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NIOSH air filtration rating

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A filtering facepiece N95 respirator

The NIOSH air filtration rating is the U.S. National Institute for Occupational Safety and Health (NIOSH)'s classification of filtering respirators. The ratings describe the ability of the device to protect the wearer from solid and liquid particulates in the air. The certification and approval process for respiratory protective devices is governed by Part 84 of Title 42 of the Code of Federal Regulations (42 CFR 84).[1] Respiratory protective devices so classified include air-purifying respirators (APR) such as filtering facepiece respirators and chemical protective cartridges that have incorporated particulate filter elements.

The NIOSH-provided classifications only cover the filtration of particles or aerosols, not the air-purifying respirator's ability to remove chemical gasses and vapors from air, which is regulated under 42 CFR 84 Subpart L. For chemical classifications, NIOSH, under 42 CFR 84, partially defers to American National Standard ANSI K13.1-1973, and others, for matters such as chemical cartridge color classification.[1] All classifications assume that the respirator is properly fitted.[2]

It is illegal in the United States to use filtration terms coined under 42 CFR 84, or mark masks with the word 'NIOSH' without the approval of NIOSH. Information about approved respirators can be found in the NIOSH certified equipment list (CEL).[3]

Early NIOSH/USBM classifications[edit]

Early Standards[edit]

Prior to the 1970s, respirator standards were under the purview of the US Bureau of Mines (USBM). An example of an early respirator standard, Type A, established in 1926, was intended to protect against mechanically generated dusts produced in mines. These standards were intended to obviate miner deaths, noted to have reached 3,243 by 1907. However, prior to the Hawks Nest Tunnel Disaster, these standards were merely advisory, as the USBM had no enforcement power at the time.[4] After the disaster, an explicit approval program was established in 1934, along with the introduction of combination Type A/B/C respirator ratings, corresponding to Dusts/Fumes/Mists respectively, with Type D blocking all three.[5]

The Federal Coal Mine Health and Safety Act establishing MESA (later MSHA),[6] the Occupational Safety and Health Act of 1970, establishing NIOSH,[7] as well as other regulations established around the time, reshuffled regulatory authority for respirators, but nonetheless continued the use of USBM-era regulations.[5]

30 CFR 11[edit]

Example Part 11 'HEPA' Label, TC-21C particulate, with approval for dusts, fumes, mists, radionuclides, and asbestos
3M 6200 with magenta 'Dust-Fume-Mist Radionuclides Asbestos' (30 CFR HEPA) markings on the filters

Prior to the approval of 42 CFR Part 84, MSHA and NIOSH approved respirators under 30 CFR Part 11. Non-powered respirator filters were classified based on their design against a contaminant, including substances like 'dusts', 'fumes', 'mists', radionuclides, and asbestos. 'Dust/Mist' was usually tested with silica, and 'fume' was usually tested with lead fume. The most popular respirator filters were often referred to as 'DM' (dust/mist) or 'DFM' (dust/fume/mist) in CDC and NIOSH literature as shorthand.[8] Non-powered filters were also classified under the HEPA specification, if applicable.[9]

Only 30 CFR 11 HEPA filters were permitted by NIOSH for the prevention of tuberculosis.[10]

NIOSH was concerned about users choosing inappropriate respirators, like confusion over choosing 'dust/mist' or 'dust/fume/mist' respirators with regards to particle penetration, so proposed Part 84 rules in 1994 dropped the contaminant/HEPA classification for most respirators in favor of three specifications, Type A, B and C, each representing filtration of 99.97%, 99%, and 95% respectively, with Type A proposed to be used in place of HEPA for non-powered respirators.[11][9]

(OBSOLETE) 30 CFR Part 11 Efficiency Levels[9]
Particulate Respirator

Approval

Maximum

Dust Penetration

Minimum

Efficiency Level

Permitted for

TB

158.4 mg silica Single-use Dust/Mist Filters 1.8 mg 98.86% No
158.4 mg, usually silica Replaceable Dust/Mist Filters 1.5 mg 99.05% No
0.3 micron DOP HEPA (usually also includes

Dust/Mist approval)

N/A 99.97% Yes

Transition[edit]

Historically, respirators in the US had generally been approved by MESA/MSHA/NIOSH under federal regulation 30 CFR Part 11. On July 10, 1995, in response to respirators exhibiting "low initial efficiency levels," new 42 CFR Part 84 standards, including the N95 standard, were enforced under a three-year transition period,[12] ending on July 1, 1998. The standard for N95 respirators includes, but is not limited to, a filtration of at least 95% under a 200 milligram test load of sodium chloride. Standards and specifications are also subject to change.[13]

Once 42 CFR Part 84 was in effect, MSHA, under a proposed rule change to 30 CFR 11, 70, and 71, would withdraw from the approval process of rated respirators (outside of respirators used for mining).[14]

Current classifications[edit]

42 CFR 84[edit]

Example Part 84 Label, TC-84A particulate, with older NIOSH logo, for P100 respirator, equivalent to Part 11 HEPA
People wearing 3M 2091 Magenta P100 filters. Note that these filters do not block vapors

Under the current revision of Part 84 established in 1995, NIOSH established nine classifications of approved particulate filtering respirators based on a combination of the respirator series and efficiency level. The first part of the filter's classification indicates the series using the letters N, R, or P to indicate the filter's resistance to filtration efficiency degradation when exposed to oil-based or oil-like aerosols (e.g., lubricants, cutting fluids, glycerine, etc.).[1][15][16] Definitions and intended use for each series is indicated below.[17]

  • N for not resistant to oil. Used when oil particulates are not present. Tested using sodium chloride particles.
  • R for resistant to oil. Used when oil particulates are present and the filter is disposed of after one shift. Tested using dioctyl phthalate (DOP) oil particles.
  • P for oil-proof. Used when oil particulates are present and the filter is re-used for more than one shift. Tested with DOP oil particles.

The second value indicates the minimum efficiency level of the filter. When tested according to the protocol established by NIOSH each filter classification must demonstrate the minimum efficiency level indicated below.

NIOSH Particulate Respirator Class Minimum Efficiency Levels[1]
Particulate Respirator

Class

Minimum

Efficiency Level

Permitted for TB
NaCl (N) or DOP (R,P) N95, R95, P95 95% Yes
N99, R99, P99 99%
N100, R100, P100, HE 99.97%

All respirator types are permitted for TB.[18][11] Class-100 filters can block asbestos.[19] For N type filters, a 200 mg load of NaCl is used, with and undefined service time. For R type filters, a 200 mg of DOP is used, with a defined service time of "one work shift". For P type filters, an indefinite amount of DOP is used until filtration efficiency stabilizes.[20] P100 filters, under 42 CFR part 84, are the only filters permitted to be magenta in color.[21] HE (high-efficiency) labeled filters are only provided for powered air-purifying respirators. HE-marked filters are 99.97% efficient against 0.3 micron particles and are oil-proof.[22][23][24]

Since filters are tested against the by definition most penetrating particle size of 0.3 μm, an APR with a P100 classification would be at least 99.97% efficient at removing particles of this size.[16] Particles with a size both less than and greater than 0.3 μm may be filtered at an efficiency greater than 99.97%.[25][26] However, this may not always be the case, as the most penetrating particle size for N95s was measured to be below 0.1 μm, as opposed to the predicted size of between 0.1 and 0.3 μm.[27]

Chemical Cartridge Classifications[edit]

Half-face air-purifying respirator with combination P100 particulate filter (magenta) and organic vapor (black) cartridge

42 CFR 84 Subsection L describes seven types of chemical cartridge respirators with maximum use concentrations and penetration, noting that colors and markings are definitively based off of ANSI K13.1-1973.[1] A TB guide, published by NIOSH in 1999, describes 13 combinations of contaminants with unique color markings.[18] The definitive guide from ANSI, who, since the passage of 42 CFR 84 in 1995, has published a 2001 revision of K13.1-1973, named Z88.7-2001, describes 14 combinations of contaminants with unique color markings, based on 13 out of the 28 NIOSH Protection Designations.[28][29] The ANSI standard also notes that these classifications do not apply in aviation or military respirators.[29]

A comparison table below details the NIOSH protection designations,[28] 42 CFR 84,[1] the Navy/Marine Field Manual,[30] the NIOSH TB guide,[18] and whether they match up with the groups of NIOSH protection designations, per color, in the 42 CFR 84-declared ANSI K13.1-1973 revision ANSI Z88.7-2001,[29] for each type of chemical cartridge is described below. Note that, while the 2001 revision to ANSI K13.1-1973 provides exact colors under the Munsell Color System,[29] colors and combinations outside the public domain, as well as cartridge/canister designation, have been omitted to facilitate this fair use comparison:

Respirator/Filter Type Designation and Color Comparison[a]
NIOSH Protection

Designations[28]

NIOSH Protection

Abbreviation[28]

42 CFR 84 Max Use Concentration[1][a] Penetration Allowed by 42 CFR 84[a] Efficiency Level[a] 1999 NIOSH TB Guide

Color[18]

Correlated with Z88.7-2001

(K13.1-1973 revision)?[29]

Acid gas (gas mask only)[28] AG
N/A
White Yes, for canisters only
Ammonia AM 300 ppm 50 ppm 83.3% Green Yes
Chlorine dioxide CD
N/A
In standard as combination
Chlorine CL 10 ppm 5 ppm 50% White with

1/2" yellow stripe

No stripe, within designation color, but actual color for unlisted combinations
Chloroacetophenone CN
N/A
Carbon monoxide CO
N/A
Blue Yes
Chlorobenzylidene malononitrile CS
N/A
Ethylene oxide EO
Formaldehyde FM
Hydrogen chloride HC 50 ppm 5 ppm 90%
N/A
In standard as combination
Hydrogen fluoride HF
N/A
In standard as combination
Hydrogen cyanide HN
N/A
White, with 1/2" green stripe No stripe, wrong color, actual color for unlisted combinations
Hydrogen sulfide HS
N/A
In standard as combination

(escape only)

Methylamine MA 100 ppm 10 ppm 90%
N/A
In standard with ammonia
Mercury vapor MV
N/A
Nitrogen dioxide ND
Organic Vapor OV 1000 ppm

or lower

5 ppm Depends Black Yes
Phosphine PH
N/A
Sulfur dioxide SD 50 ppm 5 ppm 90%
N/A
In standard as combination
Vinyl chloride VC 10 ppm 1 ppm 90%
N/A
NIOSH designation does not exist, may use unlisted combination color
Toluene diisocyanate TDI
N/A
Demand (SCBA) DE
Non-air-purifying respirators (Atmosphere-Supplying respirators)
Pressure Demand

(SCBA)

PD
Supplied-air (Air-line) SA
Supplied-air Abrasive Blast SB
Self-Contained

(SCBA)

SC
Escape (SCBA) ESC
Respirator Combination Designation and Color Comparison[a]
NIOSH Protection

Abbreviation[28]

Color Correlated with Z88.7-2001

(K13.1-1973 revision)?[29]

1999 NIOSH TB Guide Combinations[18] Any of above

chemicals/ Particulates

Gray stripe Wrong color, no stripe
HN/Chloropicrin Yellow with 1/2" blue stripe NIOSH designation does not exist, no stripe, wrong color, actual color for unlisted combinations
Radionuclides Purple/Magenta Yes, under 30 CFR 11 'HEPA'
AG/HN/CL/OV/AM/CO/

Chloropicrin/ radionuclides/ particulate

Red with

1/2" gray stripe

No stripe needed, combination more than required for color (AG/OV/AM/CO)
AG/AM Green with 1/2" white stripe No stripe, wrong color, actual color for unlisted combinations
AG/OV Yellow Yes, for canisters only
AG/OV/AM Brown Yes, for canisters only
Navy/Marine Field Manual Combinations[30][b] "Acid Gases":

CL/CD/HS/HC/SD/HF

White Combination more than required for color (CL/HC/SD)
"Organic Vapors":

Xylene/Toluene

Brown Within designation color, but wrong color if exclusive
"Basic gases": AM/MA Green Yes
FM Tan Within designation color, but actual color for unlisted combinations
MV Orange NIOSH designation does not exist, wrong color, actual color for unlisted combinations
HEPA Purple Yes
  1. ^ a b c d e See the NIOSH pocket guide for additional respirator use guidelines.
  2. ^ For brevity, only combinations that are different from the TB guide are listed.
Person wearing purple 3M 7093 P100 cartridge filters

For particulate respirators, while NIOSH designates P100 as filter cartridges that can use the "magenta" color, ANSI designates P100 as "purple", a color which can be seen on some P100 filter cartridges. In addition, the 2001 revision to ANSI K13.1-1973 provides exclusive colors to be used for non-P100 cartridge filters, in two categories: oil-resistant (remaining R- and P- NIOSH ratings), and non-oil resistant (all N-ratings).[29]

Table of TC/BM Approval Schedules[edit]

NIOSH is the current regulator of all the respirators in this schedule, under 42 CFR Part 84.[11]

'BM' stands for the US Bureau of Mines, the historical regulator of respirators in the United States.

Approval Schedules[30][31]
US Code Gas mask Air-line SCBA Particulate PAPR Chemical

Cartridge

BM BM-14 BM-19 BM-13 BM-21 N/A BM-23
30 CFR 11 TC-14G TC-19C TC-13F TC-21C TC-21C TC-23C
42 CFR 84 (enacted) TC-14G TC-19C TC-13F TC-84A TC-21C TC-23C

TC-21C respirator approval numbers for negative-pressure particulate respirators have three digits, in the form: TC-21C-###, while TC-84A respirator approval numbers have four digits, in the form: TC-84A-####.[32] 42 CFR 84 did not change regulation regarding powered-air purifying particulate respirators, so have continued under TC-21C approval, with four digits, in the form TC-21C-####.[31]

NIOSH rating limitations[edit]

NIOSH air filtration ratings do not test the fit of a respirator. Fit testing is required by OSHA for employers.[33]

Similar standards[edit]

Classic collection efficiency curve with filter collection mechanisms

A few other jurisdictions use standards similar to the NIOSH scheme to classify mechanical filter respirators. They include:

  • China (GB 2626-2019): Similar testing requirements and grades. Has "KN" and "KP" resistance levels, 90/95/99. Has additional EU-like rules on leakage.
  • Mexico (NOM-116-2009): Same grades.
  • South Korea (KMOEL - 2017-64): EU grades, KF 80/94/99 for second/first/special

See also[edit]

References[edit]

  1. ^ a b c d e f g "42 CFR Part 84 - Approval of Respiratory Protective Devices". ecfr.gov. United States Government Publishing Office. 6 February 2020. Archived from the original on 23 February 2020. Retrieved 9 February 2020.
  2. ^ "To Beard or not to Beard? That's a good Question!". NIOSH Science Blog. CDC. 2 November 2017. Archived from the original on 18 March 2020. Retrieved 27 February 2020.
  3. ^ "Counterfeit Respirators / Misrepresentation of NIOSH Approval". 23 May 2024.
  4. ^ Howard W., Spencer. "The Historic and Cultural Importance of the HAWKS NEST TUNNEL DISASTER" (PDF). American Society of Safety Professionals.
  5. ^ a b Spelce, David; Rehak, Timothy R; Meltzer, Richard W; Johnson, James S (2019). "History of U.S. Respirator Approval (Continued) Particulate Respirators". J Int Soc Respir Prot. 36 (2): 37–55. PMC 7307331. PMID 32572305.
  6. ^ "Federal Coal Mine and Safety Act of 1969". US Department of Labor, US Mine Safety and Health Administration.
  7. ^ US EPA, OP (22 February 2013). "Summary of the Occupational Safety and Health Act". www.epa.gov. Retrieved 28 August 2021.
  8. ^ NIOSH Recommended Guidelines for Personal Respiratory Protection of Workers in Health-care Facilities Potentially Exposed to Tuberculosis. 1992.
  9. ^ a b c Spelce, David; Rehak, Timothy R; Meltzer, Richard W; Johnson, James S (2019). "History of U.S. Respirator Approval (Continued) Particulate Respirators". J Int Soc Respir Prot. 36 (2): 37–55. PMC 7307331. PMID 32572305.
  10. ^ "DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention Guidelines for Preventing the Transmission of Mycobacterium Tuberculosis in Health-Care Facilities, 1994" (PDF). US Federal Register. Archived (PDF) from the original on 8 June 2024. Retrieved 8 May 2024.
  11. ^ a b c "DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service 42 CFR Part 84" (PDF). US Federal Register. pp. 26850-26893. Archived (PDF) from the original on 8 May 2024. Retrieved 8 May 2024.
  12. ^ "DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service 42 CFR Part 84 RIN 0905–AB58 Respiratory Protective Devices" (PDF). US Federal Register. 8 June 1995. Retrieved 27 April 2024.
  13. ^ Herring Jr., Ronald N. (1997). "42 CFR Part 84: It's time to change respirators... but how?". Engineer's Digest. pp. 14–23.
  14. ^ "DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service 42 CFR Part 84" (PDF). US Federal Register. pp. 26850-26893. Retrieved 8 May 2024.
  15. ^ "Respirator Trusted-Source Information Section 1: NIOSH-Approved Respirators". The National Personal Protective Technology Laboratory (NPPTL). Centers for Disease Control and Prevention. 29 January 2018. Archived from the original on 16 June 2019. Retrieved 9 February 2020.
  16. ^ a b "NIOSH Guide to the Selection and Use of Particulate Respirators". The National Institute for Occupational Safety and Health (NIOSH). Centers for Disease Control and Prevention. 6 June 2014 [January 1996]. Archived from the original on 11 August 2019. Retrieved 9 February 2020.
  17. ^ "OSHA Technical Manual Section 8VII: Chapter 2 Respiratory Protection Appendix 2-4". OSHA (TED 01-00-015 ed.). Archived from the original on 28 September 2019. Retrieved 9 February 2020.
  18. ^ a b c d e "TB Respiratory Protection Program In Health Care Facilities Administrator's Guide" (PDF). U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health. September 1999. doi:10.26616/NIOSHPUB99143. Archived (PDF) from the original on 10 October 2022. Retrieved 14 June 2024.
  19. ^ "NIOSH Pocket Guide - Asbestos". CDC. Archived from the original on 20 June 2024. Retrieved 20 June 2024.
  20. ^ "DHHS Pub 96-101 NIOSH Guide to the Selection & Use of Particulate Respirators Certified Under 42 CFR 84". NIOSH.
  21. ^ Herring Jr., Ronald N. (1997). "42 CFR Part 84: It's time to change respirators... but how?". Engineer's Digest. pp. 14–23.
  22. ^ "Considerations for Optimizing the Supply of Powered Air-Purifying Respirators (PAPRs)". U.S. Centers for Disease Control and Prevention. 19 April 2020. Archived from the original on 6 January 2023. Retrieved 25 May 2020.
  23. ^ Vanessa, Roberts (Fall 2014). "To PAPR or Not to PAPR?". Canadian Journal of Respiratory Therapy. 50 (3): 87–90. PMC 4456839. PMID 26078617.
  24. ^ "Understanding Respiratory Protection Against SARS". U.S. National Institute for Occupational Safety and Health. 9 April 2020. Archived from the original on 6 December 2020. Retrieved 26 May 2020.
  25. ^ "NIOSH Guide to the Selection and Use of Particulate Respirators Appendix E: Commonly Asked Questions and Answers About Part 84 Respirators". The National Institute for Occupational Safety and Health (NIOSH). Centers for Disease Control and Prevention. 6 June 2014. Archived from the original on 20 June 2019. Retrieved 9 February 2020.
  26. ^ "CDC - NIOSH Publications and Products - Appendices for 96-101". www.cdc.gov. 16 October 2018. Archived from the original on 20 June 2019. Retrieved 22 June 2020.
  27. ^ Lee, Byung Uk; Yermakov, Mikhail; Grinshpun, Sergey A. (2005). "Filtering Efficiency of N95- and R95-Type Facepiece Respirators, Dust-Mist Facepiece Respirators, and Surgical Masks Operating in Unipolarly Ionized Indoor Air Environments" (PDF). Aerosol and Air Quality Research. 5 (1): 25–38. doi:10.4209/aaqr.2005.06.0003. Archived (PDF) from the original on 20 January 2022. Retrieved 4 July 2024.
  28. ^ a b c d e f "LIST OF NIOSH STANDARD PROTECTIONS, CAUTIONS AND LIMITATIONS FOR APPROVAL LABELS" (PDF). CDC NIOSH.
  29. ^ a b c d e f g American National Standard for Color-Coding of Air Purifying Respirator Canisters, Cartridges, and Filters (PDF), American Industrial Hygiene Association, ANSI, 3 May 2001, archived (PDF) from the original on 2 May 2022, retrieved 3 July 2024
  30. ^ a b c "ndustrial Hygiene Field Operations Manual Technical Manual NMCPHC-TM6290.91-2 10 MAY 2021" (PDF). Archived (PDF) from the original on 17 February 2024. Retrieved 8 June 2024.
  31. ^ a b "NIOSH Guide to the Selection and Use of Particulate Respirators". CDC NIOSH. January 1996. Archived from the original on 29 February 2020. Retrieved 10 February 2020.
  32. ^ "Counterfeit Respirators / Misrepresentation of NIOSH Approval". CDC NIOSH NPPTL. 23 May 2024. Archived from the original on 13 July 2024. Retrieved 8 June 2024.
  33. ^ "Fit Test FAQs". 28 December 2021. Archived from the original on 15 June 2024. Retrieved 15 June 2024.

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