of training effectiveness. The fit-test 

technician should observe the donning and user 

seal checking process to ensure that the device 

has been donned correctly. If it has not been, the 

fit test should not proceed. The individual 

should be referred to the appropriate person for 

retraining or for a refresher. 

At a facility where budgets and staff may be 

shrinking, the RPA might be tempted to cut 

costs by presuming that the respirator fit test 

could be substituted for the hands-on portion of 

the training program. This would shorten the 

initial worker-training program, eliminate 

purchase and maintenance of respirators for use 

in training, and eliminate the need to sanitize the 

training respirators after each class. Without 

hands-on training, however, no effective 

training takes place, and much of the time spent 

in class talking about respirator use is wasted. 

The purpose of a fit test is to gain assurance that 

a trained and practiced worker who dons a 

respirator unassisted, as he or she would in the 

workplace, will obtain an acceptable respirator 

fit. 

5.4 Quantitative Fit Testing (QNFT) 

In a quantitative fit test, the test subject is 

exposed to a challenge aerosol while wearing 

a respirator and a sample of the air inside the 

facepiece is analyzed for the challenge 

aerosol. The concentration inside the facepiece 

is compared to the challenge concentration 

outside the facepiece, and a numerical "fit 

factor" is obtained. QNFT, then, provides a 

numerical value that is indicative of how well 

or how poorly a respirator fits a test subject. It

is an objective test that is very much under the 

control of the person conducting the test, and 

not the fit-test subject. 

Historically, the challenge agent has been a 

mechanically generated aerosol mist of corn 

oil, dioctyl sebacate (DOS), or similar 

substance injected into a fit test chamber 

where the test subject is positioned. [Dioctyl 

pthalate (DOP) should not be used for QNFT 

since it is a suspected carcinogen.] The 

challenge concentration is maintained constant 

over the duration of the test. A newer test 

technology (PortacountTM ) uses ambient dust 

particles in the air as its challenge agent, thus 

eliminating the need for a test chamber and 

aerosol generator. 

A QNFT program is more expensive to run 

than a qualitative fit test program (QLFT), 

because of the equipment that must be 

purchased and maintained. Additional training 

is also required for the operator of the fit-test 

equipment, and for those who interpret the test 

results. 

In order for a licensee to use an APF >10 for 

any face-sealing respirator, QNFT is required 

and an adequate fit factor measured. Currently 

available QLFT methods are only capable of 

measuring a fit factor of 100. The requirement is 

that a fit test must measure a fit factor that is 10 

times the APF of the tested respirator, or a fit 

factor of 500 for facepieces that will be used 

with positive-pressure devices. 

Some respirators used for QNFT may need to 

be modified to perform the tests. While this 

modification voids the NIOSH approval for 

the device, no such approval is required for 

respirators used during fit testing, since 

occupational exposures to hazardous or 

radioactive materials are not involved. Some 

respirator manufacturers provide adapters that 

enable QNFT to be performed without 

permanently altering the facepiece.

NUREG/CR-0041, Revision 1 78
A few licensees who have obtained the NRC's 

authorization to use an APF for combination 

particulate and organic vapor chin-mounted 

canisters, have reported some radioiodine 

uptakes in wearers of this device. It has been 

postulated that the reason for this might be the 

stress that such a canister places on the 

facepiece seal when the wearer moves about in 

the work place. Consideration should be given 

to using these "iodine canisters" during QNFT 

of individuals to determine whether the added 

weight of the canister has any effect on the 

quality of the fit. See Figure 4-19. 

5.5 Qualitative Fit Testing (QLFT) 

In a qualitative respirator fit test (QLFT), the 

test subject, while wearing an unmodified 

respirator with the proper cartridge(s) 

attached, is exposed to a challenge aerosol or 

vapor. If the challenge agent is not detected 

(i.e., smelled or tasted) by the test subject, the 

respirator is judged to fit adequately. 

Negative- and positive-pressure user seal 

checks are not qualitative fit tests. 

There are some obvious drawbacks to this type 

of test. First, the test subject may report 

inaccurately. This may be caused by a 

misunderstanding of the test instructions or by 

a realization that a failed test might mean 

termination of employment. Second, 

depending on which challenge agent is 

utilized, some people may not be able to smell 

or taste it in the low challenge concentrations. 

One, isoamyl acetate (banana oil), will de

sensitize the olfactory nerves of a test subject 

if that subject is exposed to the vapors before 

the test is conducted. Another accepted 

challenge aerosol is sodium saccharine. Only 

one recognized challenge agent evokes an 

involuntary response from a test subject, and 

that is irritant smoke (stannic oxychloride). 

A QLFT program is less expensive to establish 

and run than a QNFT program, since very 

little equipment needs to be purchased and 

maintained.

A common misunderstanding about QLFT is 

that it takes less time to perform than a 

quantitative test. This is not the case. The 

exercise portion of the fit test protocol (i.e., 

which exercises are to be performed, how they 

are to be performed, and for how long) should 

be the same, no matter which test method is 

used. 

5.5.1 Capabilities and Limitations of QLFT 

Currently available QLFT methods are only 

considered capable of verifying a fit factor of 

100. Therefore QLFT methods can only be used 

for facepieces for which an APF •<10 will be 

used. For example, if a full facepiece air

purifying respirator is tested using QLFT, it 

may still be used in the field so long as an APF 

no greater than 10 is used. Since respirators that 

operate in a positive-pressure mode require a 

minimum fit factor of 500 before the APF listed 

in Appendix A to 10 CFR 20 can be applied, an 

APF of no more than 10 can be used for these 

devices in a program that utilizes QLFT 

exclusively. 

5.5.2 Irritant Smoke 

These tubes contain stannic chloride (SnCl 4), 

which reacts with ambient humidity to liberate 

a white hydrochloric acid fume and tin 

compounds. This smoke is a strong irritant of 

the eyes, mucous membranes, and skin, and 

evokes an involuntary response from the 

person who inhales it. For this reason it is the 

least subjective QLFT method. 

The National Institute for Occupational Safety 

and Health (NIOSH) conducted a Health 

Hazard Evaluation (HHE) in response to a 

request after four fire fighters reported 

experiencing either skin irritation or eye 

irritation as a result of qualitative fit tests using 

irritant smoke. The health risks associated with 

the use of irritant smoke were evaluated by 

conducting particle size analysis of the "smoke"

79 NUREG/CR-0041, Revision 1
emitted from air flow indicator tubes, and by 

measuring the concentration of hydrogen 

chloride produced by these tubes. Count median 

diameters of the smoke ranged from 0.33 to 

0.63 tim. Concentrations of hydrogen chloride 

measured on a day with low relative humidity 

ranged from <1 ppm to 2,700 ppm. 

Concentrations of hydrogen chloride measured 

on a day with high relative humidity ranged 

from 100 ppm to 11,900 ppm. The highest 

concentration measured inside the test hood 

during multiple bulb squeezes was 14,400 ppm. 

Inhalation of hydrogen chloride at 

concentrations of 5 ppm or more is immediately 

irritating to the nose and throat. In addition to 

upper respiratory tract irritation, short-term 

exposure to relatively low concentrations can 

also cause coughing and choking. Inhalation 

exposure of male volunteers to hydrogen 

chloride at concentrations between 50 and 

100 ppm for 1 hour were reported as barely 

tolerable, and 10 ppm was the maximal 

concentration acceptable for prolonged 

exposure. The NIOSH recommended exposure 

limit (REL), the OSHA permissible exposure 

limit (PEL), and the ACGIH threshold limit 

value (TLV) for hydrogen chloride are a ceiling 

limit of 5 ppm. The ACGIH TLV is based on 

the reports of respiratory irritation from 

short-term exposure to hydrogen chloride at 

5 ppm and above. NIOSH has also established 

an immediately dangerous to life and health 

(IDLH) value of 100 ppm for hydrogen 

chloride. A concentration of 309 ppm has been 

reported as the level of hydrogen chloride 

causing a severe toxic endpoint in laboratory 

animals, including intolerable irritation, 

incapacitation, and unconsciousness. For these 

reasons, NIOSH suggests that licensees who use 

this QLFT method investigate other options. 

5.6 Fit Test Protocols and Procedures 

5.6.1 Pre-Test Considerations 

Certain prerequisites must be met before any 

subject is allowed to wear a respirator, even

for fit testing. Major among these are medical 

screening and training in the use of the 

device(s) to be tested. Test subjects must also 

be clean-shaven for the fit test. 

People who are waiting around for fit testing 

may try to distract the fit test subject. This 

distraction may cause the subject to make 

facial or other movements that are not part of 

the protocol. Eliminate the possibility of the 

subject "clowning" with others by performing 

the fit testing in a private area. 

Subjects should perspire during the test in the 

same way that they will perspire in the 

workplace. Therefore, the facepiece should be 

donned approximately five minutes prior to 

the start of the test. This allows at least the 

facial perspiration process to begin prior to 

exposure to the challenge aerosol. 

5.6.2 The Protocol 

The word "protocol" is used generally to 

denote a procedure that requires strict 

adherence. Therefore, the fit-test protocol that 

is established for use in a respiratory 

protection program should be used 

consistently when performing measurements 

of the quality of respirator fits. The protocol 

covers everything about the measurement 

portion of the fit test. Once established, it 

should be followed whether a qualitative or 

quantitative test is used. The protocol should 

include one or more procedures that provide 

instructions on equipment operation and 

testing, test documentation, exercises to be 

performed during the test, recordkeeping, and 

so on. If both QLFT and QNFT are used, then 

two (or more) protocols will be needed.

5.6.3 The Exercises

The purpose of having a fit test subject 

perform various movements and exercises 

during respirator fit testing is to simulate those

NUREG/CR-0041, Revision I 80
movements which will likely take place on the 

job when respirators are being worn, and to 

see if the respirator provides adequate 

protection under these circumstances. It must 

be understood, however, that no respirator fit 

test can hope to duplicate all the possible 

workplace movements of a respirator wearer. 

It is also important to establish clearly how the 

chosen exercises are to be performed. If all 

test subjects perform each test exercise in 

approximately the same way, then valid 

comparisons can be made between the fit test 

results of different subjects, and between 

different types of respirators on the same test 

population. 

The exercises selected, and how those 

exercises are performed during testing, should 

be designed to challenge the respirator fit 

under simulated conditions of use. This should 

be an aggressive test, and not just "for the 

record." Fit-test protocols should not be 

designed simply to allow a high percentage of 

test subjects to "pass" the test. 

Listed below are the eight exercises specified 

in the OSHA respirator standard (29 CFR 

1910.134 Appendix A). Included are 

suggested instructions for performing each of 

the exercises to limit the variability between 

fit tests. Selecting the OSHA-required 

exercises is acceptable to the NRC. 

1. Normal Breathing. Subject should stand 

without talking and breathe normally with 

arms at sides. Head should be facing 

forward, eyes front. This should be both 

the first and last exercise during the fit 

test. 

2. Deep Breathing. In a normal standing 

position, take long, deep breaths. Do not 

breathe so rapidly as to cause 

hyperventilation, but attempt to simulate 

labored breathing in the workplace. Head 

should be facing forward, eyes front. 

3. Turn Head Side-to-Side. While standing 

and breathing normally, turn the head as 

far to one side as possible, keeping the

shoulders square and the trunk of the body 

facing front. With the head turned, take 

one normal breath and let it out. Then turn 

the head quickly all the way to the other 

side, and hold it there through one 

inhalation/exhalation cycle. Repeat this 

for the required duration of the exercise. 

The head should be turned quickly from 

one side to the other, but not so fast as to 

cause whiplash or other injury. No breath 

should be taken in between the full left 

and full right positions. Be sure that the 

subject is not moving from the waist and 

facing his upper body left and right. The 

purpose of this exercise (and of the Head 

Up and Down exercise below) is to stretch 

the skin on the neck, chin, and sides of the 

face to see how badly those movements 

degrade the respirator seal. 

4. Move Head Up and Down. While standing 

and breathing normally, move the head as 

far up as possible, keeping the shoulders 

square and the trunk of the body facing 

front. With the head elevated in this 

manner take in a normal breath and let it 

out. Then move the head all the way 

down, and hold it there through one 

inhalation!exhalation cycle. Repeat this 

for the duration of the exercise. The head 

should be moved quickly from one 

position to the other, but not so fast as to 

cause whiplash or other injury, or to cause 

the filter to hit the chest. No breath should 

be taken in between the full up and full 

down positions. Be sure that the subject is 

not moving from the waist and positioning 

his upper body up and down. 

5. Talk. Usually test subjects are required to 

read "The Rainbow Passage" (Appendix E 

to this Manual). This is an elocution drill, 

requiring the person who reads it aloud to 

form all of the vowel and consonant 

sounds in the English language. An 

alternative (for people who have forgotten 

their glasses) is to have them count 

backwards from 100, or recite a poem that 

they know. Whatever the words used in 

thlis exercise, the important thing is for the

81 NUREG/CR-0041, Revision I
subject to speak clearly, trying to make 

himself understood to the fit test 

administrator. The subject should not take 

a deep breath and read or recite at a rapid 

and unintelligible rate. He should speak 

slowly and enunciate each word, just as he 

will have to do in the workplace to make 

himself understood while wearing a 

respirator. 

6. Grimace. The test subject should breathe 

normally and grimace by smiling or 

frowning. During the smiling portion the 

comers of the mouth should turn upward, 

the brow should rise and the cheeks 

should broaden. When frowning, the brow 

should be knitted and the corners of the 

mouth turned downward in a scowl. The 

smile and frown should be alternated for 

the duration of the exercise. The grimace 

exercise is designed to break the face-to

facepiece seal to ensure that the seal is 

reestablished for the final two exercises. 

Therefore the fit factor results of the 

grimace exercise are not used to calculate 

the overall fit factor. This exercise should 

not be used during QLFT. 

7. Bend at Waist.4 While breathing normally, 

the subject should bend forward from the 

waist until the upper portion of the body is 

approximately parallel with the floor, as if 

trying to touch his toes. Keep the 

shoulders square. While in this position 

take in a normal breath and let it out. Then 

resume an upright position and repeat an 

inhalation/exhalation cycle. Continue 

alternating these two positions for the 

duration of the exercise. The movements 

should be accomplished quickly, but care 

must be taken not to bump the head or 

cause other injury. No breath should be 

taken in between the full up and full down 

positions. 

(Jog in Place. The feet should be lifted off 

the floor during this exercise, but it should 

not resemble an Olympic sprint. This 

4 Jogging in place should be substituted for bending over 

at the waist in those test environments that do not permit 

bending.

exercise should induce rapid respiration, 

similar to what would be experienced 

while climbing stairs, lifting objects, and 

performing other strenuous tasks in the 

work place. The test subject should break 

a sweat during this exercise.) 

8. Normal Breathing. As in 1. above. 

5.6.4 Duration of Exercises 

The duration of each exercise (except for the 

grimace exercise) should be one minute. This 

applies to both QNFT and QLFT protocols. In 

quantitative fit testing, there is some time 

delay between when the sample air is drawn 

from the facepiece and when it is evaluated by 

the test instrument. This is a function of how 

long the sample tube is, and of the sample air

flow rate. This time delay may be significant. 

There may also be some time delay between 

sample analysis and the display of that 

analysis on a meter or chart recorder. This 

time delay is generally short. The 

manufacturer's instructions for the test 

equipment should supply this information. The 

duration of each exercise, then, should be one 

minute plus any sample evaluation time delay. 

The grimace exercise, used only during 

QNFT, should only be performed for 

15 seconds.

NUREG/CR-0041, Revision 1 82
5.6.5 Acceptable Fit

The overall fit factor (FF) must meet or 

exceed the required fit factor for the type of 

device used. The fit factor for one or more 

exercises may be less than the minimum 

acceptable value as long as the overall fit 

factor is acceptable. The overall fit factor is 

calculated as follows: 

FFOverall = 

- + -- +... + 

FF, FF2 FE, 

Where n = the number of exercises performed 

5.7 Retesting 

The retest period does not need to be more 

frequent than annually. A retest grace period 

of ninety days is considered to be reasonable. 

Licensees should not interpret this grace 

period to mean that re-testing can be 

accomplished every 15 months. For example, 

three consecutive annual fit tests should not 

exceed 39 months. 

Retesting should be accomplished prior to 

next respirator use when a potential respirator 

wearer, since the last fit test, has: 

I. A weight change of 10% or more; 

2. Significant facial injury or scarring in the 

area of the facepiece seal; 

3. Significant dental changes (e.g., multiple 

extractions without prosthesis, acquisition 

of dentures); 

4. Reconstructive or cosmetic surgery in the 

area of the facepiece seal; 

5. Any other condition that might change the 

fit of a face-sealing respirator. 

It is the responsibility of the individual 

respirator wearer to bring these conditions to 

the attention of the RPA. 

Licensees are cautioned that some previous 

federal regulations applying to some non

radiological hazards (e.g., 29 CFR 1910.1001

Asbestos), and some proposed non

radiological respiratory protection regulations, 

have required or proposed re-testing at more 

frequent intervals, and have required or 

proposed more than one satisfactory fit test be 

achieved. NRC requires only one satisfactory 

fit test. 

5.8 Minimum Acceptable QNFT 

Fit Factors 

If quantitative fit testing is used to test 

facepieces that, in the field, will operate in the 

negative-pressure mode, a fit factor that is at 

least 10 times the APF (stated in Appendix A 

to 10 CFR 20) should be demonstrated before 

an individual is permitted to use that facepiece 

in the field. For combination devices (e.g., 

combination negative-pressure air purifying 

and continuous-flow airline device), the 

minimum acceptable fit factor is 10 times the 

APF for the negative-pressure mode of 

operation. If quantitative fit testing is used to 

test facepieces that in the field will operate 

only in the positive-pressure mode (e.g., 

powered air-purifying respirators), or in the 

continuous-flow mode (e.g., airline 

respirators), or in the pressure-demand mode 

(e.g., airline respirators, SCBA), a fit factor of 

at least 500 should be demonstrated with the 

facepiece operating in the negative pressure 

mode before an individual is permitted to use 

that facepiece in the field. Table 5-1 is 

provided below for convenience, but licensees 

are reminded that the source of APFs is 

Appendix A to 10 CFR 20. During training or 

operation, perceptible outward leakage of 

breathing gas from the face-to-facepiece seal 

area of any self-contained breathing apparatus 

is unacceptable, and the wearer should not be 

permitted to continue to use the device.

83 NUREG/CR-0041, Revision I
Table 5-1. Respirator APFs and required minimum fit factors.

5.9 Sanitizing Respirators After Use 

in Fit Testing 

Licensees have an obligation to provide each fit

test subject with a clean, sanitary respirator. 

Precisely how this is accomplished is left to the 

judgment of the RPA, but (s)he should consider 

consulting an industrial hygienist or nurse 

before deciding on the method to be used. 

Licensees may consider one of the following 

methods for use in their fit test programs. 

I. Use a different facepiece for each subject, 

then wash and sanitize all used facepieces at 

the end of the day or shift. This requires a 

relatively large number of facepieces to be 

dedicated to fit testing. 

2. At the end of each fit test, the test subject 

sanitizes the facepiece just used, making it 

ready for another test subject. This could be 

done by immersing the respirator in a

solution of water and one of the sanitizing 

solutions described in this manual, or by 

spraying such a solution into the inside of 

the facepiece. The facepiece should then be 

thoroughly rinsed in clean water, then 

shaken and towel dried. 

3. Require each test subject to sanitize the 

facepiece that (s)he will use during the fit 

test. This could be done as described in 2. 

above. 

4. Wiping the interior surfaces with a non

alcohol sanitizing towelette might be 

acceptable if the concurrence of an 

industrial hygienist is obtained. 

Several respirator manufacturers have adapters 

available that will convert any of their 

facepieces into a fit-test respirator. If this is the 

case, personnel could be given ready-for-issue 

respirators for use in fit testing, then return them

NUREG/CR-0041, Revision 1

Respirator Type Mode APF Required Fit Factor 

AIR-PURIFYING 

Single-use disposable NP I NR 

Facepiece, half mask NP 10 100 

Facepiece, full NP 100 1000 

Facepiece, half mask PP 50 500 

Facepiece, full PP 1000 500 

Helmet/hood PP 1000 NR 

Facepiece, loose-fitting PP 25 NR 

ATMOSPHERE SUPPLYING 

Air-line respirator 

Facepiece, half-mask D 10 100 

Facepiece, half-mask CF 50 500 

Facepiece, half-mask PD 50 500 

Facepiece, full D 100 1000 

Facepiece, full CF 1000 500 

Facepiece, full PD 1000 500 

Helmet/hood CF 1000 NR 

Facepiece, loose-fitting CF 25 NR 

Suit CF I NR 

Self-contained breathing apparatus 

(SCBA) 

Facepiece, full D 100 1000 

Facepiece, full PD 10,000 500 

Facepiece, full RD 100 1000 

Facepiece, full RP 10,000 500 

NR = Not required

84
to the respirator washing area when the fit test is 

complete. 

5.10 Communication 

5.10.1 Need for Voice-Amplification 

Equipment 

Facepiece respirators are drawn up snug 

against the wearer's face to provide a proper 

facepiece-to-face seal. The limitation on jaw 

movement that results, combined with the 

muffling effect of the facepiece, can severely 

inhibit voice communication. Add to this the 

complications of the workplace, such as high 

ambient noise levels and the distance between 

workers, and communication attempts can 

become very stressful. Voice strain, hoarsness, 

and frustration are the primary physical 

manifestations, but the potential for accidents 

and mistakes is significantly increased when 

clear communication is difficult. 

5.10.2 Respirator Manufacturer-Supplied 

Equipment 

Some respirators incorporate a speaking 

diaphragm into the facepiece that vibrates as 

the wearer speaks and helps to transmit the 

sound outside the facepiece. Mask-mounted 

microphones, connected to external amplifiers 

are also available for many respirators. The 

licensee must ensure that any voice 

amplification device is listed on the NIOSH 

list of approved subassemblies. 

5.10.3 Non-Respirator Manufacturer

Supplied Equipment 

Other suppliers have available a variety of 

products offering communication aids to 

respirator wearers. These include throat

mounted microphones, in-the-ear 

microphone/receivers, cranial mikes, 

headset/boom devices, and all sorts of

combinations of communication equipment 

for all conditions of use. When using 

communications equipment supplied by 

companies other than the respirator 

manufacturer, care must be taken that use of 

the device does not void the NIOSH approval 

of the respirator. Generally speaking, 

equipment used in conjunction with a 

respirator cannot affect its form, fit or 

function. It cannot be attached to the 

respirator, and may not interfere with how the 

respirator fits on the face or head. For 

example, a bone conduction microphone worn 

under the head harness of a full facepiece (to 

hold it firmly in contact with the wearer's 

head to get maximum sound conduction) 

would likely void the NIOSH approval since it 

would interfere with the way the respirator is 

worn. A throat-mounted microphone would 

not void the approval, since it does not come 

into contact with the respirator in any way. 

5.10.4 Other Options 

Hand signals can work well in situations 

where communications do not need to be very 

complex. Thorough planning of work and 

mock-up training may also limit the need to 

communicate on the job. Other possible 

alternatives to voice amplification equipment 

might be the use of signaling devices such as a 

horn or bell. These might be appropriate for 

communicating simple instructions or warnings 

to workers. The important considerations are 

worker safety and ALARA. The RPA should 

make the judgment about the adequacy of 

communication methods used. 

5.11 Vision and Vision Correction 

In most full facepiece-type respirators, the 

worker's field of vision is limited. If care is 

not taken, the worker can literally walk into an 

accident.

85 NUREG/CR-0041, Revision I
Workers should be cautioned that if they are 

unable to safely perform their assigned tasks 

while wearing respirators without vision 

correction, then they should not be issued 

respirators until respirator spectacle adapters 

with proper corrective lenses are in hand, or 

unless they are wearing their contact lenses. 

Licensees should ensure that individuals who 

need to wear corrective lenses while performing 

licensed duties (e.g., power reactor licensed 

operators), or while responding to an emergency 

(e.g., fire brigade members) should have proper 

corrective lenses available for conditions 

requiring use of a respirator or a self-contained 

breathing apparatus.5 

Any spectacle adapter, even those not supplied 

by the manufacturer of the respirator, may be 

acceptable for use inside a full facepiece 

respirator. Any adapter may be used if the 

device does not interfere with the facepiece seal, 

if it does not cause any distortion of vision, 

damage the lens or the facepiece itself, or cause 

any physical harm to the wearer during use. 

Contact lenses may be worn by wearers of full 

facepiece respirators, supplied-air hoods, 

helmets and the like. Licensees may not require 

workers to obtain contact lenses, and contact

lens wearers should not be forced to wear the 

contact lenses in lieu of a standard spectacle 

adapter. Contact-lens wearers should be 

informed during training that they should wear 

their contact lenses during the hands-on portion 

of the respirator training and during fit testing to 

ensure compatibility. 

New contact-lens wearers (i.e., those with little 

or no experience wearing the contact lenses 

under any circumstances) might be instructed 

not to wear the new lenses while wearing a 

respirator until they have several weeks 

experience using the contact lenses. Wearing the 

contact lenses during training or fit testing 

- NRC Information Notice 97-66: "Failure to Provide 

Special Lenses for Operators Using Respirator or Self

Contained Breathing Apparatus During Emergency 

Operations."

should be viewed as an absolute minimum 

level of experience. 

It is the obligation of the contact-lens wearer 

to make known to the licensee problems 

experienced with contact lenses and respirator 

use. The NRC's position on contact lens use 

with respirators is contained in Regulatory 

Guide 8.15, Section 5.7, and is consistent with 

the OSHA rule. 

5.12 Use of Respirators in 

Low Temperatures 

5.12.1 Lens Fogging 

Lens fogging in negative-pressure, air

purifying respirators is a continual problem. 

Though respirator manufacturers are required 

by NIOSH to incorporate design features to 

reduce or eliminate the effect of fogging, most 

are less than fully effective. Most full

facepiece respirators have inlet ducts or 

air-directing devices that cause the inhaled air 

to be swept across the inside of the facepiece 

lens. This acts much like an automobile 

defroster, which clears off (with varying 

degrees of success) the accumulated 

condensation on the inside of the respirator 

lens. The cause, of course, is the warmed and 

moistened exhaled breath that comes into 

direct contact with the inside of the colder 

lens. As the ambient air temperature 

decreases, the intermittent lens-clearing 

provided during inhalation becomes less and 

less effective. At temperatures below the 

freezing point, lens frosting can occur, which 

can completely obliterate the wearer's vision. 

Workers are known to sometimes force deep 

and extended inhalations to provide clear 

vision. As long as they can hold their breath, 

the lens will stay relatively condensation-free. 

This cycle of deep inhalation followed by 

breath-holding is physically taxing and should 

be discouraged.

NUREG/CR-0041, Revision I 86
Nosecup inserts, available for most brands of 

full facepieces, are very effective at directing 

the moisture-laden exhaled breath away from 

the lens and into the exhalation valve. At 

temperatures below 32 OF, nosecups (or an 

alternative method of control) are required as 

part of a NIOSH-approved assembly in all 

self-contained breathing apparatus. Powered 

air-purifying devices and constant-flow airline 

devices also offer some reduction to the 

fogging problem. 

There are some specialty products on the 

market that can effectively reduce or eliminate 

lens fogging. Plastic inserts that adhere 

directly to the inside of the lens and form a 

double-pane barrier are said to work very well. 

These would not have to be supplied by the 

facepiece manufacturer so long as they do not 

interfere with the facepiece seal, do not cause 

any distortion of vision, damage the lens of the 

facepiece or the facepiece itself, or cause any 

physical harm to the wearer during use. This 

judgment is to be made by the RPA. 

Anti-fog solutions can be effective if applied 

in accordance with their instructions. Check 

with the respirator manufacturer regarding 

compatibility of these products with their 

facepieces. 

SCUBA divers apply some saliva to the inside 

of their diving masks to limit fogging. As long 

as facepieces are cleaned and sanitized before 

being used by another person, this technique is 

acceptable in an NRC-regulated program. 

5.12.2 Exhalation Valve Freezing 

Very low temperatures can also cause the 

respirator exhalation valve, moistened with 

condensation or saliva, to freeze in the open

position, thus providing a pathway for gross 

leakage of contaminants into the facepiece. 

Use of a powered air-purifying respirator or a 

continuous-flow, supplied-air respirator 

eliminates the potential for a frozen exhalation 

valve since these are positive-pressure devices 

and the exhalation valve is always in the open 

position during operation. 

5.13 Wearer Comfort and Acceptance 

Comfort relates to the degree of physical 

distress to the respirator wearer. Everyone who 

wears a respirator may be expected to 

experience some discomfort. Distress 

associated with the job environment tends to 

be accentuated by wearing a respirator: vision 

is restricted, breathing is more difficult, 

ventilation across the face is limited, 

equipment may be cumbersome and restrict 

movement, and wearing the respirator may 

add to the adverse effects of temperature 

extremes. Other factors also adversely affect 

wearer acceptance. An improperly fitted mask 

may create intolerable pain spots. Improperly 

designed or malfunctioning valves may cause 

uncomfortable restrictions to breathing or 

produce an irritating flicking and popping 

sound. Limitations on the wearer's ability to 

communicate may be unpleasant and add to 

the hazards. All these factors contribute to the 

physical discomfort that affects the 

willingness to wear and make proper use of 

respirators. However, if proper attention is 

paid to these factors in selecting equipment, 

most people may be provided with respirators 

that do not cause undue distress and that 

provide effective protection. The more 

comfortable a respirator is, the more likely 

that it will be worn properly and for the 

duration of the work.

87 NUREG/CR-0041, Revision I
References and Resources

1. Hodous, Thomas K., MD. "Screening Prospective Workers for the Ability to Use Respirators." 

Journal of Occupational Medicine, Vol. 28, No. 10, October, 1986, pp. 1074-1080. 

2. Hodous, Thomas K. and Mary Kay White. "Reduced Work Tolerance Associated with Wearing 

Protective Clothing and Respirators." American Industrial Hygiene Journal, Vol. 48, April, 1987, pp. 

304-310. 

3. Petty, Thomas L. MD. "Spirometry: A Simple but Accurate Gauge of Cardiopulmonary Health." 

Occupational Health & Safety, April, 1989, pp. 40-45Bloom, E.B., J.D. Carb, C.J. MacLean, et al. 

"Pulmonary Function as a Predictor of Coronary Heart Disease." American Journal of Epidemiology, 

1989; 129: 97-104. 

4. Hodous, Thomas K., John L. Hankinson and Gregory P. Stark. "Workplace Measurement of 

Respirator Effects Using Respiratory Inductive Plethysmography." American Industrial Hygiene 

Journal 50 (7): 372-378 (1989). 

5. NFPA 1500 Standard on Fire Department Occupational Safety and Health Program. Quincy, MA: 

National Fire Protection Association, 1992. 

6. Standard on Open-Circuit Self-Contained Breathing Apparatus for Fire Fighters. Quincy, MA: 

National Fire Protection Association, 1981. 

7. American National Standard Practices for Respiratory Protection for the Fire Service. New York, 

NY: American National Standards Institute, ANSI Z88.5- 1981. 

8. NIOSH [1990]. NIOSH Pocket Guide to Chemical Hazards. Cincinnati, OH: U.S. Department of 

Health and Human Services, Public Health Service, Centers for Disease Control, National 

Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 90-117. 

9. NIOSH [1987]. NIOSH Respirator Decision Logic. Cincinnati, OH: U.S. Department of Health 

and Human Resources, Public Health Service, Centers for Disease Control, National Institute for 

Occupational Safety and Health, DHHS (NIOSH) Publication No. 87-108. 

10. Bollinger N.J., Schutz RH [1987]. NIOSH Guide to Industrial Respiratory Protection. Cincinnati, 

OH: U.S. Department of Health and Human Resources, Public Health Service, Centers for 

Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) 

Publication No. 87-116. 

It. Marsh, J.L. [1984]. Evaluation of Irritant Smoke Qualitative Fitting Test for Respirators. Am Ind 

Hyg Assoc J 45:245-249.4516. 

12. IE Information Notice No. 84-24: "Physical Qualification of Individuals to Use Respiratory 

Protective Devices," dated April 5, 1984, describes a fatality involving a worker who had been 

wearing a respirator, and provides guidance on medical screening programs for respirator users. 

13. G.D. Kerr et al. "Health Physics Positions Data Base," Health Physics Position 219, NUREG/CR

5569, Revision 1, Page 120, February 1994. 

14. NRC Information Notice 97-66: "Failure to Provide Special Lenses for Operators Using 

Respirator or Self-Contained Breathing Apparatus During Emergency Operations." August 20, 

1997. 

15. OSHA (August 3, 1998) Memorandum to All Regional Administrators from John B. Miles, Jr., 

Director. "Questions and Answers on the Respiratory Protection Standard."

NUREG/CR-0041, Revision I 88
6 SAFETY

6.1 Face-to-Facepiece Seal Integrity 

The single most important thing that a 

respirator wearer has control over is the 

integrity of the face-to-facepiece seal. 

Respirators that rely partially or completely on 

a face-to-facepiece seal may never be worn by 

individuals who have facial or other hair that 

intrudes into the area where the facepiece is 

supposed to contact or seal to the face. This 

applies to both men and women, and to both 

positive- and negative-pressure devices. Also, 

the fit of some loose-fitting facepieces might 

be adversely affected by facial hair. This 

should be evaluated by the RPA. 

Cosmetics, medicines, ointments and any 

other material applied to the face in the area 

where the facepiece seals to the face precludes 

respirator use while such material remains in 

place. Acne scars and other permanent facial 

deformities should be dealt with during fit 

testing. If the test subject is able to meet the 

fit-test criteria, then respirator use may be 

allowed. Skin eruptions, boils, and other 

transitory skin conditions should 

contraindicate respirator use while the 

condition is manifest, but only until the skin 

has recovered. 

Protective hoods should be worn over the 

respirator suspension straps. Skull caps, 

surgeon caps and the like should not be worn 

under the suspension straps. Hard hats and 

other protective equipment and protective 

clothing, if worn, should not interfere with the 

form, fit or function of the respirator. Even 

spectacle adapters that utilize an ultra-thin head 

band of elastomeric material to hold them in 

place on a worker's face may not be used in an 

NRC-regulated respiratory protection program. 

This prohibition against any material or 

substance over which the wearer has control in 

the area where a tight-fitting or loose-fitting

respirator is designed to contact or seal to the 

face of the wearer is intended to be all

inclusive. NOTHING should exist between the 

skin of the respirator wearer and the sealing 

surface of the facepiece. There are no 

exceptions. OSHA and ANSI also have strong 

prohibitions against facepiece seal 

interference. 

6.2 Standby Rescue Persons 

Standby rescue persons are needed in two cases. 

First, standby rescuers should be present when a 

respiratory protection device is used that would 

be difficult or impossible for the wearer to 

remove unaided in case of failure of the air 

supply. Individuals using this type of equipment 

are in a confined space. Since one standby 

person could conceivably assist several persons, 

the ratio need not necessarily be I to 1. Standby 

rescue persons are also required when 

individuals enter an IDLH environment. In 

certain circumstances, such as the fatality 

involving a diver in an inerted condensate 

storage tank described below, two standby 

persons were not enough to pull the 

unconscious diver up and out of the tank. The 

respirator program administrator (RPA) or other 

competent persons are to decide the appropriate 

ratio of standby workers to those entering the 

IDLH area. Making equipment-such as tripods 

and power winches-available might also be 

considered in certain circumstances. The 

purpose of a standby rescue person is not to 

simply fulfill a legal requirement. Rather, it is to 

be able to effect a rescue if that becomes 

necessary. 

Licensees should refer to OSHA's requirements 

for entry into permit-required confined spaces 

(29 CFR 1910.146), and requirements for entry 

into IDLH environments (29 CFR 

1910.134(g)(3)).

89 NUREG/CR-0041, Revision I
6.3 Un-Assessed Environments 

An air sample does not necessarily need to be 

taken in each area prior to each entry by 

personnel. Areas where the licensee is 

reasonably certain that airborne contamination 

concentrations are low need not be sampled 

prior to each entry. This should already be 

addressed in the licensee's air sampling 

program. 

When prompt entry into an area is necessary 

and there is reason to believe that significant 

levels of airborne radiological contamination 

might be present, entry may be made by 

personnel equipped with any appropriate 

respiratory protection device, so long as the 

area is known to not be IDLH due to the 

presence of non-radiological hazards. Good 

practice suggests that the device selected in 

this situation have as high an APF as 

practicable, consistent with ALARA and good 

safety practice. This decision should be made 

by the RPA or other competent individual. 

If entry is to be made into an un-assessed area 

that could reasonably be expected to contain 

an IDLH environment, then it should be 

considered to be IDLH for purposes of 

assigning respirators and standby personnel. 

RPAs are encouraged to err on the side of 

caution in these situations. 

6.4 Emergency Escape 

The emergency escape devices envisioned 

here are those that would either be carried by 

workers or staged at critical locations inside 

work areas for use during escape from an 

environment in which respirators are normally 

not required. In radiological environments 

these could be any of the devices listed in 

Appendix A to 10 CFR 20. For potentially 

IDLH environments, only those certified by 

NIOSH for use in IDLH environments should 

be used. These devices are identified on the 

NIOSH certificate. Devices should be selected 

so that they are easy to don and use, and do

not slow the workers down as they are making 

their escape. When deciding how many of 

these devices to stage in a potentially IDLH 

area, licensees should take into account the 

fact that many more devices will be needed 

than the number of individuals who might be 

present when an emergency occurs. A person 

in a potentially IDLH area should never be far 

from an escape device. 

Emergency escape devices staged or carried 

into areas could be negative-pressure devices 

equipped with particulate or other types of 

chemical cartridges or canisters. They might 

also be small, constant-flow, self-contained 

breathing apparatus with a simple bag-type 

respiratory inlet covering. 

The decision about which type(s) of 

emergency escape respirators to stage or have 

workers carry into these areas should be based 

on the potential hazards in the area and the 

potential concentration based on the worst 

credible accident scenario. 

Potential wearers of these devices should have 

sufficient training to enable them to know 

when to use the devices, how to don and use 

the device correctly and efficiently, and how to 

make their escape. They should also be 

informed that these devices are for escape 

only, and are not to be used for fire fighting, 

search and rescue, or other entries into 

hazardous areas. 

No medical screening or fit testing is required 

for personnel who are not respirator wearers, 

but who might-in an emergency-need to use 

an emergency escape respirator.

NUREG/CR-0041, Revision 1 90
6.5.2 Breathing-Air Quality

6.5.1 Breathing-Air Systems 

Licensees are required by 10 CFR 20.1703(g) 

to supply air of Grade D quality or better as 

described by the Compressed Gas Association 

(CGA) to each supplied-air respirator. Section 

6.5.2 addresses breathing-air quality. 

Licensees who utilize a service-air or 

instrument-air system as a source of breathing 

air need to maintain extra vigilance to prevent 

radiological and non-radiological contamination 

of the system. Licensees in this situation should 

consider the use of removable spool pieces in 

the pipes leading to fluid systems that are 

connected to the air system to prevent back-flow 

into the air system when not in use. If this is not 

practicable, a check valve between two isolation 

valves, or two isolation valves with an open 

leak-off between can be used. The use of check 

valves alone is the least desirable option in this 

situation because of their tendency to eventually 

develop leaks. IE Information Notice 79-08 

describes an incident where both a check valve 

and a ball valve leaked and allowed the 

contamination of a breathing-air system. IE 

Information Notice 85-06 describes two similar 

air system contamination incidents. A complete 

list of respirator-related generic 

communications has been included at the front 

of this Manual. 

Caution should be exercised if temporary air 

compressors, powered by internal combustion 

engines, are utilized to supplement the installed 

air compressors, or used where no installed air 

system is operational. In these cases, the 

licensee should ensure that the engine exhaust is 

not drawn into the compressor intake. 

Licensees should not permit use of breathing-air 

supply hoses, regulators or other components 

for non-breathing-air applications. Quick

connect fittings used for breathing-air 

equipment should be incompatible with quick

connect fittings used for other purposes at the 

facility. This is an OSHA requirement [29 CFR 

1910.134(i)(8)].

The breathing-air supply should meet certain 

minimum quality requirements. These are 

specified in the CGA pamphlet G7.1-1997 

"Commodity Specification for Air." This 

document also describes acceptable test 

methods for measuring the parameters. 

Documentation of analytical results and test 

methods should be retained. If analysis results 

are provided by a vendor, the licensee should 

take steps to assure the accuracy of the 

reported results. 

6.5.3 Moisture Content in Breathing-Air 

Cylinders 

The allowable moisture content in breathing

air cylinders is addressed in the OSHA 

regulations [29 CFR 1910.134(i)(4)(iii)]. This 

requires that the moisture content in the 

cylinder does not exceed a dew point of-50 'F 

(-45.6 'C) at 1 atmosphere pressure. CGA 

G-7.1-1997 states that air in SCBA cylinders 

should not exceed a dew point of-65 'F 

(24 ppm v/v), or 10 'F lower than the coldest 

temperature expected in the area where the 

SCBA will be used. Licensees should comply 

with the OSHA requirement as a minimum, 

and should meet the CGA Grade L 

requirement for moisture content if practical. 

6.5.4 Testing Frequency 

Guidelines for the frequency at which 

breathing-air supply systems should be tested 

are provided in Regulatory Guide 8.15, 

"Acceptable Programs for Respiratory 

Protection," Revision 1 (October 1999). As long 

as reasonable precautions are taken to protect 

the air inlet, an air system supplied from a non

oil-lubricated compressor that is used 

exclusively to supply breathing air is less likely 

to become contaminated than a combination 

service-air/breathing-air system. It is reasonable, 

then, to test the air quality less frequently in a 

dedicated system. In systems that utilize

NUREG/CR-0041, Revision I

6.5 Breathing Air

91
compressors that are oil-lubricated, additional 

potential sources of contamination are present 

and more frequent testing is indicated. Air 

systems that are used daily or several times in a 

week to supply breathing air should be tested 

more frequently than a system used 

infrequently. Systems used infrequently to 

supply breathing air should be tested before 

each use, then at some reasonable frequency 

during the time it is in use. A system that is due 

for testing, but which is not in use, need not be 

activated for purposes of air-quality testing, so 

long as the testing is accomplished before the 

system is used again to supply breathing air. 

Likewise with combination service

air/breathing-air systems. If the system is not 

being used to supply breathing air it need not be 

tested periodically (e.g., monthly or quarterly) 

for Grade D quality, so long as the testing is 

done prior to its next use as a source of 

breathing air. Results from these "prior to next 

use" tests should be in hand, however, before 

the system is used to supply breathing air. 

The air from compressors used to supply 

breathing air to cylinders should also be tested 

periodically. This applies to SCBA cylinders 

and to larger cylinders (e.g., 280 ft3 or 300 ft3), 

and to cylinders filled by the licensee and to 

those filled by a vendor. If the air is tested and 

shown to meet the quality criteria at the 

beginning of the filling process, it is 

reasonable to assume that cylinders may be 

filled for the following 24 hours without 

retest. Other reasonable retest periods may be 

acceptable. 

6.5.5 Test Methods 

The test methods described in CGA G7.1

1997 are acceptable to the NRC staff. Air

quality tests performed using detector tubes 

filled with color-reactive chemicals that are 

sensitive to oxygen and the various possible 

contaminants are acceptable, if performed in 

accordance with the manufacturer's 

instructions. Licensees who use this method 

for routine air-quality verification should have

the air tested several times per year using 

more rigorous analytical methods (e.g., gas 

chromatography). 

6.5.6 Sampling Breathing Air for 

Radiological Contamination 

Licensees should take steps to protect 

breathing-air manifolds, quick-connect 

fittings and other potential places where 

radiological contaminants might enter a 

breathing-air system. Caps, plastic bags, and 

tape have been used successfully in this 

application. Wipe samples should be taken at 

the air-connection points that might be 

contaminated prior to attaching a respirator 

supply hose. The breathing air should be 

sampled periodically for radiological 

contaminants. One possible sampling method 

is illustrated in Figure 6-1. 

6.5.7 Oxygen Purity Requirements 

When any respiratory protection device uses 

an oxygen supply rather than an air supply 

(e.g., closed-circuit SCBA), that oxygen 

should meet the United States Pharmacopoeia 

(USP) requirements for medical or breathing 

oxygen. 

6.6 Use of Higher or Lower APFs 

Licensees who want to use APFs larger than 

the ones listed in Appendix A to 10 CFR 20 

must first apply to NRC and be granted 

permission (10 CFR 20.1705). Such 

applications should be in the form of a letter 

accompanied by a brief report. The report 

should describe the situation for which the 

higher APFs are needed and include the reason 

that an existing NIOSH-certified device with a 

larger APF is not suitable. It should 

demonstrate that the proposed respiratory 

protection equipment provides these higher 

levels of protection under the intended

NUREG/CR-0041, Revision I 92
Figure 6-1. Sample collection design for a radiological sample of the breathing-air supply.

conditions of use. This demonstration can be 

based on testing done by the licensee or the 

licensee's representative, or on testing 

performed by the manufacturer of the device. 

If only manufacturer testing has been done, a 

licensee representative should have observed 

or participated in such testing. 

Use of lower APFs for negative-pressure 

devices is permitted but not encouraged. 

Assigning a lower APF because a worker is 

unable to achieve a sufficiently high fit factor is 

not a good reason, and a different size facepiece 

should be tried. Furthermore, if an individual is 

unable to obtain a fit factor of >500 on a 

facepiece that will be used with a SCBA, that 

individual should not be permitted to use the 

SCBA for fire fighting, emergency response, 

rescue, or in IDLH atmospheres. 

No permission from or notification of the NRC 

is required or suggested for using lower APFs, 

but a record should be made and retained. An 

acceptable record could be made on the 

radiation work permit, as an annotation on a

work procedure, or in a brief memo retained in 

the work package. 

6.7 Limiting Duration of Respirator Use 

6.7.1 Introduction 

One of the most difficult tasks that an RPA has 

is to decide maximum duration of respirator use, 

or how long a worker should be asked to wear a 

respirator without a break. 

The primary reason for limiting the occasions 

when respirators might be used, and for 

limiting the duration of each respirator use, is 

personal safety. Each time an individual dons 

a respirator, some increment of risk is 

incurred. This risk could be the result of a 

limited or distorted field of vision, a 

diminished ability to hear or be understood 

clearly, tangling of an air-supply hose, 

inability to exit through a narrow opening, and 

so on. Limiting respirator use is part of a 

holistic approach to worker safety and should

93 NUREG/CR-0041, Revision I
include all aspects of personnel protection in 

the workplace. 

NRC regulations require' that each worker be 

instructed that (s)he is permitted to exit a work 

area for relief from respirator use in the event 

of equipment malfunction, physical or 

psychological distress, procedural or 

communication failure, significant 

deterioration of operating conditions, or for 

any other reason without obtaining prior 

supervisory permission. This, however, does 

not always provide a sufficient degree of 

assurance that workers will not exceed their 

subjective stress limit. Some individuals will 

persist at a task until they are well beyond the 

point at which they should have sought relief. 

This may result from peer pressure or from a 

misunderstanding of material presented 

during training. Listed below are some things 

that should be taken into account in determining 

maximum respirator use times. 

6.7.2 Establishing Time Limits 

In addition to the ability of each worker to 

obtain relief from respirator use at any time 

(10 CFR 20.1703(d)), licensees should set 

reasonable time limits on respirator use that 

apply to all workers. Factors that should be 

taken into account in setting these time limits 

should include consideration of the following 

as a minimum: 

"* Ambient temperature and humidity; 

"* Energy expended by the worker 

performing the task; 

"* Weight, thickness, permeability of anti

contamination clothing; 

"* Number of layers of anti-contamination 

clothing; 

"* Additional protective equipment worn; 

"* Work rate; 

"* Regional climate; 

"* Time of day; 

"* Time of year; and 

"* Other appropriate factors.

Licensees should establish reasonable limits 

on the time any individual should be expected 

to wear a respirator and on the number of 

times or hours per day or per week respirator 

use should be permitted. Since the stress and 

strain placed on workers by negative-pressure 

face-sealing respirators is generally much 

greater than for other types of devices (e.g., 

positive pressure), time limits on the use of 

negative-pressure respirators will usually be 

the most restrictive. These guidelines may 

impose limits using combinations of the 

following methods. 

"* Maximum continuous use time (e.g., no 

more than 30 or 60 or 120 minutes at a 

time); 

"* Maximum use time per hour (e.g., 15 or 

30 or 45 minutes per hour); 

"* Maximum daily use times (e.g., no more 

than 2 or 4 or 5 hours per day); or 

"* Maximum weekly use times (e.g., no more 

than 10 or 15 or 20 hours per week). 

For example, under a given set of 

circumstances (e.g., work rate, workplace 

temperature and humidity) a licensee might 

decide to limit each worker's use of negative

pressure respirators as follows: 

"* No more than 90 minutes at a time with a 

30-minute break between uses; 

"* No more than three 90-minute respirator 

use periods should be assigned in any 

working shift; and 

"* The maximum weekly respirator use time 

should be 18 hours. 

Under a different set of circumstances, 

another licensee might limit respirator use to 

30 minutes per hour, not to exceed six use 

periods in a working shift. Other reasonable 

methodologies for limiting respirator use 

times may be acceptable. The time limits used 

in the examples above should not be 

interpreted as NRC's suggestions or 

recommendations.

NUREG/CR-0041, Revision I

'10 CFR 20.1703(d).

94
6.9.1 Air Sampling

Different types of respirators impose various 

degrees of discomfort or stress on workers. The 

maximum use time for a worker performing 

moderately demanding work while wearing a 

full-facepiece air-purifying respirator in a hot, 

humid work area might be only 15 minutes 

every hour. A worker in a supplied-air hood or 

powered air-purifying respirator in a less 

stressful work environment and working at a 

slower rate might have a much longer effective 

work time. The NRC recognizes these variables 

and relies on the judgment of the RPA and other 

competent persons to set reasonable limits or 

guidelines. 

6.8 OSHA Requirements 

The ideal situation for licensees who must 

comply with the regulations of both OSHA and 

NRC when designing and implementing a 

respiratory program would be for the 

regulations to be compatible. This would allow 

a single program to be implemented rather than 

require that two different programs be run in 

parallel. The NRC believes that this has 

effectively been accomplished with the 1999 

amendment to 10 CFR 20 Subpart H and 

Appendix A, and Revision I to Regulatory 

Guide 8.15. The differences between the OSHA 

and NRC requirements pointed out in 

Regulatory Guide 8.15, Revision 1, Section 6.8 

are believed to be slight. 

6.9 Radiological Hazard Evaluation 

Air sample results may be used to determine 

which respirator (if any) should be assigned in a 

given work area. Air samples that are 

representative of the air breathed by workers 

may be used to estimate and assign CDE and 

CEDE.

Pre-exposure air sampling is not required in an 

emergency. The word "emergency" should be 

clearly defined by the licensee so that all 

personnel in decision-making positions 

understand what is and what isn't an 

emergency. True emergency situations would 

certainly include lifesaving, rescuing injured 

personnel, fire fighting, prevention of 

overexposure of an individual(s) to radiation, 

stopping or preventing a significant 

uncontrolled release of radioactive material. 

Appropriate air sampling or assessment is 

required in most other situations, at least 

where airborne radioactive material might 

exceed certain concentrations. The licensee 

should refer to Regulatory Guide 8.25 "Air 

Sampling in the Workplace," Rev. 1, June 

1992, and to NUREG-1400, "Air Sampling in 

the Workplace," September 1993 for 

information on acceptable air sampling 

practices. 

6.9.2 Noble Gases 

As stated in footnote f to Appendix A in 

10 CFR 20, exposure to noble gases is not 

considered to be a significant respiratory 

hazard. Only a small fraction of the TEDE is 

delivered by the gas in the lungs, while the 

majority comes from the cloud of gas in which 

the worker is present. Therefore, protective 

actions for these contaminants should be based 

on external (submersion) dose considerations 

(e.g., limiting exposure time). Noble gas 

concentrations should not be factored into 

DAC calculations for the purpose of deciding 

whether or not to assign respirators. 

6.9.3 Tritium Vapors 

A discussion of airborne tritium and how the 

APFs of various respirators are affected by it 

is included in paragraph 4.9.1 above.

NUREG/CR-0041, Revision 1

6.7.3 Variables

95
Tritium, normally found in the form of water 

vapor (3

H20) but sometimes present in 

gaseous form, requires special consideration. 

Air-purifying respirators provide little 

protection against airborne gases and vapor. 

Therefore if airborne tritium is present in the 

work area in sufficient concentration to require 

use of respiratory protection devices, then an 

atmosphere-supplying device should be 

selected. Unfortunately, approximately one

third of tritium intake occurs by absorption 

through the skin, so that by simply protecting 

the respiratory tract, only two-thirds of the job 

has been done. Therefore, the assigned 

protection factors allowed for atmosphere

supplying devices are lower for tritium than 

for other contaminants. These are provided in 

Table 4-19. 

In situations where tritium is detectable in 

significant concentrations in addition to 

airborne particulates, separate protection 

factors may need to be tracked or applied at 

the same time. The APF from Appendix A to 

10 CFR 20 would be applied for the 

particulate component of the air, and a greatly 

reduced APF would be applied for the tritium 

component. The APF for tritium could, for the 

sake of simplicity, also be applied to the 

airborne particulate component. 

Whole body-covering suits might be 

considered for some additional protection 

against skin absorption of tritium; however, 

most plastic suits are not impervious to tritium 

and a great deal of success should not be 

anticipated. The prudent course of action is to 

track DAC exposure hours using the reduced 

APF as outlined above. By use of post

exposure bioassay, actual exposure can be 

determined and the DAC-hour totals can be 

adjusted based on this bioassay information. 

6.10 Non-Radiological Hazard Evaluation 

In addition to radioactive respiratory hazards, 

there are non-radioactive respiratory hazards 

present in the nuclear industry that could 

present a hazard to personnel and the facility,

reduce the ability to maintain effective control 

over operations, and hinder efforts to mitigate 

consequences of safety system malfunction. 

Damage control and repair teams should be 

able to perform essential emergency duties at 

any time to restore plant systems and stabilize 

the plant so that recovery operations can take 

place when needed. Methods used to evaluate 

and control non-radioactive respiratory 

hazards are essentially the same as those used 

for radioactive hazards. Even a brief, 

unprotected exposure to some non

radiological respiratory hazards can lead to 

immediate permanent injury or death (e.g., 

rupture of a chlorine cylinder). Such 

conditions could occur during an emergency in 

a nuclear facility. 

Some of these non-radiological hazards that 

may affect the selection of a respiratory 

protection method are the existence of an 

explosive gas mixture, oxygen deficiency, 

high ambient temperature, low ambient 

temperature and low atmospheric pressure. 

The concurrent use of other safety equipment 

can also affect the selection. Safety glasses or 

goggles, a hard hat, hearing protection, 

communications equipment, and protective 

clothing can all affect the choice of respiratory 

protection method. Physical work locations 

may contain narrow passageways, ladders, or 

scaffolding that may dictate a less protective 

respirator to increase mobility and decrease 

chances of an industrial accident or injury. 

All of these potential hazards need to be 

considered when selecting a respiratory 

protection method. 

6.10.1 Physical Stresses 

Some physical discomfort associated with 

respirator use is unavoidable, no matter how 

much effort goes into product selection, 

materials of construction and fit testing. A few 

specific sources of discomfort (e.g., over

tightened head harness, or hair caught between 

straps and buckles) can be overcome by

NUREG/CR-0041, Revision I 96
effective training. Other sources of discomfort 

will always be present: inhaling or exhaling 

against pressure, an itching nose, or 

perspiration in the eyes. Even more discomfort 

is experienced by those suffering from 

allergies or a cold, dental aches, and facial 

skin conditions. 

It is common that full protective clothing 

(PCs) is required when respirators are used. 

Air-purifying respirators, especially, used in 

conjunction with PCs, greatly reduce the 

evaporative cooling process and contribute 

greatly to heat stress. This, in turn, can impact 

a worker's efficiency, thereby increasing work 

time and radiation dose. 

Supplied-air hoods, if used properly, are 

especially useful in mitigating heat stress. 

With the inner shroud (front and back) tucked 

inside the PCs, the exhausted air is directed 

down over the worker's torso. This allows 

evaporative cooling to take place over a major 

portion of the body, and keeps core body 

temperature with in acceptable limits. 

Continuous-flow facepiece respirators are not 

nearly as effective at cooling the wearer as are 

air-fed hoods. Since only the face is cooled, 

core body temperature can rise to dangerous 

levels while the person's temperature sensors 

(located principally on the face) are not 

providing a warning. 

Certain facepiece materials (e.g., silicone) 

tend to be more comfortable to wear for 

extended periods of time. Some facilities have 

instituted worker comfort assessments during 

the fit-testing process. The additional physical 

stresses associated with respirator use are the 

primary reason that respirator wearers are 

required to pass an initial medical screening 

and a periodic re-screening.

6.10.2 Increased Breathing Resistance 

While wearing negative-pressure, air

purifying respirators, inhalation resistance is 

attributable to the air-purifying element and 

the flow channels within the facepiece itself. 

As dirt builds up on the filter, breathing 

resistance increases. This resistance can range 

from 20 mm water pressure for the highest 

efficiency particulate filters, to about 50 mm 

water pressure for chin-mounted adsorber 

canisters (e.g., a "radioiodine" canister) over 

their useful service lives. Even at the 

minimum values, this additional resistance 

during the time of use can become a 

significant burden to the wearer. Since we 

inhale by contracting our intercostal and 

diaphragm muscles, these muscles fatigue 

faster as the inhalation resistance increases. 

The use of positive-pressure respirators 

(airline-supplied or air-purifying) might 

mitigate this problem, but the different stresses 

imposed by these devices would need to be 

evaluated. For instance, many inexperienced 

wearers of pressure-demand, airline-supplied 

devices or pressure-demand SCBA become 

apprehensive when they realize that exhalation 

is more difficult in these devices. 

Occasionally, they will remove the device and 

report that the exhalation valve is defective. 

This is most often observed when a heavy 

work rate is involved. The best solution to this 

problem is to point out this operating 

characteristic of pressure-demand devices 

during hands-on training. For air-purifying 

devices, the amount of time spent in 

respirators should be limited, air-purifying 

elements should be changed when increased 

breathing resistance is noticed, and lighter 

weight non-sorbent filters should be used 

whenever possible.

NUREG/CR-0041, Revision I 97
6.10.3 Increased Dead-Air Volume 

When an individual inhales, the air that 

initially reaches the alveolar region of the lung 

is the oxygen-depleted air that remains in the 

wearer's upper airways (nose, trachea, 

bronchi, etc.) from the previous exhalation. It 

is the newly inspired air that follows this 

"dead air" that is the primary source of 

oxygen. If a respirator is worn, an additional 

volume of oxygen-depleted air from the 

previous exhalation remains inside the 

facepiece. This respirator dead-air volume, 

added to the anatomic dead-air volume, 

requires the wearer to inhale both volumes of 

0 2-depleted air before any oxygen-rich air 

enters the lungs. The wearer of a negative

pressure respirator, then, must breathe more 

deeply and/or more frequently to provide the 

same amount of oxygen to his lungs. This 

increased depth and frequency of breathing 

when a negative-pressure respirator is donned 

is often misinterpreted as an anxiety response 

when in fact, it is physiological. 

Example

No Respirator Worn 

Anatomic dead air volume 

Required fresh air volume 

Total Inhaled Volume

150 cc 

350 cc 

500 cc

Wearing a Negative-Pressure Full Facepiece 

Anatomic dead air volume 150 cc 

Facepiece dead air volume 150 cc 

Necessary fresh air volume 350 cc 

Total Inhaled Volume 650 cc 

This 30% increase in air volume necessary per 

inhalation adds to the breathing effort required 

by the wearer, and can lead to early fatigue. 

Adding dead air volume to an individual by 

use of a respirator also increases the 

temperature of the inhaled gas and increases 

the partial pressure of carbon dioxide in the 

lungs. Since our rate and depth of respiration 

is determined, in large part, by the level of

CO 2 in our blood, these elevated levels may 

lead to mild hyperventilation. 

In situations where stress and fatigue caused 

by a respirator's dead air volume become a 

significant factor, powered air-purifying 

respirators and continuous-flow airline 

respirators are effective in keeping the 

facepiece full of oxygen-rich air. If use of 

these devices is not feasible, the increased 

physiological stress caused by negative

pressure respirators should be considered in 

establishing maximum work times or work

rest cycles. 

6.10.4 Additional Weight and Size 

SCBA can weigh as much as 35 pounds with a 

fully charged air cylinder. This weight is 

usually well distributed and held close to the 

user's body, and the back frame and shoulder 

straps are designed to be as comfortable as 

possible. This weight, however, exerts stresses 

on wearers that should be taken into account 

during medical screening and training. 

Most full-facepiece respirators weigh only I to 

3 pounds, which may seem insignificant. If the 

majority of the weight is in a large chin

mounted canister extending well out from the 

face, however, fatigue can result in muscles in 

the neck and upper back. This might lead the 

RPA to select facepieces that include cheek

mounted rather than chin-mounted filters, at 

least for some applications. 

Respiratory protection equipment unnaturally 

enlarges a worker's profile, necessitating 

caution when climbing or walking through 

tight spaces, looking through viewing ports, or 

handling bulky equipment. Balance is affected 

as well, and even simple tasks sometimes 

require extra concentration. Many normal 

physical activities need to be altered to 

accommodate the new profile and can result in 

strained muscles, additional overall stress, and 

accelerated fatigue. When unsuccessful 

maneuvers result in bumping into objects, or

NUREG/CR-0041, Revision 1 98
facepiece dislodgment, damage to the 

respirator or physical injury to the wearer can 

result. 

These respirator weight- and size-related 

problems can be mitigated to some extent by 

selecting the lightest-weight and smallest

profile model or type of respirator available 

that will provide the necessary level of 

protection. An adequate training program will 

give respirator wearers experience using the 

devices in various environments. Consider 

these factors when establishing maximum 

work times or work-rest cycles. 

6.10.5 Limited Mobility 

Respiratory protection devices that require an 

umbilical cord (e.g., airline respirators) 

present obvious limitations to mobility of the 

wearer. Gaining access to a work area 

sometimes requires as much effort as 

performing the actual task. Consider using 

airline hose reels or festooning systems to 

keep the hoses tended and out of the way. The 

NIOSH approval for all airline-supplied 

respirators specifies a maximum air-hose 

length of 300 feet. It also requires the use of a 

belt, to which the regulator and supply hose 

are attached. This belt takes the strain of the 

air hose off the facepiece or hood. 

One strategy for reducing the effect of these 

air hose-related problems is to provide a 

breathing air source as close as possible to the 

work area, and use of a combination air

purifying/airline-supplied respirator system. 

Another option is to provide a second 

individual as air-hose tender to manage the 

hose and keep it from tangling. Selection of a 

different type of respirator, such as a powered 

air-purifying device, will eliminate the 

umbilical problem altogether as long as it will 

adequately address the airborne contaminant 

present in the area.

6.10.6 Psychological Distress 

Many workers experience simple anxiety 

when wearing a respirator. This may be partly 

caused by the additional dead-air volume 

added by the negative-pressure facepiece, by 

mild claustrophobia, or by concern over the 

work environment. Whatever the reasons, it is 

very common even among experienced 

respirator wearers for the pulse to quicken and 

the breathing rate to increase. Whether slight 

or severe, respirator use increases the 

psychological stress on the wearer. 

The best defense against respirator-induced 

psychological distress is to maximize worker 

familiarity with the respiratory equipment and 

with the work environment. Training should 

illustrate how the devices operate; what they 

can and cannot do as far as protecting the 

wearer; how they should be donned, doffed, 

and worn; how they are cleaned, sanitized, 

maintained and stored. This should give the 

worker confidence in the equipment's 

capabilities and in the care taken by respirator 

program personnel to ensure that each 

respirator issued is clean and working 

properly. Finally, the respirator fit-testing 

process, if performed and explained properly, 

should clearly show the worker that the 

respirator is an effective protective device if 

worn correctly. 

6.11 High-Temperature Work Areas 

(Heat Stress) 

Heat stress is a complex interaction among 

environmental factors, clothing and protective 

devices used, and work demands as they 

impact on work performance, safety, and 

health. The most obvious manifestation of 

physiological strain is sweating, which is 

accompanied by increases in heart rate and 

body temperature. As exposures to heat stress 

become more significant and the physiological 

strain increased, the ability to perform physical 

and mental work diminishes. A heat-stressed 

person cannot work as hard as, and is more

NUREG/CR-0041, Revision I 99
likely to make mistakes than, a non heat

stressed worker. As physical and mental 

performance decrease, the likelihood of an 

accident increases. Ultimately, if the heat 

exposure continues unabated and the normal 

physiological responses to heat stress are 

insufficient to protect the worker, a 

heat-related disorder will occur. 

6.11.1 Heat-Related Disorders 

The five most commonly described 

heat-related disorders are: 

* Rash; 

"* Cramps; 

"* Syncope; 

"* Exhaustion; and 

"* Stroke. 

Heat rash is caused by obstruction of the 

sweat glands brought on by chronically wet 

skin. The symptoms are itchy skin with small 

red spots and an unusual sensitivity to radiant 

heat. To treat heat rash, allow intermittent 

relief from the hot environment. Heat rash can 

be prevented by keeping the skin clean, and 

periodically allowing the skin to dry. 

Heat cramps are caused by profuse sweating 

and hard work. They are associated with an 

excessive loss of salts and are manifested as 

painful muscle cramps in legs, arms or 

abdomen. The cramps may occur during or 

after exertion. Massage cramping muscles to 

obtain relief, and give water orally. Prevent 

heat cramps by supplementing electrolyte 

intake by using sport drinks or some other 

method. 

Heat syncope (pronounced "sin-ka-pee") is 

brought on when a worker maintains one work 

posture (e.g., standing or squatting) for too 

long a time. This allows blood to pool in the 

legs, away from the head. Standing or sitting 

up quickly will cause a dizzy feeling or a brief 

fainting spell of less than 30 seconds duration. 

Treat heat syncope by allowing the worker to 

rest lying down. Administer water or other

suitable fluid orally. To prevent or reduce heat 

syncope, instruct workers to flex their leg 

muscles several times before moving from a 

stationary position, and to stand or sit up 

slowly. 

Heat exhaustion is often precipitated by heavy 

sweating, which causes dehydration. If a 

person is already dehydrated due to an illness 

(e.g., vomiting or diarrhea), the onset of heat 

exhaustion will be hastened. The symptoms 

are a general feeling of fatigue or weakness, 

uncoordinated actions, headache, thirst, and 

weak pulse. The treatment is simply to rest in 

a cool environment. Prevent heat exhaustion 

by drinking water or other suitable fluids 

frequently, and by adding salt to food. 

Heat stroke is a life-threatening condition. It 

may be brought on by a pre-existing illness 

(e.g., fever or flu), an abnormal intolerance to 

heat stress, excessive exposure to heat stress, 

or by drug or alcohol abuse. A person in heat 

stroke will have difficulty recognizing 

surroundings or people and may exhibit 

irrational or unexpected behavior. The skin 

will be dry. Convulsions or unconsciousness 

for periods greater than 30 seconds may also 

occur. Treat heat stroke by immediately and 

aggressively lowering the person's body 

temperature. This can be accomplished by 

wetting the skin and clothing and increasing 

the airflow by using fans, ventilation trunks, or 

by manual fanning. Ice packs may also be 

used if available. Transport the victim 

immediately to an emergency medical facility, 

even if the victim reports feeling better. 

Prevent heat stroke by training personnel to 

recognize the symptoms of heat-related 

disorders in themselves and in others, and by 

allowing the workers to participate in the 

determination of heat stress exposures. 

Maintaining a healthy life-style will also 

reduce the likelihood of heat stroke. 

Lightly salting food at mealtimes should be 

encouraged during training as both treatment 

for and prevention of some heat disorders. 

Those individuals on salt-restricted diets

NUREG/CR-0041, Revision I 100
should consult their personal physicians 

regarding the advisability of exposure to heat 

stress and the supplementing of salt intake. 

Salt tablets, however, should never be used. 

6.11.2 Evaluation of Heat Stress 

Before countermeasures can be selected, the 

heat stress should be evaluated. The evaluation 

process should measure or estimate three 

factors. 

"* Environmental heat sources and factors; 

"* Metabolic heat (generated internally while 

working); and 

"* Clothing requirements. 

Environmental heat sources include 

convection, which is reflected in air 

temperature and air movement, and radiant 

heat, which depends on the temperatures of 

surrounding walls, equipment and other 

surfaces. An important environmental factor is 

air humidity, which affects the body's ability 

to cool itself by evaporation of perspiration. 

Air temperature alone is not a very good 

predictor of heat stress potential. 

An empirical index of environmental heat that 

was developed to account for these 

environmental factors is the wet bulb globe 

temperature (WBGT) index. The wet bulb 

temperature (a water-dampened wick 

surrounds the thermometer bulb) is always 

lower than air temperature, but it will increase 

with increasing levels of humidity. The globe 

temperature (a thermometer inside a hollow, 

black-painted globe) depends on air motion, 

air temperature, and the temperature of the 

solid surroundings (radiant heat). It rises and 

falls with the degree of convection and radiant 

heat that may be present. In locations away 

from direct sunlight, the "indoor" WBGT is 

the sum of 70% of the wet bulb temperature 

and 30% of the globe temperature. 

WBGTindoor = 

0.7(wet bulb temp) + 0.3(globe temp.)

For work in direct sunlight, the "outdoor" 

WBGT is used. This is the sum of 10% of the 

dry bulb air temperature (which accounts for 

solar heating), 20% of the globe temperature, 

and 70% of the wet bulb temperature. 

WBGTouldoor= 0.7 (wet bulb temp) 

+ 0.2 (globe temp) + 0.1 (dry air temp) 

Because of the heavy weighing on wet bulb 

temperature, the WBGT value is almost 

always much less than the dry bulb air 

temperature. 

Metabolic heat, or body heat generated by 

work demands, is most easily estimated from 

tables of typical activities. Tables are provided 

for estimating work demands in terms of 

energy expenditure rate (kilocalories per hour 

or kcal/h). Light work, such as instrument 

repair or supervision, ranges from 100 to 

200 kcal/h. Moderate work, typical of most 

maintenance tasks, ranges from 200 to 

325 kcal/h. Heavy work, requiring a great deal 

of physical effort (e.g., continuous shoveling, 

mopping, installing shielding) ranges from 

325 to 450 kcal/h. 

Also important in gauging metabolic heat is 

the anticipated work-rest regimen. It should be 

estimated what percent of a worker's time in 

the potential heat stress area will actually be 

spent working, and what percent will be spent 

resting or at least not working (and not 

generating additional metabolic heat). 

Clothing requirements, the third factor used to 

determine the level of heat stress, mostly 

affect the body's ability to cool by sweat 

evaporation. Multiple layers of clothing or 

vapor-barrier clothing significantly reduce the 

ability to evaporate perspiration, and therefore 

cause greater physiological strain. 

Adjustments should be made to the WBGT 

index when clothing other than a single layer 

of light summer-type clothing is worn (e.g., in 

an uncontaminated area). When one layer of 

anti-contamination clothing is worn add 2 'C

101 NUREG/CR-0041, Revision 1
to the WBGT reading. Add 4 °C when 2 layers 

of PCs are worn. 

If vapor-barrier clothing is worn (full plastic 

PCs), the WBGT index is not an appropriate 

estimator of heat stress, since evaporative 

cooling has been eliminated for workers 

wearing this type of garb. In this case, use 

only the air temperature and the globe 

temperature in the following relationship. 

Adjusted dry bulb temp. 

0.5 (globe temp.) + 0.5 (air temp)

The environmental heat measurement (WBGT 

or Adjusted Dry Bulb temperature, as 

appropriate), the estimate of metabolic heat 

(e.g., moderate work, 50% work, 50% rest), 

and protective clothing requirements are then 

all factored together to determine whether or 

not a potential for heat stress exists. Several 

examples of how this is done are given below. 

The environmental heat measurement (WBGT 

or Adjusted Dry Bulb temperature, as 

appropriate), the estimate of metabolic heat 

(e.g., light work : 100-200 kcal/h, heavy work 

325-450 kcal/h), and protective clothing 

requirements are then all factored together to

Figure 6-2. NIOSH-recommended exposure limit (REL) for heat stress.

NUREG/CR-0041, Revision 1 102
determine whether or not a potential for heat 

stress exists. Several examples of how this is 

done are given below. When interpreting 

Figure 6-2, if the coordinate of the measured 

environmental heat load and the estimated 

metabolic heat production occurs above the 

ceiling limit curve (C), work should not be 

performed until action is taken to reduce one 

or both of the heat factors. If the coordinate 

falls between two of the curves (e.g., between 

45 min/h and 60 min/h) then the work-rest 

regimen indicated by the upper (more 

restrictive) curve should be followed. 

Examples 

Situation 1. The WBGT index for a work area 

has been measured at 30 °C. You estimate that 

the workers will be performing work in the 

high end of the "moderate" range. Since this is 

a contaminated area, they will be wearing one 

set of PCs. 

Assessment 1. Since I set of PCs will be 

worn, 2 °C should be added to the WBGT 

reading, making this adjusted value 32 'C. On 

Figure 6-2, draw a horizontal line at the 32 *C 

point. Since the work to be performed will be 

at the high end of the moderate range, draw a 

vertical line at about 325 kcal/h. These two 

lines intersect below the 15 min/h work-rest 

curve but above the 30 min/h curve. Therefore 

the work can take place beginning with 15 

minutes of work followed by 45 minutes of 

rest. These workers, however, will be in a 

potential heat stress situation, and appropriate 

engineering controls, and/or protective 

countermeasures should be considered. These 

are discussed below. As work progresses, the 

work-rest cycle can be adjusted based on how 

well or how poorly the workers react to the 

heat stress. 

Situation 2. The WBGT index for a work area 

has been measured at 260C. You estimate that 

the workers will be performing work in the 

middle of the moderate range. Since this is a

highly contaminated area, they will be wearing 

2 sets of PCs. 

Assessment 2. Since 2 sets of PCs will be 

worn, 4VC should be added to the WBGT 

reading, making this adjusted value 30 'C. On 

Figure 6-2, draw a horizontal line at the 300C 

point. Since the work to be performed will be 

in the center of the moderate range, draw a 

vertical line at about 265 kcal/h. Since these 

two lines intersect below the 30 min/h work

rest curve but above the 45 min/h, the work 

can take place beginning with 30 minutes of 

work followed by 30 minutes of rest each 

hour. These workers, however, will be in a 

potential heat stress situation, and appropriate 

engineering controls, and/or protective 

countermeasures should be considered as 

described below. As work progresses, the 

work-rest cycle can be adjusted based on how 

well or how poorly the workers react to the 

heat stress. (Note that in this situation, if the 

protective clothing requirements could be 

reduced to one set, the point on Figure 6-2 

where the environmental heat intersects with 

the metabolic heat would be below the 60 

min/h curve and the work situation would no 

longer involve heat stress.) 

Situation 3. The work to be accomplished 

must be performed in full plastic PCs. The 

WBGT index, therefore, does not apply. 

Instead the Adjusted Dry Bulb temperature 

should be used. This temperature is 41°C. You 

estimate that the workers will be performing 

work at the low end of the moderate range. 

Assessment 3. On Figure 6-2, draw a 

horizontal line at the 41'C point. Since the 

work to be performed will be at the low end of 

the moderate range, draw a vertical line at 

about 210 kcal/h. Since these two lines 

intersect above the ceiling limit curve, the 

work should not take place. Some combination 

of engineering controls, and/or protective 

countermeasures should be implemented 

before this work begins. These are discussed 

below.

103 NUREG/CR-0041, Revision I
6.11.3 Complicating Factors 

Physical condition. The WBGT heat stress 

index is designed for a "Standard Worker" 

weighing 154 pounds and having a body 

surface area of 19.4 ft2. What about the effects 

of heat stress on workers who are outside 

these standard parameters upon which 

Figure 6-2 is based? The overriding 

consideration in predicting a person's 

tolerance to heat stress is physical condition. 

Parameters such as body weight, sex, and 

personal habits have an effect only insofar as 

they impact overall physical fitness. The more 

physically fit a worker is, the better he/she will 

be able to tolerate a heat stressful situation. 

While there is no way to quantify these 

differences, some generalizations can be made 

which may be taken into account when work 

in high temperatures is required. 

Body fat. An overweight worker will generally 

have more of a problem in a heat stressful 

work environment than one who is of average 

weight. Carrying additional weight means that 

more energy must be expended to perform any 

given task. Thus, metabolic heat generation is 

greater. Also, the fatty layer of tissue acts as 

an insulator, making heat dissipation from 

muscles and other deeper-lying tissues more 

difficult. In addition, the body surface area-to

weight ratio (ft2 to pounds) becomes less 

favorable for heat dissipation. That is, the 

overweight worker's body has less surface 

area per pound of body weight, and the body's 

primary heat removal method (through the 

skin) is less effective. 

Age. There is some information that workers 

over 40 years of age will perform less well in 

a high temperature situation than younger 

workers. 

Gender. There appears to be no difference in 

tolerance to heat stress between women and 

men of the same physical size. This tolerance 

does not seem to vary over the menstrual 

cycle.

Alcohol use. The use of alcoholic beverages 

before (or during) work in the heat should not 

be permitted. Alcohol use is clearly associated 

with heat stroke, and increases the risk of 

other heat-related illnesses. It also reduces a 

worker's tolerance to work in high 

temperatures. 

Drug use. Many drugs, both prescription and 

otherwise, can negatively affect heat tolerance. 

A worker who is taking medication should be 

under the supervision of a physician who 

understands the potential ramifications of the 

drugs on heat tolerance. At the very least, 

workers taking prescription medication should 

be required to work into heat exposure 

situation gradually (i.e., short exposures) until 

the limits of their capacity to work in a high

temperature environment are established. 

Generally speaking, the drugs of most concern 

are those which affect the central nervous 

system (tranquilizers, anti-depressants, 

stimulants), cardiovascular reserve, and body 

hydration (diuretics). 

Individual variation. Different individuals 

exhibit a wide variation in responses to heat 

environments. Sometimes the same individual 

may perform well in some heat-stressful 

situation and poorly in others. About half of 

these situations can be related to differences in 

body size and physical fitness. The reasons for 

the rest are not understood. 

Acclimatization. When workers are first 

exposed to a hot work environment, they will 

usually show signs of distress and discomfort. 

They will also develop increased deep body 

temperatures and heart rates. They may 

complain of headaches, giddiness or nausea. 

Some may also faint on first exposure. On 

repeated exposure to high temperatures there 

is a marked adaptation, resulting primarily 

from the body's increased sweating efficiency. 

This means that the acclimatized worker will 

start sweating sooner, produce larger 

quantities of perspiration, and the electrolyte 

concentration in the sweat will be reduced 

(less loss of electrolytes). After five daily

NUREG/CR-0041, Revision I 104
exposures to high temperature of 100 or 

more minutes per day, a worker will be 

approximately 80% acclimatized. (The 

100 minutes need not be one single exposure.) 

Full acclimatization will be achieved in 

approximately ten days. Little of the 

acclimatization will be lost during 1 or 2 days 

off. Absence of heat exposure for a week or 

more, however, results in significant loss of 

the beneficial adaptation. After a one-week 

absence, heat acclimatization can be regained 

in 2-3 days upon return to the heat work 

environment. A worker absent due to illness 

will probably need I day of re-acclimatization 

for each day absent. A physically fit worker 

will generally acclimatize faster and maintain 

it better than a worker who is in poorer 

condition. This means that it would probably 

be better to assign one work crew to a high

temperature job of long duration, and let them 

work the job until completion. Changing work 

crews daily would inhibit acclimatization of 

all workers and increase the overall heat stress 

to all workers. 

Respirator use. Another question involves the 

use of respirators in a high-temperature 

environment. The fact is that there is no 

convincing evidence that filter respirator use 

increases the heat stress on a worker. A 

respirator will, however, add to the workers 

subjective strain, and due to increased 

discomfort may shorten the worker's tolerance 

time in the work area. If the use of respiratory 

protective devices is required in a heat 

stressful work situation, some less stressful 

device should be chosen if possible. The 

advantages and disadvantages of different 

types of respiratory protection devices are 

discussed elsewhere in this Manual. 

6.11.4 Reducing Heat Stress 

Four methods of heat stress reduction are 

discussed here. They are: 

"* Engineering controls; 

"* Personnel protective equipment (PPE);

"* Administrative controls; and 

"* General countermeasures. 

Engineering Controls 

Reduction of work load and/or work rate will 

reduce the metabolic heat production and 

therefore, decrease worker stress. This 

probably has the greatest potential for stress 

reduction. Any mechanical assistance that can 

reduce workload should be considered. For 

instance, the use of slings and chain falls to 

raise a large valve bonnet, or the use of 

pneumatic drivers to tighten nuts, will reduce 

the physical work required by workers. 

Reduction of air temperature and humidity are 

next in order of effectiveness. Dilution 

ventilation and air conditioning have been 

successfully applied to heat stress problems in 

the nuclear industry. 

Increasing air velocity is the least effective of 

the engineering controls. Unless the 

temperature and/or the humidity of the air are 

also reduced, very little actual lessening of 

heat stress will be realized. Another 

consideration is that the increased airflow 

might cause surface contamination to become 

airborne, potentially increasing internal dose 

and possibly requiring the use of respirators. 

In any event, the heat stress problem could be 

greatly complicated by increasing airflow in a 

highly contaminated area. 

Reduction of radiant heat can be effective if 

radiant heat is a contributor to the problem. 

Simple heat shields can be erected for short

duration jobs. Insulation of radiant heat 

sources can be considered for the long term. 

Surface emissivity is frequently overlooked. 

The shinier a surface, the lower its emissivity 

and therefore, the less able it is to radiate heat 

to nearby workers. This is the reason that 

"mirror" insulation is used in some 

applications.

105 NUREG/CR-0041, Revision 1
Personal Protection 

Personal protection in the form of personal 

cooling (and possibly reflective clothing) is 

recommended for conditions when: 

"* The minimum expected safe time 

exposure is less than 60 minutes; 

"• The WBGT index exceeds the ceiling 

limit, or 

"* Vapor barrier clothing is used by exposed 

personnel. 

Personal protective equipment can be grouped 

into four categories. 

"* Ice vests; 

"* Air cooled systems; 

"* Circulating liquid systems; and 

"* Vortex air coolers. 

The first three are far more effective overall 

than the fourth. 

Ice vests permit a great deal of mobility, with 

typical service times on the order of one to 

two hours. While these require some 

additional personnel support and the 

availability of a freezer, they have proven to 

be well worth the effort. The incidence of 

heat-related illness can be expected to 

decrease, and increased worker stay times 

enhance productivity. Once the ice in the vest 

is substantially melted, the differential 

temperature between the vest and the wearer's 

body decreases, quickly reducing its 

effectiveness. At this point, the vest becomes a 

liability due to its weight, absence of cooling 

effect, limiting the evaporation of perspiration 

from the wearer's torso, and acting as an 

insulator to retain metabolic heat. 

Supplied air hoods, if used properly, are 

especially useful in mitigating heat stress. 

With the inner shroud (front and back) tucked 

inside the PCs, the exhausted air is directed 

down over the worker's torso. This flow of dry 

air promotes evaporation of perspiration over 

a major portion of the body, and the 

temperature drop caused by depressurization 

of the air provides additional body cooling,

keeping core body temperature within 

acceptable limits. 

Continuous-flow facepiece respirators are not 

nearly as effective as air-fed hoods. In fact, 

since only the face is cooled, deep body 

temperature can rise to dangerous levels while 

the person's temperature sensors (located 

principally on the face) are saying that 

everything is fine. 

Circulating liquid systems are similar to ice 

vests, in that they are worn as a vest or suit. A 

liquid flows through capillary tubes built into 

the garment, absorbing heat. The liquid is 

usually cooled by equipment near the work 

area, requiring the worker to be connected by 

umbilical to the cooling system for the 

garment to work. These garments weigh a 

good deal less than a fully loaded ice vest. 

Vortex air coolers take advantage of the fact 

that air temperature drops when it is 

depressurized. Air is depressurized in a vortex 

cooler, which can be compared to a tube-and

shell heat exchanger. Air being supplied to the 

wearer passes through one or more tubes in 

the belt-mounted heat exchanger while some 

air is allowed to be depressurized around the 

outside of these breathing-air tubes, thus 

cooling the air that will be breathed. The air 

exhausted from the vortex tubes might 

contribute to airborne contamination levels. 

Licensees are reminded that a respirator 

system must be NIOSH-certified with the 

vortex cooler. A vortex cooler should not be 

added into a system that is not NIOSH

approved to include the cooler. 

Administrative Controls 

Self-determination. Each worker may decide 

when he or she has reached a point where 

relief is needed from a high temperature work 

situation. The individual worker should 

understand that there are differences among 

workers for heat tolerance and that each 

individual should end an exposure at the first

NUREG/CR-0041, Revision 1 106
symptoms of weakness, fatigue, nausea, or 

other signs of heat-related disorders. This is a 

central tenet of managing heat stress and 

should be emphasized during training. 

Check time (CT) is a control that requires each 

worker to make an explicit decision to 

continue working rather than only an implicit 

decision to stop (self-determination). Its value 

is based on the heat stress conditions and is a 

minimum expected safe exposure time. At the 

check time, and at intervals afterward, the 

workers are asked (1) if they are experiencing 

any symptoms of heat disorders and (2) if they 

can continue. An explicit decision is thus 

requested. 

Recovery allowance and work/rest cycles are 

designed to allow sufficient recovery from 

previous heat stress exposures before a 

subsequent exposure is undertaken. Work/rest 

cycles are suggested for long-term exposures 

to heat stress in the NIOSH documentation as 

seen in Figure 6-2. If rest breaks are provided 

for in the work cycle, the WBGT action 

threshold can be increased. 

Scheduling hot work during a time of lower 

heat stress is a commonly recognized control 

method. Working hot jobs on back shifts when 

air temperatures are cooler, or scheduling the 

work to be accomplished in late fall through 

early spring are examples of this strategy. 

Clothing requirements can be reviewed and 

possibly reduced to lower the heat stress. 

This may require area or equipment 

decontamination or other efforts. NRC 

regulations place limits on doses to personnel. 

They do not specify maximum contamination 

levels or prohibit skin contamination. 

A buddy system provides for mutual 

observation and assistance in the event of a 

heat disorder. 

Personal monitoring means that physiological 

measurements may be taken to alert 

individuals to excessive physiological strain. 

Advice about maximum oral temperature and

heart rate, and for heart rate recovery, should 

be obtained from a physician or industrial 

hygienist. Equipment is commercially 

available that can monitor both body 

temperature and heart rate continuously, 

without interfering with the work. 

General Countermeasures 

Medical screening should be accomplished 

prior to first exposure and periodically 

thereafter for workers who will be exposed 

throughout the year. This could easily be 

incorporated into the periodic respirator 

medical screening, but the examining 

physician should be aware that the workers 

will be exposed to heat stress. This will allow 

medications and medical conditions that might 

not otherwise be of concern to be given 

special consideration due to the potential for 

exposure to heat stress. 

Training sufficient to provide exposed 

individuals with the knowledge required to 

deal effectively with heat stress should be 

provided prior to first heat stress exposure. 

Annual retraining is recommended. This can 

be accomplished during annual radiation 

worker re-qualification, in first aid classes, or 

during safety meetings. Adequate heat stress 

training requires only 30 minutes per year. The 

recommended training content includes: 

"* Sources of heat stress; 

"* Physiological responses; 

"* Recognition of and first aid for heat 

disorders; 

"* Engineering controls; 

"* Use of personnel protective equipment; 

"• Administrative controls; and 

"* General countermeasures. 

Fluid replacement is essential to restore the 

water lost by perspiration. Ideally, water is 

replaced frequently (e.g., 3-4 times per hour). 

In restricted areas 2 where eating and drinking 

- Referred to as radiologically controlled areas (RCAs) 

at most reactor facilities.

107 NUREG/CR-0041, Revision 1
may be prohibited by the license, workers 

should be encouraged to pre-hydrate (drink 

more than usual before the heat exposure), and 

then to drink additional water afterwards. The 

NRC does not prohibit workers from drinking 

inside the restricted area or RCA. Regulations 

place limits on TEDE and require that doses 

be kept ALARA. Licensees have successfully 

established programs that make potable water 

available in contaminated areas while keeping 

the likelihood of ingestion of radioactive 

material to a minimum. Consider the use of 

squeeze bottles or single-use paper cups. A 

weight loss of more than 0.2 kg (0.44 pounds) 

per day is probably indicative of dehydration. 

A typical diet probably contains all the salts 

and other nutrients that are necessary to cope 

successfully with heat stress, but lightly 

salting food at mealtimes can be encouraged 

during training as both treatment for and 

prevention of some heat disorders. Those 

individuals on salt-restricted diets should 

consult their personal physicians regarding the 

advisability of exposure to heat stress and 

supplementing salt intake. Salt tablets should 

never be used. Large doses of salt will absorb 

and hold water, preventing it from getting to 

the body tissues where it is needed, and will 

also irritate the stomach lining. There are, 

however, a number of specially developed 

commercial drinks (e.g., sports drinks) that 

contain various electrolytes and nutrients. 

During exposures to heat stress, it is the water 

in these drinks that is most important. Because 

these drinks are flavored, they may be more 

acceptable to the work force, thus encouraging 

water replacement. Other flavored drinks (e.g., 

dilute iced tea or lemonade) can also be used 

to promote water replacement by making the 

drink more palatable.

6.12 Toxic and Nuisance Atmospheres 

6.12.1 Common Toxic Gases and Vapors at 

Nuclear Facilities 

Some common toxic materials that could 

present personnel hazards at nuclear facilities 

are discussed below. In particular, the 

physiological effect of brief exposure to high 

concentrations will be discussed, which relates 

to the IDLH concentrations. The IDLH values 

have been taken from the NIOSH Pocket 

Guide to Chemical Hazards (DHHS-NIOSH 

Publication 97-140, June 1997). Bulk releases 

of these gases mix slowly with air, especially 

if their specific gravity is much different than 

that of air, which is I. This is especially 

hazardous in low-lying areas. 

Chlorine is an extremely toxic gas. Adverse 

symptoms can occur after several hours of 

unprotected exposure, even at concentrations 

of 1 ppm. Chlorine has a sharp, penetrating 

odor above 3-5 ppm. Low concentrations 

cause general irritation of the respiratory 

system, whereas higher concentrations 

(50 ppm for 20 minutes, or 1000 ppm for 

1 minute) can be fatal. The IDLH 

concentration is 10 ppm. Chlorine has a 

specific gravity of 2.49. Chlorine is commonly 

used at nuclear facilities to inhibit marine 

growth in plant cooling systems during plant 

operations. Several events involving chlorine 

releases are described in IE Circular 80-03. 

Guidance for providing protection of power 

plant control room operators is provided in 

NRC Regulatory Guide 1.95. 

Hydrogen fluoride (HF) is a highly toxic 

liquid (hydrofluoric acid) or gas with a strong, 

irritating odor. Its sharp, penetrating odor 

ordinarily prevents voluntary inhalation of 

toxic quantities. Contact with skin causes very 

painful and medically serious burns. Liquid 

contact with eyes can cause immediate 

blindness. Exposure to high concentrations 

will result in pulmonary edema, and burns of 

the skin, eyes, and upper respiratory tract. 

Exposure to low concentrations of HF gas will

NUREG/CR-0041, Revision I 108
result in irritation of the eyes, nose, throat, and 

the upper respiratory tract, and it will cause 

nasal congestion and bronchitis. With an 

IDLH of 30 ppm (0.003% by volume), HF is a 

highly dangerous substance. HF gas has a 

specific gravity of 0.69. It is noncombustible 

but difficult to contain as it corrodes most 

substances except lead, wax, polyethylene, 

and platinum. It may be present in uranium 

hexafluoride (UF 6) processes. 

Hydrogen sulfide (H2S) may be a byproduct 

from the decomposition of organic material. It 

is a colorless gas with a strong and easily 

detectable odor of rotten eggs. However, H2S 

will quickly deaden the olfactory nerves. 

Exposure to high concentrations can quickly 

result in death due to respiratory paralysis 

(apnea). Other physiologic effects are coma, 

convulsions, irritation of the eyes with 

conjunctivitis and pain, lacrimation, 

photophobia, corneal vesiculation, irritation of 

the respiratory system, dizziness, headaches, 

fatigue, insomnia, and gastrointestinal effects. 

Hydrogen sulfide has an IDLH concentration 

of 100 ppm (0.1% by volume), and because of 

its pronounced and rapid physiologic effects in 

high concentrations, potential exposure should 

be given careful consideration. H2S may be 

created due to decaying marine growth in 

circulating cooling systems when these 

systems are shut down and drained for 

periodic inspections. H2S is also flammable. It 

is heavier than air (specific gravity of 1.19), 

and may travel a considerable distance to an 

ignition source, and flash back. It is 

dangerously reactive with fuming or strong 

nitric acid and other oxidizers. 

Uranium hexaflouride (UF6) is a highly 

corrosive vapor with properties similar to HF, 

and is considered the most toxic of the 

common uranium compounds, excluding the 

radioactive aspects. If released to the 

atmosphere, UF 6 combines with moisture in 

the air and produces HF. There has not been an 

IDLH level uniquely established for UF 6, but 

due to its close relationship with HF, which 

may also be present, protective measures taken

for HF should be sufficient for UF 6. This, of 

course, excludes the radioactive aspects that 

may be present with the UF 6. UF6 is a liquid at 

room temperature, and has a dense vapor. 

Other uranium compounds, including such as 

U0 2F2 , UCI4, U0 2(NO 3)2 6H 20, U30 8, UF 4, 

and UO 2 present less of a hazard than UF 6. As 

a group, soluble uranium and its soluble 

compounds present a danger of kidney 

damage when inhaled or ingested. Generically, 

uranium and its compounds (both soluble and 

insoluble) have been assigned and IDLH level 

of 10 milligrams per cubic meter of air 

(rmg/in 3 ). An intake of 300 mg of soluble 

uranium is considered to be lethal within 

30 days to 50% of those who receive that 

intake (LD 5 0,,30). 

Although airborne uranium compounds 

present an internal radiation problem, the 

limits of intake of soluble uranium compounds 

are based on chemical toxicity rather than 

radioactivity. A soluble uranium compound 

deposited in the lung transfers rapidly to the 

bloodstream. Although a large fraction is 

quickly excreted, a sufficient amount may 

remain in the kidneys to cause chemical 

damage. On the other hand, an insoluble 

uranium compound may remain in the lung 

indefinitely. 

Exposure to high concentrations of uranium 

compounds can result in conjunctivitis, 

shortness of breath, coughing, chest rales, 

nausea, vomiting, skin bums, red blood cell 

disorders, casts in urine, albuminuria, high 

blood urea nitrogen, and lymphatic cancer. 

Solvents and solvent-containing materials. 

There are numerous petroleum and chlorinated 

solvents that may be present in a nuclear 

facility, either as a pure solvent, or as part of a 

paint and coating formulation. Unless properly 

stored and controlled, these may present a fire 

and toxicity hazard. Many of the organic 

solvents are flammable and their vapors are 

also explosive.

109 NUREG/CR-0041, Revision I
6.12.2 Inert Gases 

Hydrogen (H,) is a colorless and odorless gas. 

It may be present in the pure gaseous form as 

a coolant for electrical generators, in reactor 

coolant systems, waste gas treatment systems 

for both PWR and BWR, or as a byproduct of 

other processes such as the treatment of 

makeup water (mixing strong bases and acids). 

Hydrogen does not have an IDLH limit or 

concentration and is considered a simple 

asphyxiant. A high concentration will only 

result in an oxygen-deficient atmosphere being 

created through displacement of the ambient 

oxygen. Hydrogen has a very low specific 

gravity of 0.07. It has no other physiologic 

effect. However, in combination with 02, H2 is 

highly explosive.3 

Nitrogen (NZ), Argon (Ar), and Helium (He), 

three inert gases, have been lumped together 

as they are frequently used as inerting agents 

in enclosed spaces. Their only physiologic 

effect is asphyxiation; therefore, oxygen 

deficiency is the major consideration. The 

specific gravity of each is: 

Nitrogen 0.97 

Argon 1.38 

Helium 0.14 

Therefore, high-concentration pockets of 

argon would be found in low areas whereas 

helium would be found near the ceiling. 

Carbon dioxide (C02), a colorless and 

odorless gas, will be most commonly present 

in fire suppression systems. It has an IDLH 

concentration of 50,000 ppm (5% by volume). 

It is a relatively nontoxic gas and the 

physiologic effect at lower concentrations is to 

increase the breathing rate. The response to 

increased carbon dioxide concentration varies 

with the individual, but 5% to 10% usually 

3 See the following for descriptions of events related to 

hydrogen gas detonations at nuclear reactor facilties: IE 

Bulletin 78-03; IE Information Notice 82-28; and IE 

Information Notice 86-43. A complete list of respirator

related NRC bulletins, circulars and notices is included 

in the front of this Manual.

causes a headache in addition to increased 

breathing rate. As used in fire suppression 

systems, the major hazard will be the 

possibility of an oxygen-deficient atmosphere 

being suddenly created. Carbon dioxide tends 

to stay in low-lying areas, since its specific 

gravity is 1.52. 

From 1975 through 1999, there were a total of 

63 deaths and 89 injuries resulting from 

accidents involving the discharge of CO 2 fire 

suppression systems. Four are summarized 

below. 

1. In September, 1985, an inadvertent 

initiation of the carbon dioxide fire 

suppression system at a nuclear power reactor 

caused the release of approximately 10 tons of 

cardox (liquid carbon dioxide under pressure) 

into one of the four diesel generator fuel oil 

storage tank rooms. The affected room 

pressurized and carbon dioxide leaked into 

adjacent areas where several workers were 

overcome. Twenty-three people were 

transported to nearby hospitals with one 

individual listed in serious condition upon 

arrival. The plant was evacuated, and search 

and rescue teams reported some difficulty in 

accounting for all construction personnel 

during the search to ensure all persons had 

been evacuated. There were no fatalities. 

2. On January 15, 1999, an inadvertent 

discharge of the CO 2 fire suppression system 

occurred in the cable spreading room of a 

nuclear power plant. The cable spreading 

room is located in the control building directly 

below the control room. The actuation was 

caused when a non-licensed plant equipment 

operator trainee in the service building blew 

dust off a printed circuit board located in the 

cable spreading room CO 2 control panel 

located in the service building. There were no 

plant personnel in the cable spreading room at 

the time of the discharge. Shortly after the 

discharge, CO 2 was found to have migrated 

down into the switchgear rooms located 

directly below the cable spreading room. 

Approximately 37 minutes after initiation, the

NUREG/CR-0041, Revision I 110
licensee used a portable instrument to measure 

the concentration of CO 2 in one of the control 

building stairwells (which allows access to the 

control room, the cable spreading room and 

the switchgear rooms). The reading was off

scale high, indicating that the CO 2 

concentration was in excess of 50,000 parts 

per million (ppm). The current NRC 

Regulatory Guide 1.78 recommended toxicity 

limit for CO 2 is 10,000 ppm.4 On the basis of 

this indication, the licensee declared the area 

uninhabitable. Approximately 2 hours after the 

CO 2 discharge, operators aligned the control 

building purge system to remove CO 2 from the 

switchgear rooms. The switchgear rooms were 

selected for purging first because they 

contained important plant equipment, such as 

the auxiliary shutdown panel. The purge 

system is a non-safety-related system designed 

to remove CO 2 and smoke from various 

control building areas. Placing the purge 

system in service diverted air from the control 

room to the switchgear rooms, which lowered 

the pressure in the control room relative to the 

cable spreading room. This lowering of 

pressure in the control room may have allowed 

CO 2 from the cable spreading room to migrate 

up through penetrations into the control room. 

When the concentration of CO 2 reached 

5,000 ppm in the control room, the operators 

donned self-contained breathing apparatus 

(SCBA) as required by their procedures. The 

concentration of CO 2 in the control room 

reached a peak level in excess of 17,000 ppm 

before it began to decrease. The operators 

wore SCBA for approximately 6 hours until 

the CO 2 was successfully purged from the 

control room. It was discovered during this 

incident that the chairs in the control room 

' The current NRC toxicity limit for C02, specified in 

Regulatory Guide 1.78, is 10,000 ppm. Plant personnel 

exposed to CO, need to be protected by self-contained 

breathing apparatus before this concentration is reached. 

In the proposed revision to Regulatory Guide 1.78, the 

toxicity limit for CO 2 was raised to 40,000 ppm. This 

new limit is based on the Immediately Dangerous to Life 

and Health (IDLH) concentration of C0 2, established by 

the National Institute for Occupational Safety and Health 

(NIOSH).

were not suited for occupants who were 

wearing SCBA, so the operators were on their 

feet for hours. This resulted in a great deal of 

unnecessary stress and strain on the operators 

involved. 

3. At a nuclear power reactor on March 22, 

1992, the licensee performed a special test of 

the CO 2 fire suppression system in the cable 

spreading room. This test was conducted to 

check corrective actions taken following a 

CO 2 discharge in 1990. At the time of this test, 

the reactor had been shutdown and defueled. 

As a result of this test, CO 2 had intruded into 

the control room; this intrusion led to an 

unacceptable reduction in area oxygen level 

within a few minutes. Oxygen levels of 17% 

(at chest level) and 15%t (at floor level) were 

recorded; these levels were below the plant 

acceptance criterion of 19.5%. Essential 

control room personnel donned self-contained 

breathing apparatus (SCBA) and were able to 

remain in the control room. The lowered 

oxygen levels were caused by increased 

pressure in the cable spreading room, which is 

directly beneath the control room. Sealed 

penetrations between the two rooms leaked 

under the high differential pressure. 

4. On July 28, 1998, at a national laboratory, 

during preparation for electrical system 

preventive maintenance, a high-pressure CO 2 

fire suppression system unexpectedly actuated. 

The room in which workers were located was 

filled instantly with C0 2, creating whiteout 

conditions. Workers did not have the means of 

escaping safely. Emergency exit training was 

not provided; exit pathways were not clear; 

and, emergency breathing apparatus, exit 

pathway lighting, and emergency ventilation 

were not available. The accident resulted in 

one fatality, several life-threatening injuries, 

and significant risk to the safety of the initial 

rescuers.

III NUREG/CR-0041, Revision I
6.13 Oxygen-Deficient Environments 

6.13.1 Oxygen Deficiency 

Oxygen is the component of the atmosphere 

we breathe that is necessary to sustain life. 

The earth's atmosphere (air) is composed of 

the gases listed in table 6-1. 

Table 6-1. Relative percent volume and the 

partial pressures of the gases that comprise air. 

Partial 

Pressure 

Gas Volume % mm Hg at 

Sea Level 

Nitrogen 78.1 593 

Oxygen 20.9 159 

Argon 0.9 7.1 

Other* 0.1 

* Carbon dioxide, neon. krypton, helium 

and water vapor. 

Oxygen deficiency is a hazard because the 

amount of oxygen that can be transferred from 

the alveoli to the blood is reduced. An 

atmosphere that is, or might be, deficient in 

oxygen should always be a matter of concern. 

Such atmospheres may result from a reduction 

in ambient atmospheric oxygen content by 

displacement or consumption, from reduced 

atmospheric pressure, or from a combination 

of these. Breathing oxygen-poor air can cause 

physiological problems that if severe enough 

can impair a worker's judgment and motor 

skills, and potentially lead to permanent injury 

or death. 

The susceptibility to reduced oxygen varies 

somewhat among individuals. The range of 

oxyhemoglobin saturation at a given oxygen 

partial pressure shown in Figure A.I in ANSI 

Z88.2-1992 presumes that exposed individuals 

have a red blood cell count within the normal 

range. A low count will decrease the oxygen 

available to the brain. Licensees might 

consider including a red blood cell count in 

the respirator medical screening program, and 

investigating any history of anemia, for those

individuals who will be exposed to oxygen

deficient environments. 

6.13.2 Causes of Oxygen-Deficient 

Environments 

An oxygen-deficient environment can be 

created in two ways: 

"* Reduction of the percent oxygen by 

volume in the air in the work 

environment; or 

"• Reduction of the atmospheric pressure in 

the work area, which has the same effect 

as increasing the elevation above sea 

level. 

Reduction of the Percent Oxygen by Volume 

This situation can result from the oxygen 

being displaced by another gas, or by the 

consumption of oxygen by fire or other 

methods of oxidation, or removal by other 

methods. It is the most common form of an 

oxygen deficiency hazard, warranting extreme 

care when entering confined spaces, especially 

when inert gases are in use (e.g., TIG welding, 

tank inerting, etc.) Oxygen can be consumed 

during fires, by oxidation of organic matter, 

oxidation of iron (rust) in a tank, controlled 

burning operations (flame cutting, brazing, 

etc.), other chemical reactions, and simply by 

people breathing. For this reason, confined 

spaces should be clearly identified, entry into 

them tightly controlled, and work in them 

closely monitored. 

Oxygen-deficient atmospheres are most often 

found in enclosed or inerted spaces such as a 

pit (even though the top may be open), or a 

tank. In an emergency at a nuclear facility, an 

oxygen-deficient atmosphere may be created 

by a sudden release of a gas or vapor into an 

enclosed space thereby displacing the oxygen. 

A fire or other rapid chemical reaction will 

have the same result. Decomposition of 

organic matter in an enclosed space that

NUREG/CR-0041, Revision 1 112
consumes the available oxygen is another 

potential source of oxygen deficiency. An 

atmosphere that contains very little oxygen 

(less than 6% by volume at sea level) can be 

considered totally inert. The hazards to an 

unprotected individual in this environment are 

catastrophic, with a person being incapacitated 

after only a few breaths. Death will most 

certainly occur within 4-6 minutes without 

timely rescue. 

Several incidents involving oxygen-deficient 

environments are described below. 

1. In September, 1976, at a commercial 

nuclear power plant, two workers were killed 

in a recirculation pit (sump) by asphyxiation 

from argon inerting gas used to support 

welding on stainless steel piping. After the 

welding was completed, gas leakage from the 

faulty argon purge-pipe connection filled the 

pit. When a workman entered the pit to 

remove the purge connection he was 

overcome by the inerted atmosphere. He and 

one of two fellow workers attempting rescue 

were killed. A licensee safety review of the 

incident revealed several work practice 

deficiencies including: 

"* Local ventilation for the pit was available, 

but not used before entry; 

"* Although the equipment was available, 

oxygen air sampling was not performed; 

and 

"* A "buddy system" for the first entry into a 

confined space was not employed. 

2. At another nuclear power reactor in 

August, 1985, with the plant in a cold, 

shutdown condition, a nitrogen inerting 

blanket was placed on a moisture separator 

reheater. The nitrogen leaked past several shut 

valves into the main condenser. A non

licensed operator, while walking down the 

condensate system, stopped near the open 

condenser manway. The operator lost 

consciousness because of an apparent local 

IDLH area created by nitrogen escaping the 

condenser. An accompanying assistant 

provided prompt and effective rescue/first aid

and the operator was transported to the 

hospital. No permanent injury resulted from 

the incident. As a result of a licensee review of 

the lessons learned from the event, the 

licensee has improved its hazards controls 

program for using inerting gases by increasing 

atmospheric sampling, providing appropriate 

hazard postings to alert workers, and 

analyzing the potential effect on associated 

systems (e.g., potential leak paths). 

3. A health physics technician at a nuclear 

power reactor was overcome by an oxygen

deficient atmosphere in a steam generator 

(SG). The secondary-side of SGs are often 

nitrogen-inerted to minimize oxygen uptake 

during non-operational periods. In this case, 

the wrong SG was purged of its inerting 

atmosphere, and an HP technician (when 

entering the still-inerted SG) was overcome. 

Another HP technician on the scene promptly 

pulled the asphyxiated technician from the 

IDLH area. No lasting injuries resulted from 

this event. 

Reduced Atmospheric Pressure 

This situation always occurs with increasing 

altitude, and/or with decreasing atmospheric 

pressure, and can be brought about in a reactor 

containment vessel that is under a partial 

vacuum. The oxygen percent by volume may 

remain at 20.9%, but the PPO2 will be lower 

than normal and the body's ability to utilize 

the 02 will therefore be reduced. It's the 

partialpressure of oxygen (PpO2), not the 

oxygen percentage, that drives it from the air 

in the lungs, through the walls of the alveoli 

and into the bloodstream. 

The partial pressure (pp) of oxygen (or any 

gas) equals its fractional concentration times 

the total atmospheric pressure. Atmospheric 

pressure at sea level is 760 mm Hg. Since air 

contains approximately 21 % 02, then the ppO2 

at sea level is 

760 mmHgx0.21= 160 mmHg.

113 NUREG!CR-0041, Revision 1
Table 6-2. Oxygen partial pressure (mm Hg) 

at various altitudes.

The ratio of these gases to one another is the 

same, whether measured at sea level or on the 

top of Mt. Everest. The partial pressure of 

oxygen decreases, however, as elevation 

increases, since atmospheric pressure decreases. 

As shown in Table 6-2, the greater the altitude, 

the lower the atmospheric pressure and the 

lower the PPO2. We know that people live and 

work at high altitudes, and do so with little or 

no physiological effect, because they are 

acclimated. The human body can adapt to the 

reduced PPO2 levels, up to an elevation of 

roughly 17,000 feet, by making compensating 

changes to its respiratory, cardiovascular and 

hematopoietic systems. Complete 

acclimatization requires about four weeks 

residence at the ambient PPO2. 

When people who are not acclimated work in 

areas of reduced PPO2, they will quickly 

experience a feeling of fatigue. A given work 

rate in an environment of reduced PPO2 

produces a higher breathing rate, a greater 

heart rate, and possible other symptoms of 

fatigue that, under normal conditions (i.e., 

near sea level), would not be customary at that 

work load. If a worker moves from a location 

at sea level to take ajob at a facility at a high 

elevation, that worker will become acclimated 

within several weeks. During these weeks of 

acclimation the worker is not considered to be 

at risk from oxygen deficiency. The more 

significant situation would be when workers 

are required to work inside structures that are 

well below atmospheric pressure. Due to the 

relatively short exposure to these low-pressure 

work environments, their bodies are not able 

to acclimatize.

Comparisons-Reduced Atmospheric Pressure 

1. The Federal Aviation Administration 

requires that the cabins of passenger

carrying aircraft be pressurized when they 

go above 12,500 feet altitude. 

2. Some un-acclimatized people experience 

several effects of oxygen deficiency (e.g., 

headache, lightheadedness) at elevations 

above 5,000 feet (e.g., Denver, Colorado). 

3. At altitudes comparable to Pike's Peak 

(elevation 13,000 feet) and Quilcha, Chile 

(elevation 17,000 feet), sustained physical 

activity is difficult.5 

4. Permanent habitation is nearly impossible 

above 17,000 feet. Mountain climbers use 

supplementary oxygen above this 

elevation .' 

5. The summit of Mount Everest is 29,028 

feet above sea level. 

6.13.3 Oxygen Deficiency Immediately 

Dangerous to Life or Health (IDLH) 

Definition of IDLH 

The definition of IDLH based on 02 

deficiency has three parts.6 

1. If an area is a confined space and the air 

contains less than the normal 20.9% 02, 

the area is considered IDLH unless the 

reason for the 02 reduction is understood 

and is under control. 

2. Any space or area in which the 02 is less 

than 12.5% (95 mm Hg PpO2) at sea level 

atmospheric pressure (or the equivalent 

PPO2 for other elevations), the area or 

space is IDLH. 

3. If total atmospheric pressure is less than 

8.6 psia (450 mm Hg barometric pressure) 

the area or space is IDLH. This pressure is 

equivalent to a 14,000-foot altitude. Any 

combination of reduced percentage of 02 

and reduced atmospheric pressure that 

5 McArdle, W.D., F.I. Katch and V.L. Katch. Exercise 

Physiology. Second edition. Philadelphia: Lea and 

Febiger, 1986. 

6 ANSI Z88.2-1992, Section 7.3.1.

NUREG/CR-004 1, Revision 1 114
leads to an 02 partial pressure of less than 

95 mmHg makes the area IDLH. (Recall 

that barometric pressure times 02 

fraction equals the PPO2. For example, 

450 mm Hg x 0.21 = 94.5 • 95 mm Hg.) 

Potential 02 deficiency due to reduced 

oxygen percent and due to increased 

elevation/reduced atmospheric pressure both 

apply at all times. For the remainder of the 

discussion of oxygen deficiency, refer to 

Figure 6-3 for information on the relationship 

between percent oxygen and elevation 

(atmospheric pressure). For example, 02 

deficiency at sea level is defined as an 02 

content of 16% or less. At 6,000 feet, 02 

deficiency begins at 20% 02. This is the "sea-level equivalent" 02 deficiency point at 

6,000 feet. The information for Figure 6-3 was 

taken from ANSI Z88.2-1992 Table 2. 

14000 

13000 

12000 OxygenEn 

11000Breathing 

•,I 10000 

o 9000 .. -Deficier /) 8000 -- - - ... 

0 80 oJ2 7000 - • . . . .. 

C 6000 

S5000 

0 4000 

U.

Confined Space 

Any confined space that contains less than 

20.9% oxygen should be considered IDLH. A 

possible exception to this is discussed in 

Section 6.13.4 below. In this case it is only the 

percent 02 that is the problem, and 

atmospheric pressure is the same both inside 

and outside the confined space. If entry into 

such a confined space is necessary, SCBA 

would be required (as long as atmospheric 

pressure remains greater than 450 mm Hg) 

since it is technically an IDLH area. 

Classification of areas as IDLH based on low 

atmospheric pressure is discussed below. In 

IDLH situations, an SAR would provide 

adequate oxygen, but in case of air-supply 

failure the wearer would be exposed to a 

potentially lethal atmosphere. SCBA provides 

escape capabilities that a standard SAR does 

not.

11 12 13 14 15 18 17 18 19 20 21 

Percent Oxygen 

Figure 6-3. Oxygen deficiency and the relationship between percent 02 and elevation 

(atmospheric pressure), after ANSI Z8.2-1992, Table 2. See also Appendix F.

NUREG/CR-0041, Revision 1 115
IDLH-0 2 Concentration Less Than 12.5% 

Sea-Level Equivalent 

Areas where the oxygen concentration is less 

than 12.5% sea-level equivalent (see 

Figure 6-3) are also considered to be 

immediately dangerous to life or health 

(IDLH). This means that a person in this 

environment using an atmosphere-supplying 

respirator would suffer some effects of 

hypoxia if the respirator failed. These effects 

could, depending on how far below 12.5% the 

level was, either hinder his escape (which 

might lead to permanent injury or death), or 

might cause his rapid unconsciousness and 

death. An oxygen content less than 12.5% (or 

atmospheric pressure less than 450 mm Hg), 

corresponds to an oxygen partial pressure of 

48 mm Hg in the alveoli of the lungs.7 Under 

these conditions, the hemoglobin of the 

alveolar blood is 83% saturated with oxygen. 

The relationship between percent 02 saturation 

of hemoglobin and partial pressure of 02 in the 

alveoli is not linear. As alveolar pPO2 

decreases below 48 mm Hg, the percent 

hemoglobin saturation decreases precipitously 

and symptoms of oxygen deficiency quickly 

become manifest. 

Again referring to Figure 6-3, the IDLH point 

of 12.5% 02 at sea level is equivalent to 13% 

02 at 1,000 feet and to 14% at 3,000 feet. As 

explained above, SCBA is required for entries 

into IDLH areas because of its escape 

capabilities. 

IDLH-Atmospheric Pressure Less Than 

8.6 psia (450 mm Hg) 

An atmospheric pressure of 8.6 psia (450 mm 

Hg) corresponds to an elevation of 14,000 feet 

above sea level. This results in a PPO2 of 95 mm 

Hg. Under these conditions, even though the 

percent 02 is 20.9%, a person's judgment and 

coordination become very poor, and other 

symptoms and injuries may result. Individuals 

7 ANSI Z88.2-1992. Figure A.I.

working at or below this atmospheric pressure 

will not be afforded any protection by a SAR or 

open-circuit SCBA, since the problem is lack of 

pressure to drive the available 02 across the 

alveolar boundary and into the blood. The only 

realistic solution to this problem is to utilize an 

oxygen-enriched source of breathing gas. 

O_-IDLH at NRC-Licensed Facilities 

While it has been reported8 that a 30-minute 

exposure to 4E+6 DAC of Class W 239pU or to 

2E+6 DAC of Class Y 239pu will produce 

deterministic (nonstochastic) effects consistent 

with the definition of IDLH, the term IDLH 

does not realistically apply to most situations 

involving exposures to airborne radioactive 

material. The IDLH definition obviously 

applies to certain non-radiological hazards at 

an NRC-licensed facility. IE Information 

Notice 81-26, Part 4 describes a situation 

where a licensee permitted three workers 

wearing SCBA devices to enter a fully 

nitrogen-inerted reactor drywell 

(approximately 3% 02 by volume). The 

purpose of the entry was to locate the source 

of a primary system leak. Exposure of these 

individuals to this IDLH environment was for 

operational reasons, to avoid having to shut 

the plant down, ventilate the drywell for 

several hours, and then test the air before 

entry. In this case, the standby rescue 

personnel were not able to maintain the proper 

level of communication with the work party 

and were positioned on the other side of an 

airlock and unable to render immediate 

assistance in case of the malfunction of a 

worker's SCBA. Descriptions of several other 

incidents involving oxygen-deficient 

environments are contained in IE Information 

Notice 85-87. A complete list of respirator

related NRC bulletins, circulars, and notices is 

included in the front of this Manual. 

8 Bianconi, Charles J. "Selection of Respiratory 

Protection Devices for Use in Very High Concentrations 

of Airborne Plutonium." Operational Radiation Safety, 

August 2000, pp. S41-S43.

NUREG/CR-0041, Revision I 116
Non-IDLH-Reduced Percent 0,

Licensees should note that a number of older 

documents, the original NUREG-0041 (1976) 

included, list exposure to airborne radioactive 

materials in their definitions of what 

constitutes an IDLH environment. This is no 

longer considered valid and licensees may 

ignore such incorrect guidance in 

administering their respiratory protection 

programs. 

6.13.4 Oxygen Deficiency Non-IDLH 

Non-IDLH--Confined Spaces 

Workers entering a confined space where 

measured 02 concentration is less than 20.9% 

but more than 16% at sea level 9 should use a 

supplied-air respirator (SAR) under most 

circumstances. Entry may be made without 

respiratory protection only under unusual 

circumstances. Licensees should provide 

supplemental area ventilation if no respirators 

are used. For example, if after supplemental 

ventilation has been initiated, two 02 

measurements taken 20 minutes apart inside 

the confined space indicate that the 02 

concentration is increasing and is greater than 

16%, the licensee could conclude that the 

additional ventilation is correcting the problem 

and an entry without respiratory protection 

devices may be made. SARs should still be 

used if they will have no significant impact on 

radiation dose or on overall safety. In a 

situation such as this, licensees should follow 

their confined space entry procedure, which 

should include continuing periodic 02 

sampling inside the confined space, protection 

of the air supply, and arrangements to assist or 

rescue individuals making such an entry in 

case the situation deteriorates.

Oxygen deficiency non-IDLH can be defined 

as an area where the oxygen content is greater 

than 12.5% at sea level (or atmospheric 

pressure greater than 450 mm Hg, equivalent 

to an elevation of 14,000 feet -the IDLH 

level), but less than 16% at sea level (or 

atmospheric pressure less than 575 mm Hg, 

equivalent to an elevation of 7,500 feet). See 

Figure 6-3. 

This classification is for an oxygen content 

that will produce noticeable effects on non

acclimated healthy worker, yet is not IDLH. 

The hemoglobin of the alveolar blood is 92% 

saturated with oxygen at the upper end of this 

classification, and 84% at the lower end. See 

ANSI Z88.2-1992, Figure A. 1. To aid the non

acclimatized worker, and to allow for the 

uncertainty in the IDLH point among 

individuals, a supplied-air respirator should be 

used in this oxygen concentration range. 

Non-IDLH-Reduced Atmospheric Pressure 

The containment buildings of seven 

commercial nuclear power reactor plants are 

maintained at sub-atmospheric pressures 

(approximately 11 to 9 psia or 10,000 to 

12,750 ft elevation) while the reactors are 

operating. (Note that the actual elevation of 

the plant is immaterial if containment pressure 

is measured in psia.) This exposes personnel 

entering those containment buildings to an 

oxygen-deficient environment.10 Using 9 psia 

as the lowest operating pressure, three 

potential scenarios are possible (refer to 

Figure 6-3.): 

1. 02 = 20.9%; 

2. 02 less than 20.9% but greater than 20.2%; 

or 

3. 02 less than 20.2%. 

'0 U.S. Nuclear Regulatory Commission, memorandum 

of March 14, 1985 from LeMoine J. Cunningham. 

Subject: Breathing Apparatus for Entry into 

Subatmospheric Containments.

NUREG/CR-0041, Revision I

ANSI Z88.2-1992, Section 7.3.3.

Misinformation About IDLH

117
In the first case, when the 02 is consistently at 

20.9%, an entry would expose workers to an 

02 -deficient environment even though the 02 

level is at its atmospheric maximum. The 

usual approach to entering an 0 2-deficient 

environment-assignment of SARs-is not a 

solution in this case because the ambient air 

already contains the same percent 02 as a 

breathing air system would supply. The 02 

deficiency is due to reduced atmospheric 

pressure, which reduces the ppO2 and thus 

reduces the body's ability to utilize the 

oxygen. Short of repressurizing the 

containment building to more than 575 mm 

Hg (less than 7,500 ft elevation), the only 

solution is to increase the 02 content of the 

breathing gas supplied to the workers. 

The second case is similar to the first, except 

that a lower-than-normal percent 02 makes the 

situation more potentially hazardous since the 

IDLH level based on 02 deficiency occurs at 

about 20.2%. Assignment of SARs or open

circuit SCBAs will marginally improve the 

situation by increasing the 02 to 20.9%, but 

the workers will still be in an 0 2-deficient 

environment, and the level of stress they are 

exposed to will be increased by the respirators. 

Use of atmosphere-supplying respirators is not 

an effective solution to this problem. Also, 

ANSI Z88.2-1992 Table 2 recommends that if 

respirators are assigned for use at altitudes 

10,000 feet or higher because the 02 level is less 

than 20.9%, that those devices should provide 

0 2-enriched breathing gas. The NRC concurs 

with this recommendation. A minimum of 23% 

0, is needed at 10,000 feet. The 0 2-enriched 

breathing gas issue is discussed in section 6.13.6 

below. 

While entry into a confined space which is 02

deficient may be made without respiratory 

protection under unusual circumstances (see 

Non-IDLH--Confined Spaces above), it is not 

advisable in the two situations described here. 

In the third case, the workers would be 

exposed to an IDLH environment based on 02 

deficiency. As was the case above with SARs,

open-circuit SCBAs only provide air at 20.9% 

02 and are ineffective at protecting workers 

from oxygen deficiency at this atmospheric 

pressure. Use of oxygen-enriched breathing 

gas is the only solution to entries into an 

IDLH environment under these 

circumstances. 

6.13.5 Entry into an IDLH Environment 

Entry made into an IDLH (or potentially 

IDLH) environment is an extremely hazardous 

and potentially life-threatening operation and 

should only be undertaken in exceptional 

circumstances. A few such exceptional 

circumstances would be: 

"* Life-saving; 

"* Fire fighting; 

"* Stopping or preventing major release of 

radioactive material; or 

"* Stopping or preventing major property 

damage. 

These entries should be made in accordance 

with written procedures. 

Entries into IDLH environments' should be 

made only by individuals equipped with 

SCBAs operated in the pressure-demand mode 

(or positive-pressure mode for closed-circuit 

SCBA). Persons making such entries should 

use the "buddy system." The buddies should 

always have one another in sight. This in-sight 

criterion might not be possible in a fire

fighting situation, so in this case, some other 

accountability system should be used. 

There should be standby rescue persons 

equipped with SCBAs outside the IDLH area, 

but immediately ready to enter the area to 

rescue a person who is in trouble. The number 

of standby rescue persons should be sufficient 

to accomplish a rescue in a timely fashion if 

the occasion arises. In one incident, a diver 

entered a condensate storage tank at a nuclear 

power plant to perform a pre-maintenance 

" Except for IDLH based on 02 deficiency caused by 

decreased atmospheric pressure discussed previously.

NUREG/CR-0041, Revision I 118
inspection. He apparently did not recognize 

that a nitrogen blanket existed in the tank and 

entered without breathing apparatus. The diver 

lost consciousness and fell into the water. A 

standby diver and the safety line tender tried 

to pull the diver out of the tank but they were 

unsuccessful. The standby diver, also unaware 

of the nitrogen blanket, jumped into the tank 

without safety line or breathing apparatus, to 

attempt a rescue. The standby diver 

disappeared beneath the water and died in his 

rescue attempt. The first diver was later 

rescued and revived. In this case, even two 

individuals were not enough to extract the first 

diver. 

The NRC issued an information notice12 in 

1981 describing a non-emergency entry into a 

fully inerted boiling water reactor (BWR) 

containment. It contains more information 

about the NRC's position on exposing 

personnel to IDLH environments. 

6.13.6 Entry into a Reduced-Pressure 

Reactor Containment Building 

The reduced pressure of a sub-atmospheric

pressure containment building with absolute 

pressure of 9 psia is the equivalent of an 

altitude of approximately 12,750 feet. Thus, 

oxygen deficiency is a legitimate concern. A 

positive-pressure, open-circuit SCBA, 

although providing protection against any 

airborne contaminants which may be present 

in the space, will not protect against the 

oxygen-deficient atmosphere present because 

of the reduced atmospheric pressure. This is 

because the open circuit SCBA regulator, by 

design, reacts to the ambient pressure and will 

provide breathing air at a pressure only 

slightly above ambient. This still results in 

insufficient oxygen being available to the 

wearer. Therefore, the atmosphere supplied to 

the wearer of an open-circuit SCBA with 

I IE Information Notice No. 81-26 Part 4, "Personnel 

Entry Into Inerted Containments," August 28, 1981.

typical grade D air specifications will 

technically and realistically be oxygen

deficient. 

The amount of oxygen enrichment necessary 

to adequately protect a respirator user in a 

reduced-pressure environment will be 

dependent upon the containment's total 

pressure. If, for example, a sub-atmospheric 

containment's atmospheric pressure is 9 psia 

(465 mm Hg), the percentage of oxygen in the 

breathing gas must be increased to 

approximately 35%. This is calculated by 

dividing ppO2 at sea level by the atmospheric 

pressure in the work environment, in this case 

760 mm Hgx0.209 = 0.342 = 34.2% 

465 mm Hg 

Therefore, by providing breathing air with 35% 

02, the SCBA wearer will be assured of 

having sufficient oxygen to maintain normal 

bodily function. However, operating open

circuit SCBA's with other than grade D

quality air voids the equipment's NIOSH 

certification. One nuclear utility has applied to 

the NRC in accordance with 10 CFR 

20.1703(b) for permission to use oxygen

enriched breathing gas in its SCBAs for entry 

into sub-atmospheric containments. The 

licensee contracted with the National 

Aeronautics and Space Administration 

(NASA) and Lawrence Livermore National 

Laboratory (LLNL) to conduct controlled 

testing. NASA's White Sands Test Facility 

(WSTF) examined ignition and combustion 

within the SCBA regulator, and the 

compressive heating of hoses and regulator 

soft goods (e.g., O-rings). The test results 

showed that the SCBA materials did not 

promote ignition up to an oxygen 

concentration of 51% at 4,500 psig. However, 

with hydrocarbon contaminants present (not 

normally found in a well-maintained SCBA) 

some non-catastrophic failures occurred under 

worst-case conditions, but only during initial 

pressurization of the appartus. Further testing 

revealed that the manufacturer-supplied 

silicon facepiece used with the SCBA met the

119 NUREG/CR-004 1, Revision 1
National Fire Protection Association's flame 

and heat test. Based on the results of these 

tests, the NRC granted the licensee's request 

to use oxygen-enriched breathing air with 

SCBAs specifically designated for use inside 

the reduced-pressure containment structures. 

A closed-circuit, positive-pressure SCBA's 

operation is also affected by reduced ambient 

pressure, since the regulator senses the lower 

ambient pressure. Due to design 

characteristics of closed circuit apparatus, the 

recirculating breathing gas starts out at 40

60% oxygen enrichment and over the course 

of the service life may reach upwards of 80

90% oxygen enrichment. The carbon dioxide 

evolved during respiration is chemically " scrubbed" from the circulating gas. 

Routine or emergency entries should not be 

made into sub-atmospheric containment 

buildings without breathing apparatus that 

provides an oxygen-enriched supply of 

breathing air. 

6.13.7 Confined Spaces 

There is a distinct possibility in a nuclear 

facility that occasionally, an emergency entry 

may have to be made into what is called a 

"confined space." This may include enclosures 

that have limited openings for entry or exit, 

such as storage tanks, stacks, pits, reactor 

vessels, ventilation and exhaust ducts, and any 

open-topped space that is more than 4 feet in 

depth and not equipped with adequate 

ventilation. 

Considering that such an enclosure may also 

be oxygen-deficient and/or contain a high 

concentration of radioactive and/or non

radioactive airborne contaminants, the 

environment should be considered as IDLH, 

and attendant respiratory protection required 

for entry and work until it has been properly 

sampled and ventilation established, or until 

an adequate surveillance and control program 

has been established. In addition to the

respiratory requirements, special precautions 

should be taken to ensure the safety of the 

workers when working in confined spaces. 

These include continuous communications, 

standby rescue personnel, and use of signal 

lines and/or lifelines. Additional procedures 

should exist for the use of SCBA for entry into 

Limited Egress/Confined Space (LE/CS) 

during emergencies. These procedures should 

allow for the larger space required by persons 

wearing SCBA, require standby rescuers to 

have SCBAs, and provide for removal of 

people by lifeline if necessary. 

It is only human nature to attempt immediate 

rescue of a disabled person before evacuating 

an area. At the onset, it is unlikely that the 

extent or severity of an emergency will be 

known. Remaining in the emergency area to 

effect a rescue while wearing inadequate or no 

respiratory protection may jeopardize 

everyone involved. The following quote 

concerning emergencies in confined spaces is 

applicable to other emergency situations. "An 

important consideration in responding to an 

emergency is to avoid making the situation 

worse by placing yourself in danger. For 

example, an unconscious person in a confined 

space usually cannot be rescued by a single 

person. Proper equipment and assistance 

generally are needed to retrieve such a person. 

Under no circumstances should you 

independently enter a confined space, even if 

someone else is in danger or if you believe it 

is safe to enter. The entry of an ill-equipped 

rescuer without proper knowledge of the 

situation could result in two fatalities rather 

than one.... , The rescue of injured, trapped, 

or incapacitated workers in an emergency that 

may involve hazardous environments is 

usually more successful when left to trained 

personnel. 

13 Los Alamos National Laboratory. "Health and Safety 

Guide." LALP-82-39. <http://lib-www.lanI.gov/la

pubs/00212245.pdf.>

NUREG/CR-0041, Revision I 120
6.14 Use of Respirators by Non-Licensee 

Personnel 

Firefighters 

When an outside fire department responds to a 

fire or other emergency at a licensee's facility, 

the licensee may presume that the firefighters 

meet the respiratory protection program 

requirements that apply to them. They may 

use their own equipment or the licensee's 

equipment. No retrospective evaluation of fit 

testing, medical screening or training needs to 

be done. An APF of 10,000 may be used for 

dose assessment if one is required. 

Radiological release of the firefighters' 

equipment after the emergency should be in 

accordance with the licensee's procedures. 

It is suggested that licensees coordinate with 

local emergency response organizations to 

work out potential problem areas before an 

emergency occurs. Some of these areas might 

be compatibility of SCBA air cylinders, 

availability of replacement cylinders, site 

familiarization, and the on-site capability for 

refilling these cylinders.

Divers 

While diving operations are a very specialized 

application of respiratory protection, they are 

much more of a planned occurrence than is 

fire fighting. Therefore, licensees should take 

the opportunity to verify the diving 

contractor's compliance with 29 CFR 1910 

Subpart T, Commercial Diving Operations 

(29 CFR 1910.401-1910.441). 

Other Contractors 

The requirements of a licensee's respiratory 

protection program should apply to contractors 

and permanent employees alike. If a contractor 

provides specialized respiratory protection 

equipment for a specific task (e.g., sand

blasting) the RPA should examine the 

equipment to ensure that it meets the 

licensee's criteria for NIOSH approval, like

new condition, etc., described elsewhere in 

this Manual.

121 NUREG/CR-0041, Revision I
References and Resources

I. Steinmeyer, Paul R. "Facial Hair Policy in a Respirator Program." Radiation Protection 

Management, Vol. 6, No. 5 (Sept/Oct 1989), pp. 52-56. <http://www.radpro.com>. 

2. Compressed Gas Association. "Compressed Air for Human Respiration," CGA G-7-l1990. 

3. Compressed Gas Association. "Commodity Specification for Air," CGA G-7.1-1997. 

4. Gee, Earl F. and John P. Hale. "Combating the Stresses of Respirator Use." Radiation Protection 

Management, Vol. 6, No. 4 (July/Aug 1989), pp. 49-54. <http://www.radpro.com>. 

5. "'Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure 

Indices." American Conference of Governmental Industrial Hygienists (ACGIH), current edition. 

6. Bernard, Thomas E. "Features of Heat Stress Control." Radiation Protection Management, Vol. 6, 

No.4, pp. 30-36. <http://www.radpro.com>. 

7. Bernard, T.E. and W.L. Kenney. "Heat Stress Management Program for Nuclear Power Plants." 

Electric Power Research Institute (EPRI) Report NP4453, 1989. 

8. Criteria for Recommended Standard.. Occupational Exposures to Hot Environments, Revised 

Criteria 1986, National Institute for Occupational Safety and Health (NIOSH), DHHS (NIOSH) 

Publication No. 86-113, 1986. 

9. Skaggs, B.J.. J.M. Loibel, K.D. Carter and E.C. Hyatt. "Effects of Temperature and Humidity on 

Respirator Fit Under Simulated Work Conditions." NUREG/CR-5090, LA- 11236. July 1988. 

10. -Interim Guidelines for Protecting Firefighting Personnel from Multiple Hazards at Nuclear Plant 

Sites." NP-6434 (July 1989). Electric Power Research Institute, Palo Alto, CA. 

!I. Electric Power Research Institute. "Effects of Protective Clothing on the Cardiorespiratory 

System of Workers at Elevated Temperatures." EPRI RS-107710, May, 1997. 

12. NUREG/CR-3551, "Safety Implications Associated with In-Plant Pressurized Gas Storage and 

Distribution Systems in Nuclear Power Plants" (May 1985) provides a detailed, thorough 

technical review and offers a broad perspective for many aspects of using compressed gases. The 

NUREG discusses many elements important to plant safety that relate directly to a non

radiological hazards control program and, personnel respiratory protection, including (1 ) physical 

properties and hazards of gases, (2) failure modes of gas systems, (3) incidents, and (4) potential 

hazards. 

13. IE Information Notice 81-26, Part 4, "Personnel Entry Into Inerted Containment" (August 1981), 

is another useful reference which discusses a non-emergency entry into a fully inerted BWR 

containment at power. The notice discusses the entry hazards, provides guidance, and lists other 

pertinent references. 

14. IE Information Notice 85-87, "Hazards of Inerting Atmospheres" (November 18, 1985). 

15. IE Circular 80-03, "Protection from Toxic Gases" (March 1980). 

16. IE Information Notice 83-62, "Failure of Redundant Toxic Gas Detectors Positioned at Control 

Room Ventilation Air Intakes" (September 1983). 

17. NRC Information Notice 99-05, "Inadvertent Discharge of Carbon Dioxide Fire Protection System 

and Gas Migration" (March 1999). 

18. IE Information Notice 78-03, "Potential Explosive Gas Mixture Accumulations Associated with 

BWR Offgas System Operation," (February, 1978). 

19. IE Information Notice 82-28, "Hydrogen Explosion While Grinding in the Vicinity of Drained and 

Open Reactor Coolant System (July 13, 1982). 

20. IE Information Notice 86-43, "Problems with Silver Zeolite Sampling of Airborne Radioiodine" 

(June 10, 1986). 

21. McArdle, W.D., F.I. Katch and V.L. Katch. Exercise Physiology. Second edition. Philadelphia: 

Lea and Febiger, 1986.

NUREG/CR-0041, Revision I 122
22. U.S. Nuclear Regulatory Commission, memorandum of March 14, 1985 from LeMoine J. 

Cunningham. Subject: Breathing Apparatus for Entry into Subatmospheric Containments. 

23. Los Alamos National Laboratory. "Health and Safety Guide." LALP-82-39. <http://lib

www.lanl.gov/la-pubs/00212245.pdf.> 

24. Regulatory Guide 8.25, "Air Sampling in the Workplace," Rev. 1, June 1992. 

25. NUREG-1400, "Air Sampling in the Workplace," September 1993. 

26. Bianconi, Charles J. "Selection of Respiratory Protection Devices for Use in Very High 

Concentrations of Airborne Plutonium." Operational Radiation Sqfety, August 2000, 

pp. S41-S43.

123 NUREG/CR-0041, Revision I
APPENDIX A 

The Human Respiratory System 

and Particle Collection Mechanisms

The human respiratory system (Figure A-1) 

can be divided into four sections]: 

"* The extrathoracic (ET) region includes the 

anterior nose (ET 1), and the posterior nasal 

passages, larynx, pharynx, and mouth 

(ET2); 

"* The bronchial region (BB) consisting of 

the trachea and the left and right bronchi; 

"* The bronchiolar region (bb) consisting of 

the bronchioles and terminal bronchioles; 

and 

"* The alveolar-interstitial region (AI) 

consisting of the respiratory bronchioles, 

the alveolar ducts and sacs with their 

alveoli, and the interstitial connective 

tissue. 

Extrathoracic (ET) Region 

Air is normally inspired through the nose and 

pharynx into the larynx. In case of a nasal 

obstruction, or when breathing demands 

exceed the nasal airflow capacity, additional 

air is inspired through the mouth. The ET 

region humidifies and increases the 

temperature of inspired air. 

Bronchial (BB) Region 

The BB region consists of the trachea, the 

main bronchi, and six more generations of 

sub-branches off the bronchi. The region also 

includes associated lymph vessels and lymph 

nodes. The BB region conducts air from the 

ET region into the bb and Al regions where 

0 2-CO 2 exchange takes place. These 

SInternational Commission on Radiological Protection 

(ICRP). "Human Respiratory Tract Model for 

Radiological Protection." Publication 66. Oxford: 

Pergamon Press. 1994.

conducting airways are tubes lined by ciliated 

respiratory mucosa and contain variable 

amounts of muscle and/or cartilage in their 

walls. 

Bronchiolar (bb) Region 

This is the second half of the air conducting 

system and contains the next seven branches 

(generations) of the bronchial tree called the 

bronchioles. The last set of these are called 

terminal bronchioles. These are also lined 

with mucous. Bronchi are distinguished from 

bronchioles primarily by the presence of 

cartilage in their walls. All airways beyond 

the terminal bronchioles contain alveoli, 

where most of the gas exchange in the lungs 

takes place. Each person's lungs contain 

between 25 million and 100 million 

bronchioles. 

The Alveolar-Interstitial (Al) Region 

The Al region contains the final ten 

generations of the bronchial tree, which are 

the respiratory bronchioles and the alveolar 

ducts. It also includes the interstitial 

lymphatic tissues and lymph vessels, and the 

bronchial lymph nodes. Gas exchange, the 

main function of this region, occurs in the 

alveolus where the thin laminar capillary 

blood flow and inspired air are separated only 

by a thin tissue layer. Gas exchange takes 

0.25 seconds or 1/3 of the total transit time of 

a red cell. The oxygen-rich air in the lungs 

transfers oxygen to the red blood cells in the 

capillaries, and CO 2 from the same red blood 

cells is transferred to the air in the alveoli. 

Hemoglobin on the red blood cells attracts 02 

when oxygen is plentiful, and attracts CO 2 

when carbon dioxide is plentiful. The driving

A-1 NUREG/CR-0041, Revision 1
Extrathoracic (ET) 

Thoracic 

J Bronchial (BB) 

p I 

"Bronchiolar (bb) 

'Alveolar Interstitial (AI)

Respiratory Bronchioles

Alveolar Duct + Alveoli

Figure A-I. The human respiratory system model, after ICRP Publication 66, 1994.

NUREG/CR-0041, Revision 1

Bronchus

A-2
force in both of these transfers is the partial 

pressure of each gas. Gas will always move 

from an area of higher pressure to an area of 

lower pressure. The greater the pressure 

differential the faster the transfer will be. See 

Table A-I below. The entire blood volume of 

the body passes through the lungs each minute 

in the resting state (i.e., 5 liters per minute). 

The total surface area of the adult lung varies 

from about 300 ft2 (28 M2

) while at rest to 

about 1,000 ft2 (93 M2 ) at deep inspiration 

(equivalent to the size of a tennis court). In 

contrast the skin surface of an adult is roughly 

20 ft2 (1.9 M2 ). Each person's lungs contain 

about 300 million alveoli. The alveolar walls, 

which separate the alveolar gas from the 

capillaries, are only I or 2 cells thick, while

the epidermis and dermis are several 

millimeters thick. The large area of the 

respiratory system means that most inhaled 

contaminants will be transferred to the blood 

quickly. Also, oxygen deficiency will act 

quickly on an individual. The delicate nature 

of the alveolar sacs means that they can be 

easily damaged. Approximately 10,000 liters 

of air are inspired per day. 

Particle Deposition in the Lung 

Particles in an air stream, such as dirt or dust 

particles in the air breathed by a worker, can 

vary in size from 0.001 p.m to as much as 

100 Vtm. Particle sizes are given in terms of 

their activity median thermodynamic diameter

Table A-1. Partial pressures of the various breathing gas constituents in 

inhaled air at sea level compared to alveolar gas. 

PP Inhaled Air Direction of PP Alveolar Gas 

Gas (mm Hg) Flow (mm Hg) 

02 159 110 

N 2 593 569 

H20 (vapor) 3.8 47 

CO 2 0.2 40 

Table A-2. Fractional deposition (%) of various size particles in each region of 

the respiratory tract for nose breathers. 

Activity Median ET, ET2 BB bb Al 

Diameter (jim) 

0.001 40 40 8 10 0.4 

0.005 18 20 6 30 30 

0.01 9 11 3 20 50 

0.05 3.5 3.8 1 7.5 34 

0.1 3.5 3.5 0.8 5 22 

0.5 14 18 1 2 12 

1.0 20 25 1.5 1.5 10 

5 35 40 2 1.4 5 

10 35 40 1.5 0.7 2.5 

50 26 26 0.18 0.04 0.08 

100 26 26 0.04 -0- -0-

A-3 NUREG/CR-0041, Revision 1
(AMTD) for very small particles, or their 

activity median aerodynamic diameter 

(AMAD) for larger particles. This is a 

measure of how fast they will drop out of a 

volume of air and no longer be airborne (i.e., 

settling velocity). Particles will be collected 

with varying degrees of efficiency in the 

various portions of the respiratory tract 

depending on their aerodynamic diameters. 

Table A-2 and Figure A-2 show the deposition 

fractions by particle size in the respiratory 

compartments for nose breathers. Table A-3 

and Figure A-3 provide the same information 

for mouth breathers. Note that mouth 

breathers consistently draw a higher 

percentage of particles from 0.1 to 100 gtm 

AMAD into the Al compartment. 

As can be seen in Table A-2 and Figure A-2, 

large particles are relatively easy to remove 

from air inhaled through the nose. They tend 

to travel in a straight line due to inertia, so 

many are collected on the mucous-covered 

nasal hairs, or impact the mucous-covered 

0 10 T 

0) 

Vt i 

.0 

a)

0.0 

0.001 0.01 0.1 

Activity Median

walls of the ET2 region as the air stream 

changes velocity and direction. 

Very small particles are also relatively easy to 

collect. Since they have negligible mass, they 

have virtually no inertia. So in contrast to the 

straight-line travel of large particles, very 

small particles travel in a torturous path even 

when entrained in a moving stream of air. 

This erratic movement increases their 

probability of coming into contact with the 

walls of the upper airways and being 

collected. This erratic movement is referred to 

as Brownian motion. 

Small Particle Collection-Brownian Motion 

In 1827 the English botanist Robert Brown 

noticed that pollen grains suspended in water 

jiggled about under the lens of the microscope, 

following a zigzag path. Even more 

remarkable was the fact that pollen grains that 

• ••*• "°ET • 

L BB 

1 0 Al 

1 10 100

Diameter (pm)

Figure A-2. Fractional deposition (%) of various size particles in each region of the 

respiratory tract for nose breathers.

NUREG/CR-0041, Revision I A-4
Table A-3. Fractional deposition (%) of various size particles in each 

region of the respiratory tract for mouth breathers. 

Activity Median 

Diameter (pm) ET, ET2 BB bb Al 

0.001 14 52 13 19 0.7 

0.005 7 18 6 30 30 

0.01 4 10 3 20 50 

0.05 1.5 3 0.9 7 30 

0.1 1 2.5 0.7 5 25 

0.5 2 4 1.5 2 14 

1.0 5 9 3 2.5 16 

5 12 35 10 4 12 

10 12 45 8 2.5 7 

50 10 40 1.5 0.18 0.3 

100 10 40 0.4 0.03 0.04

0.0 Im 

0.001 0.0 0.1 1 10 

Activity Median Diameter (l.m)

-*-ET 

-6- ET 

-s--BB 

-•&- bb 

--- AI

100

Figure A-3. Fractional deposition (%) of various size particles in each region of the 

respiratory tract for mouth breathers.

NUREG/CR-0041, Revision 1

0 

0 

C. 

4

0 

0 

4) 

w

A-5
had been stored for a century moved in the 

same way. In 1889 G.L. Gouy found that the 

"Brownian" movement was more rapid for 

smaller particles (e.g., we do not notice 

Brownian movement of cars, bricks, or 

people). In 1877, Desaulx correctly theorized 

that a suspended particle is constantly and 

randomly bombarded from all sides by 

molecules of the fluid in which it is 

suspended. If the particle is very small, the 

hits it takes from one side will be stronger than 

the bumps from the other side, causing it to 

jump. These small random jumps are what 

make up Brownian motion. Einstein 

developed the first mathematical theory of 

Brownian motion in 1905 and received the 

Nobel Prize for his effort. Brownian motion 

increases the likelihood of very small particles 

coming into contact with the fibers of a 

respirator filter, or a mucous-covered nasal 

hair, or the mucous membrane that lines the 

upper regions of the respiratory tract, and 

being removed from the inspired air. 

Large Particle Collection-Impaction 

Brownian motion has little effect on large 

particles in a moving air stream, and their 

greater mass means that they have more inertia 

than small particles, so they tend to travel in a 

straight line. They will continue to travel in a 

straight line even if the airway turns (e.g., in 

the ET2 Region). If a large particle impacts a 

filter fiber, or a mucous-covered nasal hair, or 

the mucous membrane that lines the upper 

regions of the respiratory tract, it is likely to 

be collected. Very large particles (>100 jim) 

have so much mass that they will not remain 

airborne for very long. Even if they are 

inhaled few of them will get past the ET 

region. 

Particle Size Summary 

As a general rule, very large particles in an air 

stream are easy to collect due to inertia, and 

very small particles are easy to collect due to

Brownian motion. An examination of the 

collection probability versus particle size 

reveals that particles roughly in the range of 

0.3 ilm MMAD are the most difficult to 

remove by filtration. This was the basis for 

choosing dioctyl pthalate (DOP) as the 

challenge medium for respirator filters. When 

DOP oil is vaporized and the vapor is cooled, 

the size of the tiny oil droplet formed, called 

the condensation nucleus, has an MMAD of 

roughly 0.3 ptm. 

Defense Mechanisms of the Lung 

The Extrathoracic Region (ETI) is equipped 

with a pre-filter-the nasal hairs-which are 

especially effective at removing very large and 

very small particles from inhaled air. Particles 

deposited in the anterior portion of the ET 

region cause an increase in mucous production 

and are usually removed by sneezing or nose 

blowing. In the posterior portion of this region 

(ET 2) the air channels narrow (which increases 

the air velocity) and change direction several 

times. The air stream again turns 900 as it 

passes through the pharynx and larynx and 

enters the trachea. These changes in velocity 

and direction cause entrained particles to 

impact with the walls of the nasal cavity and 

pharynx and to be collected on the mucous 

membrane. The particles captured in the ET2 

region also cause an increase in mucous 

production, which leads to coughing. This 

particle-laden mucous may be spit out, but is 

most often swallowed. Particles trapped in the 

ET region have a clearance half-time of a few 

minutes to a few hours. 

The lining of the Bronchial Region (BB), and 

to a lesser extent the Bronchiolar Region (bb), 

contain ciliated cells. Dust particles in the air 

are collected when they come in contact with 

the mucous-covered walls. These particles 

stimulate the trachea and bronchi to produce 

more mucous. The small hair-like cilia 

covering the walls of much of these regions 

move in such a way as to sweep the dirt-laden 

mucous to the top of the trachea. Cilia beat at

NUREG/CR-0041, Revision 1 A-6
1,000 to 1,500 cycles per minute resulting in 

the movement of the mucus blanket at 0.5 to 

I mm per minute in small airways and 5 to 

20 mm per minute in the trachea and main 

bronchi. All material that accumulates in 

these airways is removed in about 24 hours. 

Together the ciliated cells and the mucous 

blanket constitute the so-called mucociliary 

escalator. From the top of the trachea the dirt

laden mucous is either swallowed or 

expectorated. Clearance half-times from these 

regions range from 2 hours to 70 days. 

Alveolar macrophages constitute a small 

percentage of the cells in alveoli, but they 

represent the main defense mechanism in the 

Al Region. They are part of the mononuclear 

phagocyte system and are derived primarily

from monocytes (a type of white blood cells). 

Macrophages wander through the lung and are 

the only alveolar clearance mechanism for 

particulate material that has escaped the 

collectors in the upper regions of the 

respiratory tract. To leave the lungs, these 

cells with their captured particles may either 

migrate to the nearest bronchiole and exit via 

the mucociliary escalator, or they may exit via 

the blood vessels or lymphatic system. They 

may also accumulate in the regional lymph 

nodes. Clearance half-times for particles in 

the Al region range from a month to nearly 

20 years.

A-7 NUREG/CR-0041, Revision 1
References and Resources 

<http://edcenter.med.cornell .edu/CUMCPathNotes/Respiratory/Respiratory.html> 

International Commission on Radiological Protection (ICRP). "Human Respiratory Tract Model for 

Radiological Protection." Publication 66. Oxford: Pergamon Press. 1994.

NUREG/CR-0041, Revision I A-8
APPENDIX B 

Calculation of Effective Tritium APF for SAR 

Given: 

s = intake through skin 

10 = intake through lung without respiratory protection 

1-, intake through lung with respiratory protection 

S+Io 

Effective Protection Factor = PFEff - ____0 

S+Iw 

and I,, APF 

Thus, PFE - _ -S+I_ (S+Io)APF 

S I (SXAPF)+ 1. 

APF 

If 1/3 of tritium is absorbed through the skin, let S = I and 1. = 2. 

3 APF 

PFEff = 

APF+2 

3×10 30 

If the APF = 10, PFEff=- =3=2.5 

10+2 12 

3x100 300 

If the APF = 100, PFEff= OO = 30=2.94 

100+2 102 

3 x 1,000 3,000 If the APF = 1,000, PFEff- - =2.99 

1,000 + 2 1,002 

3 x10,000 30,000 If the APF = 10,000, PFEff = 310,000 _ 30,002 = 2.999 10,000 + 2 -10,002

B-1 NUREG/CR -0041, Revision I
APPENDIX C 

Respirator Medical Screening Questionnaire 

(From 29 CFR 1910.134 Appendix C. 

Use of this questionnaire is mandatory in an OSHA respiratory protection program.) 

To the employer: Answers to questions in Section 1, and to question 9 in Section 2 of Part A, do not 

require a medical examination. 

To the employee: Can you read (circle one): Yes/No 

Your employer must allow you to answer this questionnaire during normal working hours, or at a time 

and place that is convenient to you. To maintain your confidentiality, your employer or supervisor must 

not look at or review your answers, and your employer must tell you how to deliver or send this 

questionnaire to the health care professional who will review it. 

Part A. Section 1. (Mandatory) The following information must be provided by every employee 

who has been selected to use any type of respirator (please print). 

i. Today's date: 

2. Your name: 

3. Your age (to nearest year): 

4. Sex (circle one): Male/Female 

5. Your height: ft. in. 

6. Your weight: lbs. 

7. Your job title: 

8. A phone number where you can be reached by the health care professional who reviews this 

questionnaire (include the Area Code) : 

9. The best time to phone you at this number: 

10. Has your employer told you how to contact the health care professional who will review this 

questionnaire (circle one): Yes/No 

11. Check the type of respirator you will use (you can check more than one category): 

a. __ N, R, or P disposable respirator (filter-mask, non-cartridge type only). 

b. __ Other type (for example, half- or full-facepiece type, powered-air purifying, supplied

air, self-contained breathing apparatus).

C-1 NUREG/CR-0041, Revision I
12. Have you worn a respirator (circle one): Yes/No. 

If "yes" what type(s) 

Part A. Section 2. (Mandatory) Questions I through 9 below must be answered by every employee 

who has been selected to use any type of respirator (please circle "yes" or "no"9). 

1. Do you currently smoke tobacco, or have you smoked tobacco in the last month: Yes/No 

2. Have you ever had any of the following conditions? 

a. Seizures (fits): Yes/No 

b. Diabetes (sugar disease): Yes/No 

c. Allergic reactions that interfere with your breathing: Yes/No 

d. Claustrophobia (fear of closed in places): Yes/No 

e. Trouble smelling odors: Yes/No 

3. Have you ever had any of the following pulmonary or lung problems? 

a. Asbestosis: Yes/No 

b. Asthma: Yes/No 

c. Chronic bronchitis: Yes/No 

d. Emphysema: Yes/No 

e. Pneumonia: Yes/No 

f. Tuberculosis: Yes/No 

g. Silicosis: Yes/No 

h. Pneumothroax (collapsed lung): Yes/No 

i. Lung Cancer: Yes/No 

j. Broken ribs: Yes/No 

k. Any chest injuries or surgeries: Yes/No 

I. Any other lung problem that you've been told about: Yes/No 

4. Do you currently have any of the following symptoms of pulmonary or lung illness? 

a. Shortness of breath: Yes/No 

b. Shortness of breath when walking fast on level ground or walking up a slight hill or incline: 

Yes/No 

c. Shortness of breath when walking with other people at an ordinary pace on level ground: 

Yes/No 

d. Have to stop for breath when walking at your own pace on level ground: Yes/No 

e. Shortness of breath when washing or dressing yourself: Yes/No 

f. Shortness of breath that interferes with your job: Yes/No 

g. Coughing that produces phlegm (thick sputum): Yes/No 

h. Coughing that wakes you early in the morning: Yes/No 

i. Coughing that occurs mostly when you are lying down: Yes/No 

j. Coughing up blood in the last month: Yes/No 

k. Wheezing: Yes/No 

1. Wheezing that interferes with your job: Yes/No 

m. Chest pain when you breathe deeply: Yes/No 

n. Any other symptoms that you think may be related to lung problems: Yes/No

NUREG/CR-0041, Revision I C-2
5. Have you ever had any of the following cardiovascular or heart problems? 

a. Heart attack: Yes/No 

b. Stroke: Yes/No 

c. Angina: Yes/No 

d. Heart failure: Yes/No 

e. Swelling in your legs or feet (not caused by walking): Yes/No 

f. Heart arrhythmia (heart beating irregularly): Yes/No 

g. High blood pressure: Yes/No 

h. Any other heart problem that you've been told about: Yes/No. 

6. Have you ever had any of the following cardiovascular or heart symptoms? 

a. Frequent pain or tightness in your chest: Yes/No 

b. Pain or tightness in your chest during physical activity: Yes/No 

c. Pain or tightness in your chest that interferes with you job: Yes/No 

d. In the past two years, have you noticed your heart skipping or missing a beat: Yes/No 

e. Heartburn or indigestion that is not related to eating: Yes/No 

f. Any other symptoms that you think may be related to heart or circulation problems: Yes/No 

7. Do you currently take medication for any of the following problems? 

a. Breathing or lung problems: Yes/No 

b. Heart trouble: Yes/No 

c. Blood pressure: Yes/No 

d. Seizures (fits): Yes/No 

8. If you've used a respirator, have you ever had any of the following problems? (If you've never used a 

respirator, check the following space and go to question 9: 

a. Eye irritation: Yes/No 

b. Skin allergies or rashes: Yes/No 

c. Anxiety: Yes/No 

d. General weakness or fatigue: Yes/No 

e. Any other problem that interferes with your use of a respirator: Yes/No 

9. Would you like to talk to the health care professional who will review this questionnaire about your 

answers to this questionnaire: Yes/No. 

Questions 10 to 15 below must be answered by every employee who has been selected to use either 

a full-facepiece respirator or a self-contained breathing apparatus (SCBA). For employees who 

have been selected to use other types of respirators, answering these questions is voluntary. 

10. Have you ever lost vision in either eye (temporarily or permanently): Yes/No 

11. Do you currently have any of the following vision problems? 

a. Wear contact lenses: Yes/No 

b. Wear glasses: Yes/No 

c. Color blind: Yes/No 

d. Any other eye or vision problem: Yes/No

C-3 NUREG/CR-0041, Revision I
12. Have you ever had an injury to your ears, including a broken eardrum: Yes/No

13. Do you currently have any of the following hearing problems? 

a. Difficulty hearing: Yes/No 

b. Wear a hearing aid: Yes/No 

c. Any other hearing or ear problem?: Yes/No 

14. Have you ever had a back injury?: Yes/No 

15. Do you currently have any of the following musculoskeletal problems? 

a. Weakness in any of your arms, hands, legs, or feet: Yes/No 

b. Back pain: Yes/No 

c. Difficulty fully moving your arms and legs: Yes/No 

d. Pain or stiffness when you lean forward or backward at the waist: Yes/No 

e. Difficulty fully moving your head up or down: Yes/No 

f. Difficulty fully moving your head side to side: Yes/No 

g. Difficulty bending at your knees: Yes/No 

h. Difficulty squatting to the ground: Yes/No 

i. Climbing a flight of stairs or a ladder carrying more than 25 Ibs: Yes/No 

j. Any other muscle or skeletal problem that interferes with using a respirator: Yes/No 

Part B. Any of the following questions, and other questions not listed, may be added to the 

questionnaire at the discretion of the health care professional who will review the questionnaire. 

1. In your present job, are you working at high altitudes (over 5,000 feet) or in a place that has lower than 

normal amounts of oxygen: Yes/No. If "yes," do you have feelings of dizziness, shortness of breath, 

pounding in your chest, or other symptoms when you're working under these conditions: Yes/No. 

2. At work or at home, have you ever been exposed to hazardous solvents, hazardous airborne chemicals 

(e.g., gases, fumes, or dust), or have you come into skin contact with hazardous chemicals: Yes/No. If 

"yes," name the chemicals if you know them: 

3. Have you ever worked with any of the materials, or under any of the conditions, listed below: 

a. Asbestos: Yes/No 

b. Silica (e.g., in sandblasting): Yes/No 

c. Tungsten/cobalt (e.g., grinding or welding this material): Yes/No 

d. Beryllium: Yes/No 

e. Aluminum: Yes/No 

f. Coal (for example, mining): Yes/No 

g. Iron: Yes/No 

h. Tin: Yes/No 

i. Dusty environments: Yes/No 

j. Any other hazardous exposures: Yes/No If "yes," describe these exposures:

NUREG/CR-0041, Revision I C-4
4. List any second jobs or side businesses you have:

5. List your previous occupations: 

6. List your current and previous hobbies: 

7. Have you been in the military services? Yes/No 

If "yes," were you exposed to biological or chemical agents (either in training or combat): Yes/No 

8. Have you ever worked on a HAZMAT team? Yes/No 

9. Other than medications for breathing and lung problems, heart trouble, blood pressure, and seizures 

mentioned earlier in this questionnaire, are you taking any other medications for any reason (including 

over-the-counter medications): Yes/No. 

If "yes," name the medications if you know them: 

10. Will you be using any of the following items with your respirator(s)? 

a. HEPA Filters: Yes/No 

b. Canisters (for example, gas masks): Yes/No 

c. Cartridges: Yes/No 

11. How often are you expected to use the respirator(s) (circle "yes" or "no" for all answers that apply to 

you)? 

a. Escape only (no rescue): Yes/No 

b. Emergency rescue only: Yes/No 

c. Less than 5 hours per week: Yes/No 

d. Less than 2 hours per day: Yes/No 

e. 2 to 4 hours per day: Yes/No 

f. Over 4 hours per day: Yes/No 

12. During the period you are using the respirator(s), is your work effort: 

a. Light (less than 200 kcal per hour): Yes/No. If "yes," how long does this period last during the 

average shift: _ hrs mins. 

Examples of a light work effort are sitting while writing, typing, drafting, or performing light assembly 

work: or standing while operating a drill press (1-3lbs.) or controlling machines. 

b. Moderate (200 to 350 kcal per hour): Yes/No. If "yes," how long does this period last during the 

average shift: hrs. mins. Examples of a light work 

effort are sitting while nailing or filing; driving a truck or bus in urban traffic; standing while 

drilling, nailing, performing assembly work, or transferring a moderate load (about 35 lbs.) at 

trunk level: walking on a level surface about 2 mph or down a 5-degree grade about 3 mph; or 

pushing a wheelbarrow with a heavy load (about 100 lbs.) on a level surface.

C-5 NUREG/CR-0041, Revision I
c. Heavy (above 350 kcal per hour): Yes/No. If "yes," how long does this period last during the 

average shift: hrs. mins. 

Examples of heavy work are lifting a heavy load (about 50 lbs.) from the floor to your waist or shoulder; 

working on a loading dock; shoveling; standing while bricklaying or chipping castings; walking up an 8

degree grade at about 2 mph; climbing stairs with a heavy load (about 50 lbs.). 

13. Will you be wearing protective clothing and/or equipment (other than the respirator) when you're 

using your respirator: Yes/No If "yes," describe this protective clothing and /or 

equipment: 

14. Will you be working under hot conditions (temperature exceeding 77 'F): Yes/No 

15. Will you be working under humid conditions: Yes/No 

16. Describe the work you'll be doing while you're using your respirator(s): 

17. Describe any special or hazardous conditions you might encounter when you're using your 

respirator(s) (for example, confined spaces, life-threatening gases): 

18. Provide the following information, if you know it, for each toxic substance that you'll be exposed to 

when you're using your respirator(s): Name of the first toxic substance: 

Estimated maximum exposure level per shift: 

Duration of exposure per shift 

Name of the second toxic substance: 

Estimated maximum exposure level per shift: 

Duration of exposure per shift: 

Name of the third toxic substance: 

Estimated maximum exposure level per shift: 

Duration of exposure per shift: 

Name of the fourth toxic substance: 

Estimated maximum exposure level per shift: 

Duration of exposure per shift: 

The name of any other toxic substances that you'll be exposed to while using your 

respirator: 

19. Describe any special responsibilities you'll have while using your respirator(s) that may affect the 

safety and well being of others (for example, rescue, security):

NUREG/CR-0041, Revision 1 C-6
APPENDIX D 

Respirator User Medical Status Form 

Respirator User Medical Status 

(Name of Licensee) 

Name SSN

Date of Screening_______ Screening Administrator

Results of Screening 

"o Approved for use of ALL TYPES of Respirators 

"o NOT Approved for ANY Respirator Use 

oi CONDITIONALLY APPROVED (Complete the section below.) 

Signature of Screening Administrator 

Conditional Approval Supplementary Information 

Describe the limitations on respirator use for this individual: 

Physician's Signature Date 

(Required for conditional approval only.) 

(A form like this could beforwardedfrom the medical department to the RPA to verify 

respirator user status. The confidential medical records can then be maintained in the 

medical department.)

D-1 NUREG/CR-0041, Revision I
APPENDIX E 

The Rainbow Passage 

(Used for the talking exercise during respirator fit testing.) 

The Rainbow Passage 

When the sunlight strikes raindrops in 

the air, they act like a prism and form a 

rainbow. The rainbow is a division of 

white light into many beautiful colors. 

These take the shape of a long round 

arch, with its path high above and its 

two ends apparently beyond the 

horizon. There is, according to legend, 

a boiling pot of gold at one end. 

People look, but no one ever finds it. 

When a man looks for something 

beyond his reach, his friends say that he 

is looking for the pot of gold at the end 

of the rainbow. 

(Repeat for the duration of the exercise.)

E-1 NUREG/CR-0041, Revision 1
14000

0 

13000 '4 

474 .,16 

12000 - Oxygen-Enriched - 9 

:___Breathing Gas Should Be > 

11000 Considered >10,000 ft. 

>10000 " 1000)i 523 10.1 Mr =. 

9000 0O-Deficient IDLH 

8000 0 7000 --- _ 575 11.1 

I 9-" 

.0 

:P6000> S50 ... 02-Deficient 632 12.2 

S4000 -' 

3000 

694 13.4 2000, . ' Not 02-Deficient " 

10000 

0 ~760 .4-.7 

S11 12 13 14 15 16 17 18 19 20 21 

Percent Oxygen 

41

Figure 6-3. Oxygen deficiency and the relationship between percent 02 and elevation (atmospheric pressure), 

after ANSI Z8.2-1992, Table 2.
NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER (2-89) NRCM 1102. (Assigned by NRC, Add Vol., Supp., Rev., 

3201 3202 BIBLIOGRAPHIC DATA SHEET and Addendum Numbers, If any.) 

(See instructions on the reverse) 

2, TITLE AND SUBTITLE NUREG/CR-0041 Revision 1 

Manual of Respiratory Protection Against Airborne Radioactive Material 

3. DATE REPORT PUBLISHED 

MONTH YEAR 

January 2001 

4. FIN OR GRANT NUMBER 

J2660 

5. AUTHOR(S) 6. TYPE OF REPORT 

K. Paul Steinmeyer Technical 

7. PERIOD COVERED (Inclusive Dates) 

8. PERFORMING ORGANIZATION -NAME AND ADDRESS (If NRC, provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address, if contractor, 

provide name and mailing address.) 

Radiation Safety Associates, Inc. 

19 Pendelton Drive, P.O. Box 107 

Hebron, CT 06248

9. •51-'UNSOR(ING ORI(ANIZATION - NAME AND ADDRESS (If NRC, type 'Same as above", if contractor, provide NRC Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address.)

Division of Regulatory Improvement Programs 

Office of Nuclear Reactor Regulation 

U.S. Nuclear Regulatory Commission 

Washinqton, DC 20555-0001

11. ABSTRACT (200 words or less) 

This Manual provides information to assist respirator users and program staff in establishing a respiratory protection program that is in compliance with NRC regulations. It may also be of use to managers, supervisors, engineers and workers who may need to understand respirators, their uses, and their limitations. Chapter 1 provides a brief history of respirator regulations and 

discusses the applicability of OSHA's respiratory protection rules at an NRC-licensed facility. Chapter 2 covers evaluations to 

determine whether or not the use of respirators results in doses that are as low as reasonably achievable, and factoring hazards 

other than radiological hazards into decision making. Chapter 3 addressed respiratory protection procedures and programs, while Chapter 4 gives extensive information on respirators and related equipment including care, use and storage of this 

equipment. Chapter 5 offers advice on user-related issues such as medical evaluation, training and fit testing. Finally, Chapter 

6 supplies information about personnel safety-issues that may be related to respiratory protection, and addressed both 

radiological and non-radiological topics.

12. KEY WORDS/DESCRIPTORS (List words orphrases that will assist researchers in locating the report.) 13. AVAILABILITY STATEMENT 

Respiratory protection unlimited 

14. SECURITY CLASSIFICATION 

(This Page) 

unclassified 

(This Report) 

unclassified 

15. NUMBER OF PAGES 

16. PRICE

NRC FORM 335 (2-89)

V. ou'll- ý 11 1 1ýý I co
Federal Recycling Program
UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, DC 20555-0001 

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PENALTY FOR PRIVATE USE, $300