N95 respirator#History

The N95 standard does not require that the respirator be resistant to oil; two other standards, R95 and P95, add that requirement.{{ran|N2}} The N95 type is the most common filtering facepiece respirator.{{Cite web |date=2020-03-19 |title=NIOSH-Approved N95 Particulate Filtering Facepiece Respirators - A Suppliers List |url=https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/n95list1-a.html |access-date=2020-03-27 |publisher=U.S. National Institute for Occupational Safety and Health |language=en-us |df=mdy-all}} Current filters are an example of a mechanical filter respirator, which provides protection against particulates but not against gases or vapors.{{Cite web |date=2020-03-12 |title=Respirator Trusted-Source: Selection FAQs |url=https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource3selection.html |access-date=2020-03-28 |website=U.S. National Institute for Occupational Safety and Health |language=en-us |df=mdy-all}} An authentic N95 respirator is marked with the text "NIOSH" or the NIOSH logo, the filter class ("N95"), and, for most filtering facepiece respirators (respirators with non-replaceable filters), a "TC" approval number of the form 84A-####, the approval number. All N95 respirators, regardless of type, must be listed on the NIOSH Certified Equipment List (CEL){{Cite web |date=June 4, 2020 |title=Certified Equipment List | NPPTL | NIOSH | CDC |url=https://www.cdc.gov/niosh/npptl/topics/respirators/cel/default.html |website=www.cdc.gov}} or the NIOSH Trusted-Source page,{{Cite web |date=August 3, 2020 |title=Respirator Trusted-Source Information | NPPTL | NIOSH | CDC |url=https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource.html |website=www.cdc.gov}} and it must have headbands instead of ear loops.{{cite web |title=Counterfeit Respirators / Misrepresentation of NIOSH-Approval |url=https://www.cdc.gov/niosh/npptl/usernotices/counterfeitResp.html |access-date=27 October 2020 |publisher=NIOSH, Centers of Disease Control and Prevention |df=mdy-all}}

N95 respirators are considered similar to other respirators regulated under non-U.S. jurisdictions, but slightly different criteria are used to certify their performance, such as the filter efficiency, test agent and flow rate, and permissible pressure drop. For example, FFP2 respirators of the European Union are required to meet at least 94% filtration, and KN95 respirators of China are expected to meet at least 95% filtration.{{Cite web |date=2020-01-01 |title=Comparison of FFP2, KN95, and N95 and Other Filtering Facepiece Respirator Classes |url=https://multimedia.3m.com/mws/media/1791500O/comparison-ffp2-kn95-n95-filtering-facepiece-respirator-classes-tb.pdf |access-date=2020-03-28 |website=3M Technical Data Bulletin |df=mdy-all}} However, NIOSH found that some products labeled "KN95" failed to meet these standards, some of them filtering out as little as one percent.{{cite news |title=Health Canada issues recall of some KN95 masks made in China |url=https://www.cbc.ca/news/canada/saskatchewan/health-canada-issues-recall-of-some-kn95-masks-made-in-china-1.5568734 |access-date=25 October 2020 |publisher=Canadian Broadcasting Corporation |df=mdy-all}} Both the U.S. Food and Drug Administration and Health Canada require such KN95 products failing to meet the filtration standards to be re-labeled as "face masks" instead of "respirators",{{cite web |title=Certain Filtering Facepiece Respirators from China May Not Provide Adequate Respiratory Protection - Letter to Health Care Providers |url=https://www.fda.gov/medical-devices/letters-health-care-providers/certain-filtering-facepiece-respirators-china-may-not-provide-adequate-respiratory-protection-letter |archive-url=https://web.archive.org/web/20200508013924/https://www.fda.gov/medical-devices/letters-health-care-providers/certain-filtering-facepiece-respirators-china-may-not-provide-adequate-respiratory-protection-letter |url-status=dead |archive-date=May 8, 2020 |access-date=25 October 2020 |publisher=U.S. Food and Drug Administration |df=mdy-all}}{{cite web |title=Important safety information for certain respirator masks |url=https://healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2020/73063a-eng.php |access-date=25 October 2020 |publisher=Health Canada |df=mdy-all}} when being sold in the U.S. and Canada.

Canadian labor law normally requires NIOSH-approved respirators, like the N95.{{ran|S3}} However, in 2021, to reduce respirator shortages in Canada, the CSA Group released standard CSA Z94.4.1, allowing for the manufacture of CA-N95 respirators,{{cite web|url=https://www.canada.ca/en/health-canada/services/drugs-medical-devices/masks-respirators/information-users.html|title=Medical masks and respirators: Information for users|date=June 12, 2024 |access-date=2025-02-04|publisher=Health Canada}}{{cite web|url=https://www.ohcow.on.ca/wp-content/uploads/2024/03/Revising-CanadianRespiratorStandard.pdf|title=Revising the CSA Respirator Standard|date=March 2024|first=Simon|last=Smith}} which are not approved or cleared for use in the United States.

{{Wikisource|Counterfeit & Altered Respirators: The Importance of Checking for NIOSH Certification|Counterfeit & Altered Respirators: The Importance of Checking for NIOSH Certification (2012)}}

{{gallery

|title=Examples of N95 respirators

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|footer={{center|Thoroughly check the NIOSH Certified Equipment List, and compare the look and feel to known good respirators{{break}}to verify that a suspect respirator is a NIOSH-approved N95.{{cite web|url=https://www.cdc.gov/niosh/npptl/usernotices/counterfeitResp.html|title=Counterfeit Respirators / Misrepresentation of NIOSH Approval|date=May 23, 2024 }}}}

|2200-Cropped.jpg

|alt1=A Moldex N95 respirator

|A Moldex 2200N95 disposable filtering facepiece respirator, with TC approval number on the strap, TC-84A-0327

|3M 1860 N952020.jpg

|alt2=A 3M 1860 filtering facepiece respirator with fluid resistance

|Surgical N95 respirators for use in health care are both approved by NIOSH (as a respirator) and cleared by FDA (as a fluid resistant surgical mask), TC-84A-0006

|Elastomeric respirator exploded view (Respirator types snapshot at 1024).png

|alt3=Moldex Elastomeric Respirator with N95 filter circled

|An elastomeric respirator with N95 filters installed. Note the lack of a TC number; according to OSHA, TC numbers may be located in the respirator manual or on respirator packaging.{{cite web|url=https://www.osha.gov/video/respiratory-protection/niosh/transcript|title=Transcript for the OSHA Training Video Entitled Counterfeit & Altered Respirators: The Importance of Checking for NIOSH Certification|date=January 2012|publisher=US Department of Labor, OSHA|access-date=3 June 2024|archive-date=3 June 2024|archive-url=https://web.archive.org/web/20240603060828/https://www.osha.gov/video/respiratory-protection/niosh/transcript|url-status=live}}

}}

{{For|a broader, non-regulatory historical overview|Respirator#History}}

=== Early US respirator standards ===

File:Hawks Nest Tunnel disaster - 2.jpg memorial grave site]]

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.{{cite web|url=https://www.assp.org/docs/default-source/psj-articles/vpspencer_0223.pdf?sfvrsn=afa39647_0|title=The Historic and Cultural Importance of the HAWKS NEST TUNNEL DISASTER|first=Spencer|last=Howard W.|publisher=American Society of Safety Professionals}} 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, under 30 CFR 14 Schedule 21.{{cite journal|first1=David|last1=Spelce|first2=Timothy R|last2=Rehak|first3=Richard W|last3=Meltzer|first4=James S|last4=Johnson|date=2019|title=History of U.S. Respirator Approval (Continued) Particulate Respirators|journal=J Int Soc Respir Prot|volume=36 |issue=2 |pages=37–55 |pmid=32572305 |pmc=7307331 }}

The Federal Coal Mine Health and Safety Act establishing MESA (later MSHA),{{cite web|url=https://www.msha.gov/federal-coal-mine-and-safety-act-1969|title=Federal Coal Mine and Safety Act of 1969|publisher=US Department of Labor, US Mine Safety and Health Administration}} the Occupational Safety and Health Act of 1970, establishing NIOSH,{{Cite web|last=US EPA|first=OP|date=2013-02-22|title=Summary of the Occupational Safety and Health Act|url=https://www.epa.gov/laws-regulations/summary-occupational-safety-and-health-act|access-date=2021-08-28|website=www.epa.gov|language=en}} as well as other regulations established around the time, reshuffled regulatory authority for respirators, and moved regulations from Part 14 to Part 11 by 1972,{{ran|N2}} but nonetheless continued the use of USBM-era regulations.

{{About-distinguish-text|the Part 84 respirator regulation enacted in 1995|the older, 1973 Part 84 regulation for colorimetric detector tubes,{{citation |url=https://www.govinfo.gov/content/pkg/FR-1973-05-08/pdf/FR-1973-05-08.pdf|title=Federal Register |volume=58 |issue=88 |date=1973-05-08 |page=11458}} which will not be discussed here}}

Historically, respirators in the US had generally been approved by MESA/MSHA/NIOSH under federal regulation 30 CFR 11.{{ran|S1}} Plans for overhauling Part 11 regulations had been discussed since the late 1980s,{{ran|C1}} with the first proposed rule being published in the Federal Register on August 27, 1987. From the start, respirator regulations were planned to be moved from Title 30 to Title 42, Part 84 in the Code of Federal Regulations, along with the elimination of joint-approval between NIOSH and MSHA. Respirator assigned protection factors were also to be updated, along with chemical cartridge requirements.{{cite journal | url=https://doi.org/10.1080/08828032.1988.10388554 | doi=10.1080/08828032.1988.10388554 | title=Personal Protective Equipment | date=1988 | last1=Moran | first1=John B. | journal=Applied Industrial Hygiene | volume=3 | issue=5 | url-access=subscription }}{{citation|url=https://www.govinfo.gov/content/pkg/FR-1987-08-27/pdf/FR-1987-08-27.pdf|title= Revision of Tests and Requirements for Certification of Permissability of Respiratory Protective Devices Used in Mines and Mining |work=Federal Register |volume=52 |issue=166 |date=1987-08-27 |page=32402}}

{{US respirator topics}}

In 1992, the multidrug-resistant tuberculosis task force within the CDC was tasked with reducing the incidences of hospital acquired TB infections. TB infections had traditionally occurred mainly in underserved groups and areas, as well as the very young and elderly, but regardless, usually had around a 10% chance of turning into an active TB infection in a given person's lifetime. However, HIV/AIDS, (where the outbreak in the US was in full force at the time) was noted to be one of the strongest factors for TB activation, since most TB outbreaks and mortalities reported at the time involved healthcare workers and patients infected with HIV. Respiratory protection and the performance of respirators were emphasized in the 1994 guidelines to controlling TB, which, at the time, were limited to respirators equipped with HEPA filters.{{efn|name=hepa|This refers to the MSHA's definition of 'HEPA' under 30 CFR Part 11 for respirators, which is 99.97% filtration of 0.3 micron DOP, not the EN 1822 or ISO 29463 definition of HEPA.}}{{ran|C3}}

To quickly address the HEPA-only{{efn|name=hepa}} respirator requirement for TB controls, stemming from the lack of biological protection in the existing 30 CFR 11 standards (which were mainly designed for miners), NIOSH aimed to have the proposed 42 CFR rule changes finished by the end of 1994. The proposal at the time would drop the HEPA classification for non-powered respirators, and add three respirator types, at the time called Type A, B and C, with filtration efficiencies of greater than or equal to 99.97%, 99%, and 95% respectively,{{ran|C1}} with Type C corresponding to the current N95 standard.

According to NIOSH, all the new respirator types proposed in 42 CFR 84, including Type C (later N95), would meet the CDC's requirement for protection against TB, and would provide avenues for cheaper NIOSH-approved respirators without the need for HEPA{{efn|name=hepa}} or NIOSH class-100 filters.{{ran|C1}}

After the passage of 42 CFR 84, a 1999 NIOSH guide for health care administrators noted that respirators selected for TB prevention under 42 CFR would likely be N95 respirators.{{cite web |title=TB Respiratory Protection Program In Health Care Facilities Administrator's Guide |publisher=U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health|date=September 1999|doi=10.26616/NIOSHPUB99143 |url=https://www.cdc.gov/niosh/docs/99-143/pdfs/99-143.pdf?id=10.26616/NIOSHPUB99143}}

==== Approval of Part 84 and replacement of 30 CFR 11 ====

On July 10, 1995, in response to respirators exhibiting "low initial efficiency levels", new 42 CFR 84 standards, including the N95 standard, were enforced under a three-year transition period,{{ran|C4}} ending on July 10, 1998.{{ran|N2}} The standard for N95 respirators includes, but is not limited to, a filtration of at least 95% under a 0.3 micrometer{{ran|C4}} 200 milligram test load of sodium chloride. Standards and specifications are also subject to change.Note: the following source cites July 1, 1998 as the end date for the transition period, contradicting official NIOSH publications. {{cite magazine|last=Herring Jr.|first=Ronald N.|date=1997|title=42 CFR Part 84: It's time to change respirators... but how?|magazine=Engineer's Digest|pages=14–23}}{{ran|N2}}

Once 42 CFR 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).{{ran|C1}}{{cite press release| title=Changes in Occupational Safety Regs Will Permit Better Respirators to Protect Against Dust and Disease| date=June 2, 1995 |publisher=NIOSH |url=http://www.cdc.gov/niosh/press1.html |archive-url=https://web.archive.org/web/19961231021732/http://www.cdc.gov/niosh/press1.html |archive-date=1996-12-31 }}

{{Wikisource|1=TB Respiratory Protection - Administrators Review|2=TB Respiratory Protection - Administrator's Review}}

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|Niosh tb guidelines.pdf

|alt1=NIOSH Recommended Guidelines for Personal Respiratory Protection scan

|Respirator guidelines for TB were created by NIOSH as a result of the HIV/AIDS-induced outbreak in US hospitals{{break}}(Read on Wikisource)

|File:CFR-2003-title42-vol1.pdf

|alt2=An image of a the cover of the United States CFR. For Part 84, go to page 501.

|N95 standard development is documented in the Federal Register, and the Code of Federal Regulations

|Respirators - Your TB Defense.webm

|alt3=2000 NIOSH TV video

|NIOSH video on TB respirator usage, from the year 2000

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=== Voluntary respirator use ===

{{Wikisource-multi|29 CFR 1910.134 Appendix D|Non-occupational Uses of Respiratory Protection – What Public Health Organizations and Users Need to Know|t2=Non-occupational Uses of Respiratory Protection – What Public Health Organizations and Users Need to Know (2018)}}

When in an environment where no designated hazards are present, OSHA mandated respirator requirements are limited to Appendix D of 1910.134. Voluntary respirator users under Appendix D are only obligated to follow manufacturer instructions for maintenance, use, and warnings, and to keep track of the respirator. OSHA encourages the use of respirators, even if only voluntarily.{{ran|C5}}

OSHA advises voluntary respirator users receive a copy of 1910.134 Appendix D, as well as verify that the respirator used, be it powered-air purifying, self-contained, or facepiece-filtering, is not a potential health hazard.{{cite web|url=http://osha.gov/video/respiratory-protection/voluntary-use/transcript|title=Transcript for the OSHA Training Video Entitled Voluntary Use of Respirators|date=2012}}

File:EPA wildfire smoke respirator guide.png

The EPA recommends wearing a N95 or P100 respirator during a wildfire for protection against smoke.{{efn|name=warning|N95/P100 respirator cautions and limitations:{{ran|N2}}{{break}}A—Not for use in atmospheres containing less than 19.5% oxygen.{{break}}B—Not for use in atmospheres immediately dangerous to life or health.{{break}}N95 respirators are not SCBA respirators, which are sometimes designed for IDLH situations. Voluntary respirator users are advised by OSHA to read Appendix D of 1910.134 before using their respirator.}} Masks to avoid are those with a single strap (also known as a dust mask) or a mask with earloops.{{cite web |url=https://www.epa.gov/sites/default/files/2018-11/documents/reduce-your-smoke-exposure.pdf |publisher=US EPA |date=November 2018 |title=Reduce your Smoke Exposure}}

In addition to recommending NIOSH-approved respirators, the EPA also recommends building air purifiers to improve indoor air quality when commercial air purifiers are unavailable or unaffordable.{{cite web |url=https://www.epa.gov/emergencies-iaq/wildfires-and-indoor-air-quality-iaq |title=Wildfires and Indoor Air Quality (IAQ) |date=December 11, 2018 |access-date=2024-01-08 |publisher=US EPA}}

{{As of|2024|10|post=,}} NIOSH is in the process of developing a hazard review on smoke exposure among outdoor workers.{{cite web |url=https://www.cdc.gov/niosh/outdoor-workers/about/wildfire-smoke.html |title=Wildland Fire Smoke |date=2024-10-31 |publisher=CDC NIOSH}}{{cite web |url=https://www.safetyandhealthmagazine.com/articles/25986-exposure-to-wildfire-smoke-niosh-wants-feedback-on-draft-hazard-review |title=Exposure to wildfire smoke: NIOSH wants feedback on draft hazard review |date=2024-09-24 |publisher=Safety and Health Magazine}} The current draft, {{as of|2024|08|23|df=US|lc=y|post=,}} advises the use of N95 respirators, as well as engineering and administrative controls.{{cite web |url=https://www.cdc.gov/niosh/docket/review/docket352a/pdf/FINAL-20-Green-V4-CLEAN-3RD-Edits-Applied-FINAL-508R.pdf |title=EXTERNAL REVIEW DRAFT NIOSH Hazard Review Wildland Fire Smoke Exposure Among Farmworkers and Other Outdoor Workers |date=2024-08-23}}

File:Three Key Factors Required for a Respirator to be Effective.pdf

File:Facial hairstyles and filtering facepiece respirators.pdf

Fit testing is a critical component to a respiratory protection program whenever workers use tight-fitting respirators in a hazardous environment. OSHA (US) requires an initial respirator fit test to identify the right model, style, and size respirator for each worker; as well, as annual fit tests. Additionally, tight-fitting respirators, including the N95, require a user seal check each time one is put on. Facial hair at the sealing area of the respirator will cause it to leak.

When use of a respirator is mandated by an employer, OSHA regulations require a medical evaluation.{{Cite web|url=https://www.osha.gov/video/respiratory-protection/med-evaluations/transcript#:~:text=Before%20you%20use%20a%20respirator,to%20perform%20the%20medical%20evaluation.|title=Medical Evaluations for Workers Who Use Respirators|website=U.S. Occupational Safety and Health Administration|access-date=2024-01-30|df=mdy-all}} In the United States medical evaluation is required once, prior to initial fit testing and use, although it may need to be repeated if any adverse signs or symptoms are observed.{{cite web|url=https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource3healthcare.html|title=Ancillary Respirator Information|date=2018-01-26|website=U.S. National Institute for Occupational Safety and Health|access-date=12 February 2020|df=mdy-all}} Correct use of the respirator decreases the chances of airborne contamination by viruses.{{Cite journal |last1=Hui|first1=David S.|last2=Chow|first2=Benny K.|last3=Chu|first3=Leo|last4=Ng|first4=Susanna S.|last5=Lee|first5=Nelson|last6=Gin|first6=Tony|last7=Chan|first7=Matthew T. V.|date=2012-12-05|title=Exhaled Air Dispersion during Coughing with and without Wearing a Surgical or N95 Mask|journal=PLOS ONE|language=en|volume=7|issue=12|pages=e50845|doi=10.1371/journal.pone.0050845|issn=1932-6203|pmc=3516468|pmid=23239991|bibcode=2012PLoSO...750845H|df=mdy-all|doi-access=free}}

For persons who are medically disqualified from negative-pressure respirators, or who cannot pass a fit test due to facial hair or other reasons, a powered air-purifying respirator is a possible alternative.{{Cite web|url=https://blogs.cdc.gov/niosh-science-blog/2017/07/06/elastomerics/|title=Understanding respiratory protection options in healthcare: the overlooked elastomeric|last=Bach|first=Michael|date=2017-07-06|website=NIOSH Science Blog|language=en-us|access-date=2020-04-21|df=mdy-all}}{{Cite web|url=https://www.ehstoday.com/ppe/respirators/article/21906717/constructing-a-powered-air-purifying-respirator-system|title=Constructing a Powered Air Purifying Respirator System|last=Garvey|first=Donald J.|date=2010-04-01|website=EHS Today|access-date=2020-04-21|df=mdy-all}}

The rules on wearing respirators are similar in Canada. {{as of|2024|12|post=,}} SOR 86-304 dictates that, when employees are expected to do work in a hazardous environment, they must wear respirators approved by NIOSH, and must follow the procedures in CSA Z94.4 when fitting respirators.{{ran|S3}}

N95 respirators are also designed for industrial use in sectors such as mining and construction.{{cite web |url=https://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-surgical-masks-face-masks-and-barrier-face-coverings#:~:text=provide%20full%20protection.-,N95%20Respirators%20in%20Industrial%20and%20Health%20Care%20Settings,to%20dust%20and%20small%20particles.|archive-url=https://web.archive.org/web/20210916072303/https://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-surgical-masks-face-masks-and-barrier-face-coverings#:~:text=provide%20full%20protection.-,N95%20Respirators%20in%20Industrial%20and%20Health%20Care%20Settings,to%20dust%20and%20small%20particles.|url-status=dead|archive-date=September 16, 2021|title=N95 Respirators, Surgical Masks, Face Masks, and Barrier Face Coverings

|publisher=US Food and Drug Administration|date=10 March 2023|access-date=27 April 2024}} They have also been shown to be effective as protection against engineered nanoparticles.{{Cite journal|url=https://www.cdc.gov/niosh/docs/2016-102/|title=Building a Safety Program to Protect the Nanotechnology Workforce: A Guide for Small to Medium-Sized Enterprises|date=March 2016|website=U.S. National Institute for Occupational Safety and Health|doi=10.26616/NIOSHPUB2016102|language=en-us|access-date=2017-03-05|df=mdy-all|doi-access=free|hdl=10919/76615|hdl-access=free |last1=Hull |first1=Matthew S. }}{{Rp|12–14}}{{Cite web|url=https://blogs.cdc.gov/niosh-science-blog/2011/12/07/resp-nano/|title=Respiratory Protection for Workers Handling Engineered Nanoparticles|date=2011-12-07|website=NIOSH Science Blog|publisher=U.S. National Institute for Occupational Safety and Health|language=en-us|access-date=2017-03-15|df=mdy-all}}{{Cite web|url=https://www.gpo.gov/fdsys/pkg/FR-2011-05-06/html/2011-11127.htm|title=Multi-Walled Carbon Nanotubes; Significant New Use Rule (40 CFR 721.10155)|date=2011-05-06|website=Federal Register, Volume 76 Issue 88|publisher=U.S. Environmental Protection Agency via U.S. Government Publishing Office|access-date=2017-03-15|df=mdy-all}}

According to the NIOSH Respirator Selection Logic, respirators with filters in the N, R, and P series are recommended for concentrations of hazardous particulates that are greater than the relevant occupational exposure limit but less than the immediately dangerous to life or health level and the manufacturer's maximum use concentration, subject to the respirator having a sufficient assigned protection factor.{{Cite web|title=Dust Masks, What's in a Rating {{!}} N95, P95, N100 etc.|url=https://www.envirosafetyproducts.com/resources/dust-masks-whats-the-difference.html|access-date=2021-04-12|website=www.envirosafetyproducts.com}}

N series respirators, including the N95 respirator, are only effective in the absence of oil particles, such as lubricants, cutting fluids, or glycerine. For substances hazardous to the eyes, a respirator equipped with a full facepiece, helmet, or hood is recommended. They are not effective during firefighting, in oxygen-deficient atmosphere, or in an unknown atmosphere; in these situations a self-contained breathing apparatus is recommended instead. They are not effective against hazardous gases or vapors, for which a cartridge respirator is recommended.{{Cite journal|url=https://www.cdc.gov/niosh/docs/2005-100/default.html|title=NIOSH respirator selection logic|last=Bollinger|first=Nancy|date=2004-10-01|website=U.S. National Institute for Occupational Safety and Health|pages=5–9|language=en-us|doi=10.26616/NIOSHPUB2005100|doi-access=free|df=mdy-all}}

In industrial settings where infectious disease exposure is not a concern, users can wear and reuse a filtering facepiece respirator until it is damaged, soiled, or causing noticeably increased breathing resistance, unless there is a manufacturer-specified duration of use. However, in laboratories at biosafety level 2 and higher, respirators are recommended to be discarded as hazardous waste after a single use.{{Cite web|url=https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource3respreuse.html|title=Respirator Reuse FAQs|date=2018-01-30|website=U.S. National Institute for Occupational Safety and Health|language=en-us|access-date=2020-04-20|df=mdy-all}}

Some industrial N95 series respirators have an exhaust valve to improve comfort, making exhalation easier, reducing leakage on exhalation and steaming-up of glasses. Research has indicated that wearing a valved N95 respirator does provide some source control to prevent the spread of diseases like COVID-19 when worn by asymptomatic infected users, at a level similar to that of a surgical or cloth facemask, although it is not equivalent to the performance of unvalved respirators.{{Cite journal |date=2020-12-01 |title=Filtering Facepiece Respirators with an Exhalation Valve: Measurements of Filtration Efficiency to Evaluate Their Potential for Source Control |journal= NIOSH |url=https://www.cdc.gov/niosh/docs/2021-107/ |language=en |doi=10.26616/nioshpub2021107 |doi-access=free |last1=Portnoff |first1=L |last2=Schall |first2=J |last3=Brannen |first3=J |last4=Suhon |first4=N |last5=Strickland |first5=K |last6=Meyers |first6=J |publisher=U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health |number=Publication No. 2021-107}} The same study found that "[m]odifications [such as the use of an electrocardiogram pad or surgical tape secured over the valve from the inside of the FFR] [...] can further reduce particle emissions".

File:USNS Mercy Sailor Treats Patient (49785699691).jpg

Respirators used in healthcare are traditionally a specific variant called a surgical respirator, which is both approved by NIOSH as a respirator and cleared by the Food and Drug Administration as a medical device similar to a surgical mask.{{Cite web|url=https://ohsonline.com/articles/2014/05/01/comparison-respiratory.aspx|title=A Comparison of Surgical Masks, Surgical N95 Respirators, and Industrial N95 Respirators|date=2014-05-01|website=Occupational Health & Safety|language=en|access-date=2020-04-07|df=mdy-all}} These may also be labeled "Surgical N95", "medical respirators", or "healthcare respirators".{{cite web|title=Respirator Trusted-Source Information: Ancillary Respirator Information|url=https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource3healthcare.html|date=2018-01-26|website=U.S. National Institute for Occupational Safety and Health|access-date=12 February 2020|df=mdy-all}} The difference lies in the extra fluid-resistant layer outside, typically colored blue.{{cite web |url=https://multimedia.3m.com/mws/media/1839703O/surgical-n95-vs-standard-n95-which-to-consider.pdf |title=Surgical N95 vs. Standard N95 – Which to Consider? |publisher=3M Company |date=March 2020 |access-date=2022-06-12}} In addition to 42 CFR 84, surgical N95s are regulated under FDA regulation 21 CFR 878.4040.

In the United States, the Occupational Safety and Health Administration (OSHA) requires healthcare workers who are expected to perform patient activities with those suspected or confirmed to be infected with COVID-19 to wear respiratory protection, such as an N95 respirator. The CDC recommends the use of respirators with at least N95 certification to protect the wearer from inhalation of infectious particles including Mycobacterium tuberculosis, avian influenza, severe acute respiratory syndrome (SARS), pandemic influenza, and Ebola.{{Cite book|url=https://www.cdc.gov/infectioncontrol/pdf/guidelines/isolation-guidelines-H.pdf|title=2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings|date=July 2019|publisher=U.S. Centers for Disease Control and Prevention|pages=55–56|access-date=February 9, 2020|df=mdy-all}}

Unlike a respirator, a surgical mask is designed to provide barrier protection against droplets and does not have an air-tight seal and thus does not protect its wearer against airborne particles such as virus material to the same extent.{{Cite web|url=https://blogs.cdc.gov/niosh-science-blog/2020/03/16/n95-preparedness/|title=Proper N95 Respirator Use for Respiratory Protection Preparedness|last1=D'Alessandro|first1=Maryann M.|last2=Cichowicz|first2=Jaclyn Krah|date=2020-03-16|website=NIOSH Science Blog|language=en-us|access-date=2020-03-27|df=mdy-all}} {{PD-inline}}

{{Further |COVID-19 pandemic#Face masks and respiratory hygiene}}

During crisis situations where there is a shortage of N95 respirators, such as the COVID-19 pandemic, the U.S. Centers for Disease Control and Prevention (CDC) has recommended strategies for optimizing their use in healthcare settings.{{Cite web|url=https://www.cdc.gov/coronavirus/2019-ncov/hcp/respirators-strategy/crisis-alternate-strategies.html|title=Strategies for Optimizing the Supply of N95 Respirators: Crisis/Alternate Strategies|date=2020-03-17|website=U.S. Centers for Disease Control and Prevention|language=en-us|access-date=2020-03-28|df=mdy-all}} {{PD-inline}} N95 respirators can be used beyond their manufacturer-designated shelf life, although components such as the straps and nose bridge material may degrade, making it particularly important that the wearer perform the expected seal check.{{Cite web|url=https://www.cdc.gov/coronavirus/2019-ncov/release-stockpiled-N95.html|title=Release of Stockpiled N95 Filtering Facepiece Respirators Beyond the Manufacturer-Designated Shelf Life: Considerations for the COVID-19 Response|date=2020-02-28|website=U.S. Centers for Disease Control and Prevention|language=en-us|access-date=2020-03-28|df=mdy-all}} N95 respirators can be reused a limited number of times after being removed, as long as they have not been used during aerosol-generating procedures and are not contaminated with patients' bodily fluids, because this increases the risk of surface contamination with pathogens. The respirator manufacturer may recommend a maximum number of donnings or uses; if no manufacturer guidance is available, preliminary data suggests limiting to five uses per device.{{Cite web|url=https://www.cdc.gov/niosh/topics/hcwcontrols/recommendedguidanceextuse.html|title=Recommended Guidance for Extended Use and Limited Reuse of N95 Filtering Facepiece Respirators in Healthcare Settings|date=2020-03-27|website=U.S. National Institute for Occupational Safety and Health|language=en-us|access-date=2020-03-28|df=mdy-all}} Respirators approved under standards used in other countries and are similar to NIOSH-approved N95 respirators{{Em dash}}including FFP2 and FFP3 respirators regulated by the European Union{{Em dash}}can be used.

According to NIOSH, respirators may still be used in crisis situations if standard respirator fit testing is not available, as a respirator will still provide better protection than a surgical mask or no mask. In this case, best practices for getting a good face seal include trying different models or sizes, using a mirror or asking a colleague to check that the respirator is touching the face, and doing multiple user seal checks.

Given that the global supply of personal protective equipment (PPE) may be insufficient during a pandemic, in 2020, the World Health Organization recommended minimizing the need for PPE through telemedicine; physical barriers such as clear windows; allowing only those involved in direct care to enter a room with a COVID-19 patient; using only the PPE necessary for the specific task; continuing use of the same respirator without removing it while caring for multiple patients with the same diagnosis; monitoring and coordinating the PPE supply chain; and discouraging the use of masks for asymptomatic individuals.{{Cite web|url=https://apps.who.int/iris/bitstream/handle/10665/331215/WHO-2019-nCov-IPCPPE_use-2020.1-eng.pdf|title=Rational use of personal protective equipment for coronavirus disease 2019 (COVID-19)|date=2020-02-27|website=World Health Organization|access-date=2020-03-21|df=mdy-all}}

When it is no longer possible for all healthcare workers to wear N95 respirators when caring for a COVID-19 patient, the CDC recommends that respirators be prioritized for workers performing aerosol-generating procedures on symptomatic persons, and those within three feet of an unmasked symptomatic person. Under these conditions, masking of symptomatic patients with at least a surgical mask and maintaining distance from the patient are particularly important to reduce the risk of transmission. When no respirators are left, workers who are at higher risk for severe illness may be excluded from caring for patients, and workers who have clinically recovered from COVID-19 may be preferred to care for patients. Portable fans with HEPA filters may also be used to increase ventilation in isolation rooms when surgical masks are being used in place of respirators. If neither respirators nor surgical masks are available, as a last resort, it may be necessary for healthcare workers to use masks that have never been evaluated or approved by NIOSH or homemade masks, such as cloth face masks, although caution should be exercised when considering this option.

Disposable filtering facepiece respirators such as N95 respirators are not approved for routine decontamination and reuse as standard of care. However, their decontamination and reuse may need to be considered as a crisis capacity strategy to ensure continued availability.{{Cite web|url=https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html|title=Decontamination and Reuse of Filtering Facepiece Respirators|date=2020-04-09|website=U.S. Centers for Disease Control and Prevention|language=en-us|access-date=2020-04-20|df=mdy-all}} {{PD-inline}}{{cite journal|vauthors=Srinivasan S, Peh W |title=N95 Filtering Facepiece Respirators during the COVID-19 Pandemic: Basics, Types, and Shortage Solutions |journal=Malaysian Orthopedic Journal |year=2020 |volume=14|issue=2 |pages=16–22 |doi=10.5704/MOJ.2007.002 |pmid=32983373 |pmc=7513643 |df=mdy-all|doi-access=free }}

There have been efforts to evaluate cleaning methods for respirators in emergency shortages, although there is concern that this may reduce filter performance, or affect mask fit by deforming the mask.{{Cite journal|last1=Viscusi|first1=Dennis J.|last2=Bergman|first2=Michael S.|last3=Eimer|first3=Benjamin C.|last4=Shaffer|first4=Ronald E.|date=November 2009|title=Evaluation of Five Decontamination Methods for Filtering Facepiece Respirators|journal=Annals of Occupational Hygiene|volume=53|issue=8|pages=815–827|doi=10.1093/annhyg/mep070|issn=0003-4878|pmc=2781738|pmid=19805391}}{{Cite web|url=https://stanfordmedicine.app.box.com/v/covid19-PPE-1-2|title=Addressing COVID-19 Face Mask Shortages|date=2020-03-25|website=Stanford University School of Medicine|access-date=2020-03-27|df=mdy-all}}{{Cite web|url=https://www.livescience.com/sanitizing-medical-masks-for-reuse-coronavirus.html|title=Doctors scramble for best practices on reusing medical masks during shortage|last=March 2020|first=Rafi Letzter – Staff Writer |website=livescience.com|date=March 24, 2020|language=en|access-date=2020-03-27|df=mdy-all}} Duke University researchers have published a method for cleaning N95 respirators without damaging them using vaporized hydrogen peroxide to allow reuse for a limited number of times.{{Cite web |url=https://www.safety.duke.edu/sites/default/files/N-95_VHP-Decon-Re-Use.pdf |title=Decontamination and Reuse of N95 Respirators with Hydrogen Peroxide Vapor to Address Worldwide Personal Protective Equipment Shortages During the SARS-CoV-2 (COVID-19) Pandemic |first1=Antony |last1=Schwartz |first2=Matthew |last2=Stiegel |first3=Nicole |last3=Greeson |first4=Andrea |last4=Vogel |first5=Wayne |last5=Thomann |first6=Monte |last6=Brown |first7=Gregory D. |last7=Sempowski |first8=Thomas Scott |last8=Alderman |first9=James Patrick |last9=Condreay |first10=James |last10=Burch |first11=Cameron |last11=Wolfe |first12=Becky |last12=Smith |first13=Sarah |last13=Lewis |display-authors=3 |website=Duke University |access-date=2020-03-28 |df=mdy-all |archive-date=March 27, 2020 |archive-url=https://web.archive.org/web/20200327185110/https://www.safety.duke.edu/sites/default/files/N-95_VHP-Decon-Re-Use.pdf |url-status=dead }}{{cite news|last=Andrew|first=Scottie|url=https://www.cnn.com/2020/03/27/health/n95-respirator-rewear-coronavirus-duke-trnd/index.html|title=Duke researchers are decontaminating N95 masks so doctors can reuse them to treat coronavirus patients|date=March 27, 2020|newspaper=CNN}}{{Cite web|url=https://indyweek.com/api/content/f19f2182-6f74-11ea-9c30-1244d5f7c7c6/|title=Duke Researchers Find Way to Decontaminate and Reuse N95 Masks, Possibly Alleviating Critical Shortfall|last=Billman|first=Jeffrey C.|date=2020-03-26|website=INDY Week|language=en-us|access-date=2020-03-27|df=mdy-all|archive-date=July 19, 2020|archive-url=https://web.archive.org/web/20200719053421/https://indyweek.com/api/content/f19f2182-6f74-11ea-9c30-1244d5f7c7c6/|url-status=dead}} Battelle received an Emergency Use Authorization from the U.S. Food and Drug Administration for its technology used to sterilize N95 respirators.{{Cite web|url=https://www.usatoday.com/story/news/nation/2020/03/29/coronavirus-fda-eases-restrictions-mask-sterilization-technology/2936670001/|title=FDA lifts restrictions on Ohio-based Battelle's mask-sterilizing technology amid coronavirus shortages|last=Schladen|first=Marty|date=2020-03-29|website=USA Today|language=en-US|access-date=2020-03-30|df=mdy-all}}

OSHA does not currently have any standards for disinfecting N95 respirators. NIOSH recommends that during shortages N95 respirators may be used up to five times without cleaning them, as long as aerosol-generating procedures are not performed, and respirators are not contaminated with patients' bodily fluids. Contamination can be reduced by wearing a cleanable face shield over an N95 respirator, as well as using clean gloves when donning and seal-checking a used N95 respirator and discarding the gloves immediately after. According to CDC, ultraviolet germicidal irradiation, vaporous hydrogen peroxide and moist heat showed the most promise as potential methods to decontaminate N95 respirators and other filtering facepiece respirators.

==== Contrast with surgical mask ====

File:Understanding the difference between surgical masks and N95 respirators.pdfs and N95 respirators]]

A surgical mask is a loosely-placed, unsealed barrier, meant to stop droplets, and other liquid-borne particles from the mouth and nose that may contain pathogens.{{Cite web|url=http://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-and-surgical-masks-face-masks|title=N95 Respirators and Surgical Masks (Face Masks)|date=2020-03-11|website=U.S. Food and Drug Administration|language=en|access-date=2020-03-28|df=mdy-all}}{{dead link|date=May 2025|bot=medic}}{{cbignore|bot=medic}} {{PD-inline}}

A surgical mask may not block all particles, due to the lack of fit between the surface of the face mask and the face. The filtration efficiency of a surgical mask ranges between 10% and 90% for any given manufacturer, when measured using tests required for NIOSH certification. A study found that 80–100% of subjects failed an OSHA-accepted qualitative fit test, and a quantitative test showed between 12 and 25% leakage.{{Cite web|url=https://blogs.cdc.gov/niosh-science-blog/2009/10/14/n95/|title=N95 Respirators and Surgical Masks|last1=Brosseau|first1=Lisa|last2=Ann|first2=Roland Berry|date=2009-10-14|website=NIOSH Science Blog|language=en-us|access-date=2020-03-28|df=mdy-all}} {{PD-inline}}

A CDC study found that in public indoor settings, consistently wearing a respirator was linked to a 83% lower risk of testing positive for COVID-19, as compared to a 66% reduction when using surgical masks, and 56% for cloth.{{Cite journal|url=https://www.cdc.gov/mmwr/volumes/71/wr/mm7106e1.htm|title=Effectiveness of Face Mask or Respirator Use in Indoor Public Settings for Prevention of SARS-CoV-2 Infection — California, February–December 2021|date=2022 |doi=10.15585/mmwr.mm7106e1 |access-date=January 30, 2024 |last1=Andrejko |first1=Kristin L. |last2=Pry |first2=Jake M. |last3=Myers |first3=Jennifer F. |last4=Fukui |first4=Nozomi |last5=Deguzman |first5=Jennifer L. |last6=Openshaw |first6=John |last7=Watt |first7=James P. |last8=Lewnard |first8=Joseph A. |last9=Jain |first9=Seema |last10=Abdulrahim |first10=Yasmine |last11=Barbaduomo |first11=Camilla M. |last12=Bermejo |first12=Miriam I. |last13=Cheunkarndee |first13=Julia |last14=Cornejo |first14=Adrian F. |last15=Corredor |first15=Savannah |last16=Dabbagh |first16=Najla |last17=Dong |first17=Zheng N. |last18=Dyke |first18=Ashly |last19=Fang |first19=Anna T. |last20=Felipe |first20=Diana |last21=Frost |first21=Paulina M. |last22=Ho |first22=Timothy |last23=Javadi |first23=Mahsa H. |last24=Kaur |first24=Amandeep |last25=Lam |first25=Amanda |last26=Li |first26=Sophia S. |last27=Miller |first27=Monique |last28=Ni |first28=Jessica |last29=Park |first29=Hyemin |last30=Poindexter |first30=Diana J. |journal=MMWR. Morbidity and Mortality Weekly Report |volume=71 |issue=6 |pages=212–216 |pmid=35143470 |pmc=8830622 |display-authors=1 }}

{{See also|HIV/AIDS in the United States|Source control (respiratory disease)#US HIV/AIDS Epidemic}}

File:N95 stop.svg in 1997, this sign would be paired with the words "No Admittance Without Wearing a Type N95 or More Protective Respirator" near where tuberculosis was present{{citation|url=https://www.osha.gov/laws-regs/federalregister/1997-10-17 |title=Occupational Exposure to Tuberculosis, Proposed Rule |work=Federal Register |volume=62 |issue=201 |date=1997-10-17 |via=OSHA |id=62:54159-54309}} ]]

While NIOSH was busy finishing 42 CFR 84 respirator regulations (including the N95), other agencies and groups (such as the SEIU{{cite journal | url=https://doi.org/10.1086/646909 | doi=10.1086/646909 | title=OSHA Announces Plans for a TB Standard | date=1994 | last1=Pugliese | first1=Gina | journal=Infection Control & Hospital Epidemiology | volume=15 | issue=4 | page=277 | url-access=subscription }}) were advocating for new standards for the prevention of TB. In 1992, the Labor Coalition to Fight TB in the Workplace started lobbying OSHA to create advisories and formal rules to protect workers from TB. The group was especially concerned about the rise of multidrug-resistant tuberculosis, which would require more rigorous standards to mitigate, especially since they felt that the 1990 CDC guidelines for TB were not being properly followed. The CDC eventually revised and released new TB guidelines in 1994, and in 1995 and 1996, meetings started to be held between OSHA and various stakeholders for a new TB standard, borrowing heavily from the CDC's work.{{cite book|title=Introduction. Tuberculosis in the Workplace.|chapter=Introduction |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK222466/|publisher=National Academies Press (US)|date=2001}}

In 1997, OSHA proposed new rule changes for industries affected by the spread of tuberculosis, like hospitals, where many patients infected with TB were also infected with HIV. The proposed rule would require signage that includes a STOP sign, with red background, white symbols, and a set of words warning people to wear "N95 or more protective" respirators (under 42 CFR 84) near isolation rooms where TB infection is likely. Additional notices could be added at the discretion of an employer, so long as it did not contradict the required wording.

OSHA withdrew the proposal in 2003, owing to commenters and reviewers pointing to a likely overstating of risk, declining rates of TB in the years following the proposal, as well as compliance without a rule by OSHA.{{ran|C7}}

{{excerpt|Respirator|Continuing mesothelioma litigation|only=paragraphs}}

{{see also|2002–2004 SARS outbreak}}

File:SARS 2003 lab worker.png]]

In 2003, in response to the SARS outbreak, the United States CDC advised healthcare workers to wear N95 respirators.{{cite web|url=https://slate.com/news-and-politics/2003/04/do-surgical-masks-stop-sars.html|title=Do Surgical Masks Stop SARS?|first=Jon|last=Coen|date=7 April 2003|publisher=Slate}} Despite this advice, a patient who had traveled from Ontario exposed six healthcare workers in Pennsylvania following contact tracing by the CDC, though fitted N95 respirators were worn at a hospital upon suspicion of SARS.{{cite web|url=https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5216a1.htm|title=Update: Severe Acute Respiratory Syndrome --- United States, 2003|publisher=CDC MMWR Weekly|date=2003-04-25}}

Following the SARS outbreak in the US, US Senate hearings started to be held proposing the Strategic National Stockpile start stocking PPE and N95 respirators in the event of another SARS outbreak. It was noted at the time that there were few N95 respirator manufacturers, potentially exacerbating a shortage in a crisis.{{cite web|url=https://www.cidrap.umn.edu/sars/national-stockpile-sars-safety-gear-proposed|title=National stockpile of SARS safety gear proposed|first=Robert|last=Roos|date=2003-10-08|publisher=University of Minnesota CIDRAP News}}

Meanwhile, in Canada, discussions with Ontario EMS and New York Department of Health in 2004 noted that infected emergency medical personnel failed to properly use N95 respirators.{{cite web|url=https://www.health.ny.gov/professionals/ems/pdf/04-01.pdf|title=Re. SARS Advisory|date=10 February 2004}} According to Ontario SARS commission final report, this was likely due to confusion over infectious disease control, confusion over respirator procedures, and the insinuation by various infection control practitioners that N95 respirators were not necessary. However, the report concludes, from laws preceding SARS, healthcare workers were obligated to wear N95 respirators throughout the outbreak, despite suggestions to the contrary.{{citation |url=https://www.archives.gov.on.ca/en/e_records/sars/report/v3-pdf/Vol3Chp8.pdf|title=SARS Commission Final Report |volume= Three: Spring of Fear |date=2006 |chapter= Chapter Eight: It’s Not About the Mask |pages=1042–1154}}{{page needed|date=April 2025}} A paper published in the New England Journal of Medicine concluded that universal use of N95 respirators, as well as additional infection control measures, ended the SARS outbreak in Ontario.{{cite journal | url=https://doi.org/10.1056/NEJMoa032111 | doi=10.1056/NEJMoa032111 | title=Public Health Measures to Control the Spread of the Severe Acute Respiratory Syndrome during the Outbreak in Toronto | date=2004 | last1=Svoboda | first1=Tomislav | last2=Henry | first2=Bonnie | last3=Shulman | first3=Leslie | last4=Kennedy | first4=Erin | last5=Rea | first5=Elizabeth | last6=Ng | first6=Wil | last7=Wallington | first7=Tamara | last8=Yaffe | first8=Barbara | last9=Gournis | first9=Effie | last10=Vicencio | first10=Elisa | last11=Basrur | first11=Sheela | last12=Glazier | first12=Richard H. | journal=New England Journal of Medicine | volume=350 | issue=23 | pages=2352–2361 | pmid=15175437 | url-access=subscription }}

{{excerpt|Source control (respiratory disease)|Pre-COVID|only=paragraphs}}

===H1N1 swine flu pandemic===

{{see also|2009 swine flu pandemic}}

In May 2009, in response to the H1N1 swine flu outbreak, the CDC authorized the release of N95 respirators from the Strategic National Stockpile, and the waiving of certain quality controls on certain models of newly manufactured N95 respirators, provided they were documented "for use during the swine flu emergency".{{cite web|url=https://biotech.law.lsu.edu/blaw/H1N1-2009/N95-authorization.pdf|title=N95-authorization.PDF|date=2009-05-01|publisher=DHHS|access-date=2024-06-17}} Initially, the CDC's interim guide for H1N1 recommended N95 respirators for the prevention of H1N1, but stopped short of recommending respirators for groups not deemed "at increased risk of severe illness from influenza", except for occupational use in healthcare.{{cite web|url=http://www.cdc.gov/h1n1flu/masks.htm|title=Interim Recommendations for Facemask and Respirator Use to Reduce Novel Influenza A (H1N1) Virus Transmission|date=2009-05-08|archive-url=https://web.archive.org/web/20090901085143/http://www.cdc.gov/h1n1flu/masks.htm|archive-date=2009-09-01|publisher=CDC}} NIOSH also emphasized the differences in fit between an N95 respirator and a surgical mask for prevention against the flu.{{cite web|url=https://blogs.cdc.gov/niosh-science-blog/2009/10/14/n95/|title=N95 Respirators and Surgical Masks|date=14 October 2009|first1=Lisa|last1=Brosseau|first2=Roland Berry|last2=Ann}}

For those in the general public wishing to wear N95 respirators, properly wearing a N95 was noted to be difficult, but the tendency for people to distance themselves from those wearing masks was said to compliment the six-foot social distancing rules at the time.{{cite web|url=https://www.npr.org/2009/05/04/103789700/do-face-masks-protect-from-flu|title=Do Face Masks Protect From Flu?|first=Aubrey|last=Allison|publisher=NPR|date=4 May 2009}}

Around the time of the H1N1 pandemic, randomized control trial studies of masks started being done, comparing surgical masks and N95 respirators with the tendency for medical staff to be infected by the flu. One paper concluded that N95s were better than surgical masks, but its results were later called into question.{{cite web|url=https://www.cnn.com/2009/HEALTH/11/06/face.mask.swine.flu/index.html#:~:text=%22Based%20on%20all%20the%20available,respiratory%20protection%2C%22%20she%20says.|title=Respirator or face mask? Best H1N1 protection still debated|last=Pallarito|first=Karen|date=6 November 2009|publisher=Health.com}} Another paper claimed that protection provided by an N95 respirator compared similarly to a surgical mask, but the study did not control health care personnel potentially being exposed outside, without respirators, via the community.{{cite journal | url=https://doi.org/doi:10.1001/jama.2009.1466 | doi=10.1001/jama.2009.1466 | title=Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers | date=2009 | last1=Loeb | first1=Mark | last2=Dafoe | first2=Nancy | last3=Mahony | first3=James | last4=John | first4=Michael | last5=Sarabia | first5=Alicia | last6=Glavin | first6=Verne | last7=Webby | first7=Richard | last8=Smieja | first8=Marek | last9=Earn | first9=David J. D. | last10=Chong | first10=Sylvia | last11=Webb | first11=Ashley | last12=Walter | first12=Stephen D. | journal=JAMA | volume=302 | issue=17 | pages=1865–1871 | pmid=19797474 | url-access=subscription }}{{efn|A later preprint study by the same lead author (Loeb) claiming the same thing was found to be fraudulent in multiple ways, including use of unregistered study sites, repeated alteration of mathematical analysis methods to obscure the evidence in the data, as well as concealment of conflicts of interest; the actual data in that study showed that N95s were superior.{{cite web|url=https://osf.io/preprints/metaarxiv/ey7bj | title="Medical masks versus N95 respirators for preventing COVID-19 among health care workers: A secondary analysis of findings inconsistent with prior understanding reflects the expected inferiority of medical masks" | last1=Ungrin | first1=Mark}}}}

After the 2009 H1N1 flu season, the CDC issued guidelines recommending surgical masks instead, after complaints were leveled by various groups on the effectiveness of surgical masks compared to N95 respirators, along with complaints about comfort. The new recommendations were met with approval by groups like the Society for Healthcare Epidemiology of America.{{cite web|url=https://www.cidrap.umn.edu/influenza-general/cdc-finalizes-flu-prevention-guidance-health-settings|title=CDC finalizes flu prevention guidance for health settings|date=20 September 2010|last=Schnirring|first=Lisa|publisher=University of Minnesota CIDRAP News}}The Society for Healthcare Epidemiology of America's letter to President Obama: {{cite web|url=https://www.idsociety.org/globalassets/idsa/policy--advocacy/current_topics_and_issues/infection-prevention--control/comments/1100509-shea-idsa-apic-letter-re-ppe-guidance.pdf|title=SHEA-IDSA-APIC Letter on Federal PPE Guidance|date=2009-11-05|publisher=The Society for Healthcare Epidemiology of America|url-status=dead|archive-url=https://web.archive.org/web/20241208065259/https://www.idsociety.org/globalassets/idsa/policy--advocacy/current_topics_and_issues/infection-prevention--control/comments/1100509-shea-idsa-apic-letter-re-ppe-guidance.pdf|archive-date=2024-12-08}}

===COVID-19 pandemic===

{{see also|COVID-19 pandemic}}

File:200330-N-PH222-1167 (49720876783).jpg]]

File:Kimberly-clark_small_duckbill_n95_respirator.png

During the COVID-19 pandemic, the mask and respirator market rapidly grew, along with counterfeit respirators.{{cite web|title=From Scarcity to Abundance: Complementary Government and Private Initiatives to Manage the Allocation of N95 Masks in the U.S. During the COVID-19 Pandemic|url=https://economics.mit.edu/sites/default/files/2022-09/From%20Scarcity%20to%20Abundance%20%20Government%20and%20Private%20Initiatives%20to%20Allocate%20N95%20Masks%20During%20the%20COVID-19%20Pandemic%20in%20the%20U.S..pdf|first=Paul L.|last=Joskow|date=27 February 2022}} NIOSH, on behalf of the Department of Health and Human Services, filed a trademark application on June 17, 2020, for various 42 CFR 84 trademarks, including the N95, allowing NIOSH to enforce rules on counterfeit masks outside of rules defined in 42 CFR 84.{{cite web|url=https://tsdr.uspto.gov/#caseNumber=90006709&caseSearchType=US_APPLICATION&caseType=DEFAULT&searchType=statusSearch|title=Trademark Status & Document Retrieval|at=90006709}} The trademarks were registered in 2022.{{cite web|url=https://www.aiha.org/news/220120-niosh-registers-respirator-certification-marks-with-patent-and-trademark-office|title=NIOSH Registers Respirator Certification Marks with Patent and Trademark Office|date=20 January 2022|publisher=American Industrial Hygiene Association}}

{{Main|Face masks during the COVID-19 pandemic#N95 and FFP masks}}

The Strategic National Stockpile had not been refilled following the H1N1 pandemic,{{cite web|url=https://www.pbs.org/wgbh/frontline/article/depleted-national-stockpile-contributed-to-covid-ppe-shortage/|title=Depleted National Stockpile Contributed to COVID PPE Shortage: 'You Can't Be Prepared If You're Not Funded to Be Prepared'|first=Patrice|last=Taddonio|publisher=PBS Frontline|date=2020-10-06}} and by April 2020, Department of Homeland Security officials reported that the supply of respirators and other PPE in the stockpile was nearly gone.{{cite news|url=https://www.washingtonpost.com/national/coronavirus-protective-gear-stockpile-depleted/2020/04/01/44d6592a-741f-11ea-ae50-7148009252e3_story.html|title=Protective gear in national stockpile is nearly depleted, DHS officials say|first=Nick|last=Miroff|newspaper=The Washington Post|date=2020-04-02}} Respirators came to be in short supply and high demand during the COVID-19 pandemic, causing price gouging and hoarding, often leading to confiscation of masks.{{Cite web|url=https://thehill.com/policy/healthcare/public-global-health/489782-feds-have-15-million-expired-n95-masks-in-storage|title=Feds have 1.5 million expired N95 masks in storage despite CDC clearing them for use on COVID-19: report|last=Johnson|first=Martin|date=March 26, 2020|website=The Hill|df=mdy-all}}{{Cite news|last=Nicas|first=Jack|url=https://www.nytimes.com/2020/04/03/technology/coronavirus-masks-shortage.html|title=It's Bedlam in the Mask Market, as Profiteers Out-Hustle Good Samaritans|date=2020-04-03|work=The New York Times|access-date=2020-04-16|language=en-US|issn=0362-4331|df=mdy-all}}{{cite web | publisher=Hearst Television | title=3 million masks ordered by Massachusetts were confiscated in Port of New York, leading to creative alternative | website=WCVB | date=2020-04-03 | url=https://www.wcvb.com/article/3-million-masks-ordered-by-massachusetts-were-confiscated-in-port-of-new-york/32021700 | access-date=2020-04-16|df=mdy-all}} Production of N95 respirators was limited due to constraints on the supply of nonwoven polypropylene fabric as well as the cessation of exports from China.{{Cite news|last=Xie|first=John|url=https://www.voanews.com/a/science-health_coronavirus-outbreak_world-depends-china-face-masks-can-country-deliver/6186071.html|title=World Depends on China for Face Masks But Can Country Deliver?|date=2020-03-19|newspaper=Voice of America|df=mdy-all}}{{Cite news|first1=Melanie |last1= Evan|first2=Austen |last2=Hufford |title= Critical Component of Protective Masks in Short Supply |newspaper=The Wall Street Journal|date=March 7, 2020 |url= https://www.wsj.com/articles/coronavirus-pressures-supply-chain-for-protective-masks-11583552527 }}

Also in early April 2020, the United States federal government, invoking the Defense Production Act of 1950, ordered 3M to stop exporting N95 respirators to customers in Canada and Latin America, and to keep them within the U.S. instead. However, 3M refused, saying: "Ceasing all export of respirators produced in the United States would likely cause other countries to retaliate and do the same, as some have already done. If that were to occur, the net number of respirators being made available to the United States would actually decrease. That is the opposite of what we and the administration, on behalf of the American people, both seek."{{cite news |last1=Evans |first1=Pete |title=3M faces pressure from Trump order to stop exporting N95 masks to Canada |url=https://www.cbc.ca/news/business/3m-n95-masks-1.5520326 |access-date=26 October 2020 |publisher=CBC |date=2020|df=mdy-all}}

{{excerpt|Source control (respiratory disease)|Post-2023|only=paragraphs}}

Following previous H1N1 randomized control trials comparing N95s and surgical masks, new RCTs were published. Major flaws were noted, including contraction of virus outside hospital, the lack of controls over time in hospital, and assumptions made about transmission via droplets instead of aerosols.{{cite web|url=https://www.cidrap.umn.edu/covid-19/study-masks-vs-n95-respirators-health-workers-spurs-concerns|title=Study on masks vs N95 respirators for health workers spurs concerns|date=29 November 2022|publisher=University of Minnesota CIDRAP News}}

In addition, in 2024, a paper published in the American Society for Microbiology Clinical Microbiology Reviews stated there were harms in continued undue weight being placed on RCTs and flawed mask studies in a social and political context, as retracted papers continue to be circulated to justify certain masking behaviors and beliefs. One retracted JAMA paper{{cite journal | url=https://doi.org/10.1001/jamapediatrics.2021.3252 | doi=10.1001/jamapediatrics.2021.3252 | title=Notice of Retraction. Walach H, et al. Experimental Assessment of Carbon Dioxide Content in Inhaled Air with or Without Face Masks in Healthy Children: A Randomized Clinical Trial. JAMA Pediatr. Published online June 30, 2021 | date=2021 | last1=Christakis | first1=Dimitri | last2=Fontanarosa | first2=Phil B. | journal=JAMA Pediatrics | volume=175 | issue=9 | pages=e213252 | pmid=34269801 }} garnered a million views, while another retracted paper in Frontiers Public Health{{cite journal | doi=10.3389/fpubh.2023.1221666 | doi-access=free | title=Retraction: Physio-metabolic and clinical consequences of wearing face masks—Systematic review with meta-analysis and comprehensive evaluation | journal=Frontiers in Public Health | date=2023 | volume=11 | pmid=37304106 | author1=Frontiers Editorial Office | pmc=10251234 | bibcode=2023FrPH...1121666F }} continues to circulate across social media.{{cite journal | url=https://doi.org/10.1128/cmr.00124-23 | doi=10.1128/cmr.00124-23 | title=Masks and respirators for prevention of respiratory infections: A state of the science review | date=2024 | last1=Greenhalgh | first1=Trisha | last2=MacIntyre | first2=C. Raina | last3=Baker | first3=Michael G. | last4=Bhattacharjee | first4=Shovon | last5=Chughtai | first5=Abrar A. | last6=Fisman | first6=David | last7=Kunasekaran | first7=Mohana | last8=Kvalsvig | first8=Amanda | last9=Lupton | first9=Deborah | last10=Oliver | first10=Matt | last11=Tawfiq | first11=Essa | last12=Ungrin | first12=Mark | last13=Vipond | first13=Joe | journal=Clinical Microbiology Reviews | volume=37 | issue=2 | pages=e0012423 | pmid=38775460 | pmc=11326136 | hdl=1959.4/102268 }}

{{see also|2020–2024 H5N1 outbreak#United States}}

The CDC recommends farm workers wear PPE, including N95 or better respirators, when working with farm animals potentially infected with H5N1.{{cite web|url=https://www.cdc.gov/bird-flu/spotlights/hpai-health-recommendations.html?CDC_AAref_Val=https://www.cdc.gov/flu/avianflu/hpai/hpai-health-recommendations.html|title=Key Public Health Prevention Recommendations for HPAI A(H5N1)|date=June 10, 2024 |publisher=United States CDC|access-date=2024-06-15}}{{cite web|url=https://www.cdc.gov/flu/pdf/avianflu/protect-yourself-h5n1.pdf|title=Protect Yourself From H5N1 When Working With Farm Animals|publisher=United States CDC|access-date=2024-06-15}} However, outbreaks of H5N1 have continued among dairy workers, likely due to workers' fear of retaliation by their employers, and reluctance by employers and state officials to allow CDC investigators into dairy farms.{{cite web|url=https://www.bloomberg.com/news/articles/2024-05-08/us-bird-flu-risk-1-human-case-reported-more-likely-to-follow|title=Just One Human Is Infected by Bird Flu in the US. More Cases Are Likely|publisher=Bloomberg|date=8 May 2024|first1=Jessica|last1=Nix|first2=Riley|last2=Griffin|first3=Jason|last3=Gale}}

• Air purifier
• Corsi–Rosenthal Box
• Division of Industrial Hygiene
• Health belief model
• NIOSH
• Respirator assigned protection factors
• Permissible exposure limit
• Source control (respiratory disease)
• Toxic tort
• Face masks during the COVID-19 pandemic
• Face masks during the COVID-19 pandemic in the United States
• Impact of the COVID-19 pandemic on neurological, psychological and other mental health outcomes
• Workplace hazard controls for COVID-19

File:P100 respirator label.jpg-provided example of P100 respirator limitations]]

{{Notelist}}

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{{Reflist}}

{{refbegin |colwidth=30em}}

{{rma |tag=C1 |reference={{citation|url=https://www.govinfo.gov/content/pkg/FR-1994-05-24/pdf/FR-1994-05-24.pdf|title=Federal Register |volume=59 |issue=99 |date=1994-05-24 |pages=26850–26893}}}}

{{rma |tag=C3 |reference={{citation|url=https://archives.federalregister.gov/issue_slice/1994/10/28/54237-54364.pdf|title=Federal Register |volume=59 |issue=208 |pages=54237–54364}}}}

{{rma |tag=C4 |reference={{citation|url=https://www.govinfo.gov/content/pkg/FR-1995-06-08/pdf/95-13287.pdf| title=Federal Register |volume=60 |issue=110 |date=1995-06-08 |pages=30336–30397}}}}

{{rma |tag=C5 |reference={{cite wikisource|wslink=29 CFR 1910.134 Appendix D |title=29 CFR 1910.134 Appendix D}}}}

{{rma |tag=C7 |reference={{citation|url=https://www.osha.gov/laws-regs/federalregister/2003-12-31-0|title=Federal Register |volume=68 |issue=250 |date=2003-12-31 |via=OSHA}}}}

{{refend}}

{{refbegin |colwidth=30em}}

{{rma |tag=N2 |reference={{cite wikisource|wslink=NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84 | title=NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84 | date=January 1996 |scan=Index:DHHS Pub 96-101 NIOSH Guide to the Selection & Use of Particulate Respirators Certified Under 42 CFR 84.pdf |publisher=NIOSH}}}}

{{refend}}

{{refbegin |colwidth=30em}}

{{rma |tag=S1 |reference={{cite web|url=https://law.resource.org/pub/us/cfr/ibr/002/ansi.z88.2.1992.pdf|title=ANSI Z88.2: American National Standard for Respiratory Protection|date=1992-08-06}}}}

{{rma |tag=S3 |reference={{cite web|url=https://laws-lois.justice.gc.ca/PDF/SOR-86-304.pdf|title=Canada Occupational Health and Safety Regulations SOR/86-304|date=2024-12-15 }}}}

{{refend}}

{{Wikisource-multi|NIOSH Change Will Save Health Care Industry Millions|Differences and Limitations Between Part 11 Particulate Respirators and Part 84 Particulate Respirators|NIOSH Recommended Guidelines for Personal Respiratory Protection of Workers in Health-Care Facilities Potentially Exposed to Tuberculosis}}

{{Commons-inline|list= Respiratory Protection for Healthcare Workers Training Video (2012) }}

{{refbegin}}

• {{cite web |url=https://document.airnow.gov/wildfire-smoke-guide.pdf |title=Wildfire Smoke: A Guide for Public Health Officials Revised 2019 |date=September 2021 |publisher=US EPA}}
• {{cite journal | url=https://doi.org/10.1080/00028899908984440 | doi=10.1080/00028899908984440 | title=Compliance with OSHA's Respiratory Protection Standard in Hospitals | date=1999 | last1=Krishnan | first1=Usha | last2=Janicak | first2=Christopher A. | journal=American Industrial Hygiene Association Journal | volume=60 | issue=2 | pages=228–234 | pmid=10222573 | url-access=subscription }}
• {{cite journal | first1=Victor E. | last1=Schwartz | first2=Cary | last2=Silverman | first3=Christopher E. | last3=Appel. | title=Respirators to the Rescue: Why Tort Law Should Encourage, Not Deter, the Manufacture of Products that Make Us Safer. | journal=Am. J. Trial Advoc. | volume=33 | issue=13 | date=2009 | url=https://www.shb.com/-/media/files/professionals/s/silvermancary/respiratorstotherescue.pdf}}
• {{cite court |litigants=3M COMPANY f/k/a MINNESOTA MINING AND MANUFACTURING COMPANY v. SIMEON JOHNSON, JAMES CURRY, BOBBY JOE LAWRENCE AND PHILLIP PATE |court=Supreme Court of Mississippi |date=2002-01-30 |url=https://courts.ms.gov/images/OPINIONS/CO23457.PDF |quote=dismissed with prejudice |reporter=2002-CA-01651-SCT }}

{{refend}}

{{Commons category|42 CFR Part 84|position=right}}

• (United States) eCFR complete text of [https://www.ecfr.gov/current/title-42/chapter-I/subchapter-G/part-84 42 CFR 84]
• (Canada) Statutory Orders and Regulations text of [https://laws-lois.justice.gc.ca/eng/regulations/sor-86-304/page-24.html#h-895137 SOR/86-304]
• [https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question-and-answers-hub/q-a-detail/q-a-on-covid-19-and-masks Q & A—Masks and COVID-19] by the WHO
• [https://wwwn.cdc.gov/niosh-cel/ NIOSH Certified Equipment List]

{{Tuberculosis|state=collapsed}}

{{Breathing apparatus|industrial|state=expanded}}

{{Concepts in infectious disease|state=expanded}}

Category:1995 introductions

Category:Medical masks

Category:Respirators

Category:Medical hygiene

Category:Medical devices

Category:Occupational safety and health

Category:National Institute for Occupational Safety and Health