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Concept for CBRN Full Facepiece Air Purifying Respirator (APR) Standard

DRAFT FOR DISCUSSION

NOTE: This page is archived for historical purposes and is no longer being maintained or updated.

June 15, 2002

(1) Goal:

Develop a NIOSH, NPPTL,tight fitting, full facepiece, air purifying respirator standard that addresses CBRN materials identified as inhalation hazards and/or possible terrorist hazards using a minimum number of filters for emergency responders.

Target: Four (4) filters

  Short Duration Long Duration
TIMs 15 minutes* 60 minutes*
TIMs plus CO 15 minutes* 60 minutes*

* Indicated times are for illustration only.  Actual times will be established from hazard modeling and developmental test results.

(2) Hazards:

NIOSH has been evaluating various lists of chemicals that could be deployed as a result of a terrorist incident.  In an effort to reduce the number of certification tests necessary as part of a Chemical Biological Radiological Nuclear (CBRN) Air-Purifying Respirator (APR) standard, efforts have been underway to categorize potential respiratory hazards into families with a representative test chemical identified for each family.  The following information is a synopsis of this effort to date.

The current carbon technology used in canisters and cartridges were reviewed from existing certification standards. The current standards for gas masks in Europe and the U.S. (NIOSH) were reviewed. The military purchasing specification for ASZM-T carbon for C2A1 military canisters was also reviewed. The most common parameters identified from the review of the military specification and the certification standards were the middle range certification challenges. Some of the test chemicals were considered to be redundant, since other test chemicals would guarantee the carbon effectiveness against the chemicals in question (Chlorine, Hydrogen Chloride, Hydrogen Fluoride, Phosphine, CS & CN Tear Gases).  Carbon tetrachloride and Cyclohexane are the representative chemicals for organic vapors. Meeting the organic vapor test for a cartridge will provide protection for all organic vapors having vapor pressures less than those of carbon tetrachloride and cyclohexane. From the CWA /TIC list, approximately 61 organic chemicals are cover by this logic, including GB and HD. The acid gases (32 chemicals) are covered by cyanogen chloride, hydrogen cyanide, hydrogen sulfide, and sulfur dioxide. Ammonia represents the base gases, and covers another 4 chemicals on the list. Ethylene oxide, formaldehyde, phosgene, phosphine and nitrogen dioxide are considered special case chemicals. Phosphine is a hydride and must be removed catalytically (copper+2 and silver impregnates on carbon). Therefore, 108 of the 151 chemicals can be addressed through testing these 11 chemicals.  Only one organic vapor test agent, cyclohexane or carbon tetrachloride, will be used reducing the list to 10 test chemicals.  Nine of the test chemicals are listed in ITF 25.

Chemicals Organization Using as Test Agent
Ammonia NIOSH & EN
Cyclohexane Organic Vapor- EN
Carbon Tetrachloride Organic Vapor- NIOSH
Cyanogen Chloride Military
Formaldehyde NIOSH
Hydrogen Cyanide NIOSH, EN & Military
Hydrogen Sulfide NIOSH & EN
Nitrogen Dioxide NIOSH & EN
Phosgene Military
Sulfur Dioxide NIOSH & EN
Phosphine NIOSH
Carbon Monoxide NIOSH

Hazard mapping: Conduct modeling based on the 'Most Credible Event' (MCE) scenarios developed for the open-circuit SCBA CBRN standard to determine warm zone operational scenarios. Add or delete scenarios depending on the Toxic Industrial Material (TIM) being evaluated.

(3) Respirator Use:

A. Warm Use: Less than IDLH concentrations, to REL; sustained warm zone support operations; long term use for decon, traffic control, rehabilitation, rescue and recovery; agent known & quantified.

B. Crisis Provision: Contingency use for short duration, above IDLH concentrations and high physiological (flow) demand possible; Contingency for unforeseen factors such as secondary device or pockets of entrapped hazard.

    Long Duration Crisis Short Duration
Filter Configuration Less Than IDLH Panic Demand Less Than IDLH
Filter #1, TIM's less CO Full Facepi.0pt'>Back or Chest Mounted 60 Minutes* 5 Minutes*  
Filter #2, TIM's plus CO Full Facepi.0pt'>Back or Chest Mounted 60 Minutes* 5 Minutes*  
Filter #3, TIM's less CO Full Facepi.0pt'>Mask Mounted   5 Minutes* 15 Minutes*
Filter #4, TIM's plus CO Full Facepi.0pt'>Mask Mounted   5 Minutes* 15 Minutes*

* Indicated times are for illustration only. Actual times will be established from hazard modeling and developmental test results.

(4) Filter Test Requirements:

>Test Matrix for CBRN Air Purifying Respirators; June 12, 2002

Test Order Penetration and Permeation Testing Particulate Testing Service Life Testing,
64 lpm flow
Service Life Testing, high flow 42 CFR
Testing
Drop
 (not order specific)
Human Factors
(not order specific)
Interchangeability
  6 APR systems
(3 - GB and 3 - HD)
60 canister Units 60 canister units 12 canister units TBD APR systems 6 Canister Units 
(2 per test)
APR Systems
--TBD --
(2 APR systems per test)
APR Systems
--TBD --
1. Hot diurnal Hot diurnal Hot diurnal Service Life Testing, 100 LPM Canister in Parallel Resistance Requirements, 84.112 Major axis vertical, air inlet down Hydration (3) EN 136 & EN 148
2. Cold constant Cold constant Cold constant   Breathing Tube, 84.115 Major axis vertical, air inlet up Optical Haze  
3. Humidity Humidity Humidity   Facepieces; eyepieces minimum requirements, 84.119 Major axis horizontal Communications  
4. Transportation vibration Transportation vibration Transportation vibration   Exhalation valve leakage test, 84.123 (2)   Field of View  
5. System testing (GB or HD) Initial breathing resistance, 84.122 Initial breathing resistance, 84.122   Determine CO2 levels (4)   Donning  
6.   DOP Testing, 84.181 Service Life Testing, 64 LPM       Fogging  
7.   Final breathing resistance, 84.122 Final breathing resistance, 84.122       LRPL Testing  

Notes:

1.The six (6) APR systems may be used in the Penetration and Permeation test.

2. RCT-APR-STP-0004, Determination of Exhalation Valve Leakage Test, APR, STP, dated March 7, 2002 for HF Breathing Resistance:  3 Respirators.

3. RCT-APR-STP-0014, Determination of Leakage of Drinking Tube and Accessories for Respirator Facepieces STP, dated January 14, 2002, for HF Hydration/Drinking Tube:  3 Respirators.

4. RCT-APR-STP-0064, Determination of Facepiece Carbon Dioxide and Oxygen Concentration Levels of Tight Fitting Powered Air Purifying Respirators with the Blower Unit Off and Tight Fitting Non-Powered Gas Masks with a Tight Fitting Neck Seal STP, dated April 26, 2001 for HF CO2 Test:  3 Respirators.

  Warm Zone Crisis(1)
  Non IDLH (2) Greater than IDLH (2)
64 lpm flow X  
high flow 100 lpm   X
Rough handling X X

(1) Crisis is a high use concentration at a high flow rate, 100 liters, per minute.

(2) Same test concentrations, different flow rates

(5) Special Test Requirements:

(5)(a)  Chemical Agent Permeation and Penetration Resistance Against Distilled Mustard (HD) and Sarin (GB) Agent Requirement

The air purifying respirator system, including all components and accessories shall resist the permeation and penetration of distilled sulfur mustard (HD) and Sarin (GB) chemical agents when tested on an upper-torso manikin connected to a breathing machine operating at an air flow rate of 40 liters per minute (L/min), 36 respirations per minute, 1.1 liters tidal volume.

Test requirements for distilled sulfur mustard (HD) are shown in Table 1.

Table 1: Simultaneous Liquid and Vapor Challenge of APR with Distilled Sulfur Mustard (HD)

Agent ChallengeConcentration Duration of Challenge (min) Breathing Machine Airflow Rate (L/min) Maximum Peak Excursion  (mg/m3) Maximum Breakthrough (concentration integrated over Minimum Service Life) (mg-min/m3) Number of Systems Tested Minimum Service Life (hours)
HD-Vapor 300 mg/m3 TBD(1)** 40 0.60(3) TBD (4) 3 TBD (2)**
HD-Liquid TBD TBD

** Duration of challenge and minimum service life will be determined from hazard modeling and  developmental test results.

(1) Vapor challenge concentration will start immediately after the liquid drops have been applied and the test chamber has been sealed.

(2) The test period begins upon start of initial vapor generation.

(3) Three consecutive sequential test data points at or exceeding 0.6 mg/m3 will collectively constitute a failure where each test value is based on a detector sample time of approximately 2 minutes.    

(4) The cumulative Ct including all peak data points must not be exceeded for the duration of the test.

Test requirements for Sarin (GB) agent are shown in Table 2.

Table 2: Vapor Challenge of APR with Sarin (GB)

Challenge Agent Vapor Concentration (mg/m3) Vapor Challenge Time (minutes) Breathing Machine Airflow Rate (L/mi Maximum Peak Excursion mg/m3 Maximum Breakthrough (concentration integrated over Minimum Service Life) (mg-min/m3) Number of Systems Tested Minimum Service Life (hours)
GB 2,000 mg/m3 TBD (1)** 40 0.087(3) TBD(4) 3 TBD(2)**

** Duration of challenge and minimum service life will be determined from hazard modeling and developmental test results.

(1) The vapor challenge concentration generation will be initiated immediately after test chamber has been sealed.

(2) The test period begins upon initial generation of vapor concentration.

(3) Three consecutive sequential test data points at or exceeding 0.087 mg/m3 will collectively constitute a failure where each test value is based on a detector sample time of approximately 2 minutes.

(4) The cumulative Ct including all peak data points must not be exceeded for the duration of the test.

(5)(b) Laboratory Respiratory Protection Level (LRPL) Test Requirement:

The measured laboratory respiratory protection level (LRPL) for each full facepiece, air purifying respirator shall be 1000, when the APR facepiece is tested in a negative pressure mode in an atmosphere containing 20-40 mg/m3 corn oil aerosol of a mass median aerodynamic diameter of 0.4 to 0.6 micrometers.

(6) Design Requirements:

(6)(a) Filter Canister Test Challenge and Breakthru Concentrations

 

Test Concentration

Draft

Breakthru Concentration

Draft

Ammonia 2500 12.5
Cyanogen Chloride 300 2
Carbon Tetrachoride 3000 5
Cyclohexane 3900 10
Formaldehyde> 3500 1
Hydrogen Cyanide 940 4.7
Hydrogen Sulfide 1000 5.0
Nitrogen Dioxide 200 1
Phosgene 250 1.25
Phosphine 1500 5
Sulfur Dioxide 1500 5

(6)(a)Interchangeable consumable filter cartridges and canisters

Interchangeable consumable filter cartridges and canisters are not required, as part of CBRN APR certification, but optional approval requirements for manufacturers will be identified.  Interchangeability concept will use existing European standards, EN 136 and EN 148.

(6)(b)Rough handling (transportability, temperature range, survivability)

Test Test Method Test Condition Duration Pass / Fail
Criteria(1)
Hot Diurnal Mil-Std-810F, 501.4 71 0C max, cyclical 3 Weeks Gas Life, System Permeation / Penetration
Cold Constant Mil-Std-810F, 502.4 Basic Cold, -32 0C 3 Days Gas Life, System Permeation / Penetration
Humidity Mil-Std-810E, 507.3 Table 507.3-II, Natural Cycle, Cycle 1

5 Days,

Quick Look

Gas Life, System Permeation / Penetration

Vibration Mil-Std-810F, 514.5 US Highway Vibration, Unrestrained Figure 514.5C-1

12 Hours / Axis, 36 Hours Total

(12,000 miles)

Gas Life, System Permeation / Penetration
Drop 3 foot drop onto concrete Filter Only, 3 Axis N/A Gas Life, System Permeation / Penetration

(1) Pass / Fail Criteria is determined after APR has been subjected to Hot, Cold, Humidity and Vibration environmental exposure sequence order.  Pass / Fail Criteria for Drop test is determined after 3 drops, 1 drop per axis, is completed.

(6)(c) Operational Characteristics (donning, field of view/acuity, flow, resistance, storage life, usage life)

(6)(c)(1) Full Facepiece Fogging

The respirator performance rating for resistance to fogging shall be greater than or equal to 70% when tested in accordance to the fogging test procedure, Appendix A:

(6)(c)(2) Communications

The respirator performance rating for communications shall be greater than or equal to 70% when tested in accordance with the communications test procedure, Appendix B.

(6)(c)(3) Breathing Resistance

Resistance to air flow shall be measured in the facepiece of a CBRN air purifying respirator mounted on a test fixture with air flowing at a continuous rate of 85 liters per minute both before and after each gas service life bench test.  The maximum allowable resistance to air flow is as follows:

  Chin Style Non Facepiece Mounted
Inhalation:    
  Initial  65 mm H2 70 mm H2O
  Final (1)   80 mm H2O 85 mm H2O
Exhalation: 26 mm H2O 26 mm H2O

(1) Measured at end of service life

(6)(c)(4)  Field of View

The full facepiece equipped with a single visor shall be designed so that the effective field of vision shall be not less than 70% related to the natural field of vision, and the overlapped field of vision related to the natural overlapped field of vision, shall not be less than 80%.

A full facepiece equipped with two eyepieces shall be designed so that the effective field of vision shall not be less than 70% related to the natural field of vision, and the overlapped field of vision, shall not be less than 20%.

The field of view test procedure will be developed based on procedures of EN 136.

(6)(c)(5)  Haze (Lens Abrasion)

Specimen CBRN APR facepiece lenses shall be tested for abrasion resistance and the average value of the tested specimens shall not exhibit a delta haze greater than 14%.

The abrasion resistance test procedure will be developed based on NFPA 1981 standard procedures.

(6)(c)(6)  Carbon Dioxide

The maximum allowable average inhaled CO2concentration shall be less than or equal to 2%.

Test procedure RCT-APR-STP-0064 is used for carbon dioxide testing.

(6)(c)(7)  Hydration

For CBRN APR respirators equipped with a hydration facility, the CBRN APR respirator shall meet all requirements of the CBRN APR standard with the hydration facility in place.  In addition, dry drinking tube valves, valve seats, or seals will be subjected to a suction of 75mm water column height while in a normal operating position.  Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute.

Test procedure RCT-APR-STP-0014 shall be used to test the hydration facility for leakage.

(6)(d) Long term field auditing/maintenance procedures/ inspection

(6)(e) Extracts from 42 CFR, Part 84

(6)(e)(1)  42 CFR, Part 84 Subparts A, B, D, E, F and G apply in total:

Subpart A: General Provisions

Subpart B: Application For Approval

Subpart D: Approval and Disapproval

Subpart E: Quality Control

Subpart F: Classification of Approved Respirators

Subpart G: General Construction and Performance

(6)(e)(2)  42 CFR, Part 84 Subpart I; the following paragraphs apply:

84.110 Gas Masks; description.

84.111 Gas masks; required components

84.112 Canisters and cartridges in parallel; resistance requirements

84.113 Canisters and cartridges; color and markings; requirements

84.114 Filters used with canisters and cartridges; location; replacement

84.115 Breathing tubes; minimum requirements

84.116 Harnesses; installation and construction; minimum requirements

84.117 Gas mask containers; minimum requirements

84.118 Half-mask facepieces, full facepieces, and mouthpieces; fit; minimum requirements

84.119 Facepieces; eyepieces; minimum requirements

84.120 Inhalation and exhalation valves; minimum requirements

84.121 Head harnesses; minimum requirements

84.123 Exhalation valve leakage test

Appendix A - Full Facepiece Fogging

Two individuals with a visual acuity of 20/70 better shall perform each test while wearing the apparatus according to manufacturers directions.  Test participants shall be assigned a properly sized and fitted test respirator for each environmental exposure condition.  All participants shall be trained in the donning and usage of the respirator per manufacturer's instructions.

Prior to testing, visual acuity shall be recorded for each subject while wearing the respirator using Snellen Eye Test charts or an equivalent method.

Test 1

The APR shall be cold soaked in an environmental chamber at minus 21oC (-6oF)for 4 hours.

At the start of each cold temperature wear trial a test participant shall enter the test chamber (maintained at -21oC) and sit quietly for five minutes. Once the five minute rest period transpires, subjects shall self-don their assigned respirator.

A visual acuity test shall then be administered to quantify the impact of any lens fogging on vision.

The test participant shall then complete a 12-minute work-rest-work regimen comprised of five minutes of exercise, 2 minutes of rest, and an additional five minutes of exercise with the exercise periods consisting of treadmill walking at 4.8 km/hr (3 mph) on a level grade.

Visual acuity tests shall be repeated at the end of each walk period (i.e., after five minutes of walking and at the end ofTest 2

The APR shall be conditioned in an environmental chamber at 15.5oC (60oF), 75% RH for 4 hours.

At the start of each cool/humid temperature wear trial a test participant shall enter the test chamber (maintained at 15.5 C) and sit quietly for five minutes. Once the five minute rest period transpires, subjects shall self-don their assigned respirator.

A visual acuity test shall then be administered to quantify the impact of any lens fogging on vision.

The test participant shall then complete a 12-minute work-rest-work regimen comprised of five minutes of exercise, 2 minutes of rest, and an additional five minutes of exercise with the exercise periods consisting of treadmill walking at 4.8 km/hr (3 mph) on a level grade.

Visual acuity tests shall be repeated at the end of each walk period.

Visual acuity scores obtained during each environmental test with the respirator shall be divided by a subject's visual acuity score obtained with the mask prior to testing to calculate a performance rating using the following equation:

Performance Rating (%) = VACHAMBEREX / VAINITIAL X 100  (1) 

where VAchamber x = visual acuity score during chamber test at time x and VAintial = visual acuity score obtained with the mask prior to testing.Visual acuity performance ratings calculated from measurements taken post-donning and at the end of each treadmill walk shall be averaged for each individual subject to obtain an average visual acuity performance rating for each subject based on the environmental condition.Average performance rating for each test participant shall be greater than or equal to 70% for both Test 1 and Test 2 to meet the fogging requirement.

Appendix B-Communication

1) Speech intelligibility testing shall be accomplished through the use of the Modified Rhyme Test (MRT), which evaluates a listener's ability to comprehend single words and provides an indication of speech transmission of the selected words.  The MRT consists of multiple lists of 50 monosyllabic, phonetically balanced words each.  A sample word list is provided in Table 1.Table 1.  Sample MRT stimulus word list

1. lick 11. same 21. pad 31. pip 41. name
2. beat 12. peal 22. din 32. seen 42. soil
3. puff 13. kit 23. sit 33. way 43. fin
4. cook 14. sat 24. win 34. west 44 cuff
5. tip 15. sin 25. teak 35. pace 45. heal
6. rave 16. gold 26. dent 36. bat 46. hark
7. hang 17. buff 27. sub 37. mop 47. heat
8. till 18. lay 28. led 38. big 48. then
9. math 19. nun 29. tot 39. tab 49. law
10. sale 20. must 30. dub 40. case 50. bean

2) Three test listeners consisting of two males and one female shall comprise the subject test panel.  All participants shall be tested for "normal" hearing prior to testing by a qualified individual.

3) An additional five individuals (four males and one female) without obvious speech defects or strong regional accents shall serve as MRT speakers.

4) All participants shall be trained in the donning and usage of the respirator per manufacturer's instructions and all shall pass a qualitative facepiece-to-face fit check according to the manufacturer's instructions.

5) Procedure:

a.The three test listeners shall be seated opposite a single test speaker for each MRT trial at a distance of 3 meters (10 ft), and they shall be facing one another.  Each listener shall be given a multiple choice answer sheet or positioned before a computer and monitor that will be used to input his or her responses.

b. Data for the MRT will be collected with a steady background noise of 60 dBA consisting of a broadband "pink" noise.  A Brüel and Kjaer Type 1405 Noise Generator or equivalent will be used to produce the background noise.  Background noise levels will be monitored at a position near the listening panel using a Type 2 digital sound level meter and recorded at the beginning, middle, and end of each MRT session.

c. The test speaker shall present each stimulus word using the carrier phrase "The word is _______." 

d. Speakers will be instructed and trained to maintain a constant output volume at 75 dBA to 85 dBA for all presented words.  A Type 2 digital sound level meter will be positioned in front of the speaker within his or her sight to provide feedback concerning the loudness of their voice during testing. Speaker output levels will be recorded at the beginning, middle, and end of each MRT session for verification.

e. Listeners will select the word that was perceived to be spoken from a list of six response words presented on the computer monitor by clicking a button on the monitor that corresponds to the perceived word. If given a paper answer form, subjects will circle their selection. A sample answer sheet is provided in Figure 1.

f. Test listeners shall then provide a thumbs-up hand signal to the speaker to cue him or her to say the next word.

g. An individual speaker will present a total of 50 stimulus words to complete one MRT trial. A different speaker shall then be used to present the next MRT trial. Test speakers will continue to rotate among the speaker test panel until all trials have been complete. A sample test matrix is provided in Table 2.

h. Data will be obtained without the respirator and with the respirator worn and operated per the manufacturer's instructions by both speakers and listeners. All conditions shall be randomly assigned and a different word list shall be used for each test. Again, an example of a test matrix is provided in Table 2.

Table 2. Sample MRT test matrix

Speaker Speaker Condition Listeners' Condition Word list
1 No mask No mask 1
2 No mask No mask 3
3 Masked Masked 5
4 Masked Masked 7
5 No mask No mask 9
2 Masked Masked 2
4 No mask No mask 4
1 Masked Masked 6
5 Masked Masked 8
3 No mask No mask 10

i. A total of 10 MRT trials shall be performed. The 10 trials will result in a total of 15 MRT scores (five per listener) for the unworn mask condition and 15 scores for the worn condition.

j. Listener performance on the MRT shall be scored in terms of the percentage of words correctly identified using the equation:

% correct = (number correct - (number incorrect/5)) * 2

(1)The equation accounts for chance or guessing made possible by the multiple-choice form of the answer sheet (Human Engineering Guide to Equipment Design, American Institutes for Research, Washington, DC, 1972).

k. Individual listeners' scores for the unworn and worn respirator conditions shall be averaged for each condition. 

l. Each individual listener's average score with the respirator shall be divided by their average unmasked MRT score to calculate a performance rating (ref equation (2)).  (Because the listening subjects serve as their own controls, the performance rating allows the effect of the respirator condition to be isolated from the effect of the individual).

    formula   (2)

m. The communications requirement shall be met if the average performance rating is greater than or equal to 70%.

MRT listener Response Sheet
 
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