CBRN Respirator Approval Resources
NIOSH approves respirators that protect against chemical, biological, radiological, and nuclear (CBRN) hazards. Respirators with CBRN protections can include:
- Self-contained breathing apparatus (SCBAs)
- Air-purifying respirators (APRs)
- Air-purifying escape respirators (APERs)
- Powered air-purifying respirators (PAPRs) [NIOSH 2019]
NIOSH published the first CBRN standard in 2001, and has since developed performance and design standards, as well as over 60 Standard Testing Procedures, used to evaluate these types of respirators. The NIOSH Respirator Approval Program has issued close to 400 active approvals for respirators with CBRN protections, which emergency responders use.
Refer to the NIOSH resources below to help properly select, use, and maintain CBRN respirators.
NIOSH CBRN Respiratory Protection Handbook
The NIOSH Chemical, Biological, Radiological, and Nuclear (CBRN) Respiratory Protection Handbook provides information to assist emergency responders on selection, use, and maintenance of CBRN respirators. It also provides information to those individuals responsible for managing respirator protection programs or developing training programs.
NIOSH CBRN APR Protection List
As part of a NIOSH-approved CBRN APR, the CBRN canister provides protection against many CBRN hazards that may be present in an emergency event. These hazards are collectively represented in the NIOSH CBRN APR Protection List [NIOSH 2005, NIOSH 2018]. This list was developed through a comprehensive review of technical data and the evaluation of various lists of chemicals that could be used in a terrorist incident [NIOSH 2018]. NIOSH uses this list to categorize CBRN hazards into seven different chemical families and uses 11 chemicals—known as test representative agents—to test the protective ability of a canister claiming CBRN protections. In 2001, NIOSH’s hazard assessment concluded with 139 hazards identified across these seven chemical families [NIOSH 2005, NIOSH 2018]. In a more recent assessment completed in 2018, this list has been expanded to 286 hazards. NIOSH found that its test representative agents remain sufficient to evaluate protections against the additional chemical hazards—some new or emerging—identified during the recent hazard assessment.
- Cloonan, T.K., Palya, F., Stein, R. Coffey, C.C. Wizner, K.L., Greenawald, L., Szalajda, J.V. (2018). Respiratory Protection for Emergency Responders Handbook of Respiratory Protection: Safeguarding Against Current and Emerging Hazards (429-451). FL: CRC Press.
CBRN APR Protection List
During the development of the NIOSH CBRN APR Statement of Standard in the early 2000s, NIOSH and its federal partners, including the Department of Defense (DoD), Department of Justice, and Department of Energy, conducted a hazard assessment with a goal to list all potential CBRN hazards that may pose a risk to emergency responders and are likely to be used in a disaster. This hazard assessment consisted of a comprehensive review of technical data and the evaluation of various lists of chemicals that could be used in a terrorist incident [NIOSH 2018]. Further, physical and chemical properties (including filtration mechanisms) were evaluated. The final list included 139 CBRN hazards. NIOSH then worked on developing minimum performance requirements to ensure that NIOSH-approved CBRN respirators would provide protection against these hazards [NIOSH 2018].
To do so, NIOSH further categorized the 139 hazards into seven chemical families,1 characterized by common chemical properties and filtration behavior [NIOSH 2018]. As part of its Respirator Approval Program evaluation of APRs, APERs, and PAPRs, NIOSH used 11 of these chemicals as representatives from the seven NIOSH chemical families, referring to them as test representative agents.2
1 NIOSH’s seven CBRN Chemical Families include Organic Vapor, Acid Gas, Base Gas, Nitrogen Oxide, Hydride, Formaldehyde, and the Particulate Family.
2 NIOSH’s 11 CBRN test representative agents include cyclohexane, sulfur dioxide, hydrogen cyanide, phosgene, hydrogen sulfide, cyanogen chloride, ammonia, dioctyl phthalate, nitrogen dioxide, formaldehyde, and phosphine.
In 2018, NIOSH and its Partners Evaluated New and Emerging CBRN Hazards
NIOSH must continue to ensure that the test representative agents used to evaluate CBRN APR canisters represent current or potential hazards, which are always evolving. From 2016 – 2018, NIOSH partnered with the DoD and the Department of Homeland Security (DHS) to identify and evaluate new/emerging chemical and radiological respiratory hazards that may pose a risk to emergency responders. The project team included several individuals present during the initial 2001 hazard assessment.
NIOSH and its partners first identified and compiled hazards by reviewing various hazard assessments available to the DHS. The group then developed a four-step evaluation process to assess each hazard (Fig. 1) which included:
- evaluating its chemical and physical properties,
- evaluating its actual or anticipated filtration behavior within the CBRN canister (i.e., physical adsorption, chemisorption, or mechanical filtration),
- categorizing it into one of NIOSH’s Chemical Families, and
- comparing it against the existing test representative agents in its respective Chemical Family to determine the need for additional test agents.
Figure 1: Summary of the process NIOSH and its partners took to assess new/emerging CBRN hazards [Greenawald et al. 2020]. TRA = test representative agent.
During the hazard assessment, a total of 238 hazards (192 chemicals and 46 radiologicals) were identified [Greenawald et al. 2020]. Of the 238 hazards, 203 could be grouped into one of the existing seven NIOSH Chemical Families. A total of 35 hazards could not be initially categorized: 29 hazards were too unstable in the emergency responder operational environment (e.g., decompose quickly) and six needed further testing and evaluation to confirm their categorization into a NIOSH Chemical Family. For the six that underwent additional testing, NIOSH ultimately determined that it was appropriate to categorize these six hazards within the existing seven NIOSH Chemical Families [Greenawald et al. 2020].
NIOSH Expanded its CBRN APR Protection List – No Changes Were Needed to NIOSH’s CBRN Statements of Standard
After reviewing each of these 238 hazards, the key finding of this effort was that the current 11 CBRN test representative agents continued to represent the known CBRN hazards and should remain the basis for NIOSH respirator approval testing for respirators claiming protections against CBRN hazards. Thus, no changes were needed to NIOSH’s original 11 CBRN test representative agents or NIOSH’s CBRN APR, APER, or PAPR Statements of Standard. However, because of the described evaluation, NIOSH has expanded its original CBRN APR Protection List of 139 hazards to include those additional hazards identified—i.e., NIOSH’s CBRN APR Protection List is now comprised of a total of 286 hazards. Table 1 shows a comparison between the original and updated lists. The NIOSH CBRN test representative agents and list of hazards in each NIOSH Chemical Family, constituting NIOSH’s updated CBRN APR Protection List, is below.
Note: The updated CBRN APR Protection List supersedes the list in NIOSH’s CBRN Respiratory Protection Handbook (Report version 2018-166) and the list in NIOSH’s 2005 interim guidance for CBRN APRs [NIOSH 2005]. This Handbook is being updated.
Table 1: Summary of the original and updated NIOSH CBRN APR Protection List. TRA=test representative agent.
|NIOSH Chemical Family (TRA)||2001 CBRN APR Protection List||Updated NIOSH CBRN APR List|
|Organic Vapor (cyclohexane)||61||109|
|Acid Gas (hydrogen cyanide, hydrogen sulfide, phosgene, cyanogen chloride)||32||48|
|Base Gas (ammonia)||4||4|
|Nitrogen Oxide (nitrogen dioxide)||5||6|
|Particulate, Chemical (dioctyl phthalate)||3||56|
|Particulate, Radiological/Nuclear (dioctyl phthalate)||16||45|
|Particulate, Biological (dioctyl phthalate)||13||133|
3 Biologicals were not evaluated during this 2018 CBRN hazard assessment.
Lee A. Greenawald, Christopher J. Karwacki, Frank Palya, Matthew A. Browe, David Bradley & Jonathan V. Szalajda  Conducting an evaluation of CBRN canister protection capabilities against emerging chemical and radiological hazards, Journal of Occupational and Environmental Hygiene, 17:10, 480-494, DOI: 10.1080/15459624.2020.1798452
NIOSH . NIOSH Interim Guidance on the Use of Chemical, Biological, Radiological, and Nuclear (CBRN) Full Facepiece, Air-Purifying Respirators/Gas Masks Certified Under 42 CFR Part 84. Accessed 08/30/2021.
NIOSH . Chemical, Biological, Radiological, and Nuclear (CBRN) Respiratory Protection Handbook. By Janssen L, Johnson AT, Johnson JS, Mansdorf SZ, Medici OR, Metzler RW, Rehak TR, Szalajda JV. Pittsburgh, PA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2018-166, .
NIOSH . Respirator Standards. Accessed 08/30/2021.
NIOSH’s Updated CBRN APR Canister Protection List
As part of a NIOSH-approved CBRN APR, the CBRN canister provides protection against a minimum of 286 identified CBRN hazards, which are classified into seven chemical families: Organic Vapors (109), Acid Gases (48), Base Gases (4), Hydrides (4), Nitrogen Oxides (6), Particulates (114) [comprised of 56 chemical, 13 biological, and 45 radiological and nuclear particulate threats], and Formaldehyde (1). Actual CBRN incident responses may lead to adjustments to this canister protection listing. The service life of a CBRN canister depends upon many factors including environmental conditions (e.g., temperature, percent relative humidity), breathing rate, filtering capacity, and the type and concentration of contaminants in the air. Filtering capacity is based on many product-specific criteria. It is important that you follow the manufacturer’s guidance and consult your respiratory protection program administrator for additional guidance on determining change-out schedules.
The test representative agents used by NIOSH for approval testing are listed. Those hazards identified during the 2018 hazard assessment are designated with asterisks (*).
NIOSH Organic Vapors Family (109 hazards)
1 TRA chemical (Cyclohexane) is used for certification testing to represent the Organic Vapor Family.
|Acetylene tetrabromide*||Ethyl chloroacetate*||Phosgene oximedichloroforoxime|
|Acrylonitrile||Ethyl chloroformate||Phosphorus oxychloride|
|Allyl alcohol||Ethyl dichloroarsine*||Phosphamidon*|
|Allyl chlorocarbonate||Ethyl phosphonothioicdichloride||Propionitrile*|
|bis-Chloromethyl ether*||Ethylene oxide*||Sec-butyl chloroformate|
|Bromomethane (methyl bromide)*||Hexachlorocyclopentadiene||Tabun|
|Carbon disulfide*||Hexaethyl tetraphosphate||Tert-octyl mercaptan|
|Chloroacetonitrile||Iso-butyl chloroformate||Tetraethyl dithiopyrophosphate|
|Chloroacetophenone||Iso-propyl chloroformate||Tetraethyl pyrophosphate*|
|Chloromethyl methyl ether*||Malathion*||Trimethylacetyl chloride|
|Chloropivaloyl chloride||Methanesulfonyl chloride||1,1,2,2-Tetrachloroethane*|
|Chlorosarin*||Methyl orthosilicate||3-(Triethoxysilyl)propyl isocyanate*|
|Chlorosoman*||Methyl parathion||VM (EDEMO)*|
|Cyclohexyl methyphosphonate||Methyl fluoroacetate*||VG (Amiton)*|
“*” = added because of the 2018 CBRN Hazard Assessment
|Cyclosarin*||Methyl vinyl ketone*|
|Dicrotophos*||Mustard, lewisite mixture|
|Dimethyl mercury*||Nitrogen Mustard (HN-1, HN-2, HN-3)|
|Dimethyl sulfate||O-chlorobenzylidene malononitrile|
|Diphenylcyanoarsine||Octamethyl pyrophosphoramide (OMPA)*|
|Distilled mustard (sulfur mustard; HD)||Perchloromethyl mercaptan|
NIOSH Acid Gas Family (48 hazards)
5 TRA chemicals are used for NIOSH certification testing to represent the Acid Gas Family.
|Boron tribromide||Hydrogen selenide|
|Boron trichloride||Hydrogen sulfide|
|Boron trifluoride||Iodine (131/133)*¥|
|Bromine chloride||Methanesulfonyl fluoride*|
|Bromine pentafluoride||Methanethiol (methyl mercaptan)*|
|Bromine triflouride||Methyl iodide (133/131)*¥|
|Carbonyl fluoride||Methyl isocyanate*|
|Chlorine||Methylphosphonic difluoride (DF)*|
|Chlorine pentafluoride||Pentacarbonyl iron*|
|Chlorine dioxide*||Phosphorous trichloride|
|Cyanogen chloride||Silicon tetrafluoride|
|Cyclohexyl isocyanate*||Sulfur dioxide|
|Ethyl chloroformate*||Sulfuric acid|
|Ethyl isocyanate*||Sulfyryl chloride|
|Ethyl phosphonous dichloride||Titanium tetrachloride|
|Hydrogen bromide||Thionyl chloride*|
|Hydrogen fluoride||“*” = added because of the 2018 CBRN Hazard
Assessment; ¥ = Radiological vapor
Particulate Family Canister Protections (114 hazards)
|1 TRA chemical (dioctyl phthalate/DOP) is used for certification testing to represent the Particulate Family.|
|Particulate Family Canister Protections (56 hazards)|
|4-t-Butyl bicylcophosphate*||Diacetylmorphine*||Phosgene oxime*|
|Aluminum phosphide*||Fentanyl*||Sodium azide|
|Ammonium metavanadate*||Fluoroacetamide*||Sodium fluoride*|
|Arsenic Trioxide*||Malononitrile*||Sodium selenate*|
|3-Quinuclidinyl benzilate (BZ) *||N-ethylmaleimide*||Vanadium pentoxide*|
|Cadmium oxide*||Osmium tetroxide*||Ziram*|
|Particulate-Biological (13 hazards)|
|Anthrax||Venezuelan equine encephalitis|
|Smallpox||Query (Q) Fever|
|T-2 Mycotoxins||Viral hemorrhagic fevers|
|Staphylococcus enterotoxin B|
|Particulate – Radiological/Nuclear (45 hazards)|
|Americium (Am 241, 242*)||Mercury (Hg 197, 194)*|
|Antimony (Sb 124)*||Neptunium (Np 239)*|
|Argon (Ar-41)*||Nickel (Ni 63)|
|Berkelium (Bk 249)*||Phosphorous (P 32)|
|Calcium (Ca 47)*||Plutonium (Pu 238*, 239)|
|Californium (Cf 252)*||Polonium (Po 210)*|
|Carbon (C 14)||Promethium (Pr 147)|
|Cesium (Ce 137)||Radium (Ra 226)|
|Chromium (Cr 51)*||Samarium (Sm 153)*|
|Cobalt (Co 60, 58*, 57*)||Scandium (Sc 48)*|
|Copper (Cu 64)*||Selenium (Se 75)*|
|Gadolinium (Gd 148)*||Silver (Ag 110)*|
|Gallium (Ga 67)*||Sodium (Na 24)*|
|Gold (Au 198)*||Strontium (Sr 85*, 90)|
|Indium (In 111, 114)*||Sulfur (S 35)*|
|Iodine (Io 131, 133*)||Technetium (Te 99)|
|Iridium (Ir 192)*||Thallium (Tl 202*, 204)|
|Iron (Fe 55)*||Thorium (Th 232)|
|Hydrogen (H 3)||Uranium (Ur 235, 238)|
|Krypton (Kr 85)*||Ytterbium (Yb 169)*|
|Lanthanum (La 140)*||Yttrium (Y 88, 90)*|
|Manganese (Mn 53)*||Zinc (Zn 65)*|
NIOSH Hydride Family (4 hazards)
1 TRA chemical (Phosphine) is used for certification testing to represent the Hydride Family.
NIOSH Formaldehyde Family (1 hazard)
1 TRA chemical (Formaldehyde) is used for certification testing to represent the Formaldehyde Family.
NIOSH Basic Gas Family (4 hazards)
1 TRA chemical (Ammonia) is used for NIOSH certification testing to represent the Base Gas Family.
Dimethyl hydrazine, 1,2
NIOSH Nitrogen Oxide Family (6 hazards)
|1 TRA chemical (nitrogen dioxide) is used for NIOSH certification testing to represent the Nitrogen Oxide Family|
Nitric acid, fuming
Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention.