N95 respirator
An N95 mask or N95 respirator is a particulate respirator with a filter that meets the N95 NIOSH air filtration rating, meaning that it filters at least 95% of airborne particles but is not resistant to oil. It is the most common particulate filtering facepiece respirator.[1] This kind of respirator protects against particulates, but not gases or vapors.[2]
N95 respirators are considered functionally equivalent to certain respirators regulated under different jurisdictions, such as FFP2 respirators of the European Union and KN95 respirators of China. However, slightly different criteria are used to certify their performance, such as the filter efficiency, test agent and flow rate, and permissible pressure drop.[3][4]
The N95 mask requires a fine mesh of synthetic polymer fibers produced through a highly specialized process called melt blowing that forms the inner filtration layer that filters out hazardous particles.[5]
Usage
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. It is important to note that surgical masks are different than respirators and are not designed nor approved to provide protection against airborne particles because they do not form an adequate seal to the wearer's face to be relied upon for respiratory protection.[6]
Fit testing is a critical component to a respiratory protection program whenever workers use tight-fitting respirators. OSHA 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 N95s, require a user seal check each time one is put on.[6]
Use during shortages
Under serious outbreak conditions in which respirator supplies are severely limited, workers should work with their employer to choose the respirator that fits best, as, even without fit testing, a respirator will provide better protection than a surgical mask or no mask. In this case best practices include trying different models or sizes to get a good face seal, checking manufacturer training videos and literature on proper donning and doffing, doing a user seal check several times, and check the fit in a mirror or ask a colleague to look to be sure the respirator is touching the face.[6]
During crisis situations where there is a shortage of N95 respirators, such as the 2019–20 coronavirus pandemic, the U.S. Centers for Disease Control and Prevention (CDC) has recommended strategies for optimizing their use in healthcare settings.[4] N95 respirators can be used beyond their manufacturer-designated shelf life, although components such as the straps and nose bridge material may degrade, which can affect the quality of the fit and seal, making it particularly important that the wearer perform the expected seal check.[4][7] Respirators can be used that are approved under standards used in other countries that are similar to NIOSH-approved N95 respirators, including FFP2 and FFP3 respirators regulated by the European Union.[4] 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, although this increases the risk of surface contamination with pathogens. The respirator manufacturer may recommend maximum number of donnings or uses; if no manufacturer guidance is available, preliminary data suggests limiting to five uses per device to ensure an adequate safety margin.[4][8]
When it is no longer possible for all healthcare workers to wear N95 respirators when caring for a COVID-19 patient, respirators should 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 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; caution should be exercised when considering this option.[4]
Given that the global supply of personal protective equipment (PPE) is insufficient during the pandemic, the World Health Organization recommends 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.[9]
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.[10][11][12] 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.[13][14][15] Battelle received an Emergency Use Authorization from the U.S. Food and Drug Administration to sterilize N95 masks.[16][17] OSHA does not currently have any standards for disinfecting N95 masks.[11] 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.[8]
Contrast with surgical mask
A surgical mask is a loose-fitting, disposable device that creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. If worn properly, a surgical mask is meant to help block large-particle droplets, splashes, sprays, or splatter that may contain viruses and bacteria. Surgical masks may also help reduce exposure of the wearer's saliva and respiratory secretions to others.[18]
A surgical mask, by design, does not filter or block very small particles in the air that may be transmitted by coughs, sneezes, or certain medical procedures. Surgical masks also do not provide complete protection from germs and other contaminants because of the loose fit between the surface of the face mask and the face.[18] Collection efficiency of surgical mask filters can range from less than 10% to nearly 90% for different manufacturers’ masks when measured using the test parameters for NIOSH certification. However, a study found that even for surgical masks with "good" filters, 80–100% of subjects failed an OSHA-accepted qualitative fit test, and a quantitative test showed 12–25% leakage.[19]
The U.S. Centers for Disease Control and Prevention recommends surgical masks in procedures where there can be an aerosol generation from the wearer, if small aerosols can produce a disease to the patient.[20] The CDC recommends the use of respirators with at least N95 certification to protect the wearer from inhalation of infectious particles inclduing Mycobacterium tuberculosis, Avian influenza, severe acute respiratory syndrome (SARS), pandemic influenza, and Ebola.[21] Some N95 respirators have been also cleared by the U.S. Food and Drug Administration as surgical are labeled "Surgical N95", and provide respiratory protection to the wearer as well.[22]
History
A predecessor of the N95 was a design by Doctor Lien-teh Wu who was working for the Chinese Imperial Court in the fall of 1910, which was the first that protected users from bacteria in empirical testing. Subsequent respirators were reusable but bulky and uncomfortable. In the 1970s, the Bureau of Mines and NIOSH developed standards for single-use respirators, and the first N95 respirator was developed by 3M and approved in 1972. While designed for industrial use, they were increasingly used in healthcare settings in the 1990s.[23] Many American companies stopped producing N95 masks in the 2000s due to litigation costs and foreign competition.[24]
The masks are in short supply and high demand during the current 2019–20 coronavirus pandemic.[25] Production of N95 masks has been limited due to constraints on the supply of nonwoven polypropylene fabric (which is used as the primary filter) as well the cessation of exports from China.[26][27] China controls 50% of global production of masks, and facing its own Coronavirus epidemic, has dedicated all its production for domestic use only allowing exports through government-allocated humanitarian assistance.[26]
References
- ^ "NIOSH-Approved N95 Particulate Filtering Facepiece Respirators - A Suppliers List". U.S. National Institute for Occupational Safety and Health. 2020-03-19. Retrieved 2020-03-27.
{{cite web}}: CS1 maint: url-status (link) - ^ "Respirator Trusted-Source: Selection FAQs". U.S. National Institute for Occupational Safety and Health. 2020-03-12. Retrieved 2020-03-28.
{{cite web}}: CS1 maint: url-status (link) - ^ "Comparison of FFP2, KN95, and N95 and Other Filtering Facepiece Respirator Classes" (PDF). 3M Technical Data Bulletin. 2020-01-01. Retrieved 2020-03-28.
{{cite web}}: CS1 maint: url-status (link) - ^ a b c d e f "Strategies for Optimizing the Supply of N95 Respirators: Crisis/Alternate Strategies". U.S. Centers for Disease Control and Prevention. 2020-03-17. Retrieved 2020-03-28.
{{cite web}}: CS1 maint: url-status (link)
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- ^ Feng, Emily (March 16, 2020). "COVID-19 Has Caused A Shortage Of Face Masks. But They're Surprisingly Hard To Make". NPR.
- ^ a b c D’Alessandro, Maryann M.; Cichowicz, Jaclyn Krah (2020-03-16). "Proper N95 Respirator Use for Respiratory Protection Preparedness". NIOSH Science Blog. Retrieved 2020-03-27.
{{cite web}}: CS1 maint: url-status (link) This article incorporates text from this source, which is in the public domain.
- ^ "Release of Stockpiled N95 Filtering Facepiece Respirators Beyond the Manufacturer-Designated Shelf Life: Considerations for the COVID-19 Response". U.S. Centers for Disease Control and Prevention. 2020-02-28. Retrieved 2020-03-28.
{{cite web}}: CS1 maint: url-status (link) - ^ a b "Recommended Guidance for Extended Use and Limited Reuse of N95 Filtering Facepiece Respirators in Healthcare Settings". U.S. National Institute for Occupational Safety and Health. 2020-03-27. Retrieved 2020-03-28.
{{cite web}}: CS1 maint: url-status (link) - ^ "Rational use of personal protective equipment for coronavirus disease 2019 (COVID-19)" (PDF). World Health Organization. 2020-02-27. Retrieved 2020-03-21.
{{cite web}}: CS1 maint: url-status (link) - ^ Viscusi, Dennis J.; Bergman, Michael S.; Eimer, Benjamin C.; Shaffer, Ronald E. (November 2009). "Evaluation of Five Decontamination Methods for Filtering Facepiece Respirators". Annals of Occupational Hygiene. 53 (8): 815–827. doi:10.1093/annhyg/mep070. ISSN 0003-4878. PMC 2781738. PMID 19805391.
- ^ a b "Addressing COVID-19 Face Mask Shortages". Stanford University School of Medicine. 2020-03-25. Retrieved 2020-03-27.
{{cite web}}: CS1 maint: url-status (link) - ^ March 2020, Rafi Letzter-Staff Writer 24. "Doctors scramble for best practices on reusing medical masks during shortage". livescience.com. Retrieved 2020-03-27.
{{cite web}}: CS1 maint: numeric names: authors list (link) - ^ "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" (PDF). Duke University. Retrieved 2020-03-28.
{{cite web}}: Cite uses deprecated parameter|authors=(help)CS1 maint: url-status (link) - ^ Andrew, Scottie (March 27, 2020). "Duke researchers are decontaminating N95 masks so doctors can reuse them to treat coronavirus patients". CNN.
- ^ Billman, Jeffrey C. (2020-03-26). "Duke Researchers Find Way to Decontaminate and Reuse N95 Masks, Possibly Alleviating Critical Shortfall". INDY Week. Retrieved 2020-03-27.
- ^ Schladen, Marty (2020-03-29). "FDA lifts restrictions on Ohio-based Battelle's mask-sterilizing technology amid coronavirus shortages". USA Today. Retrieved 2020-03-30.
{{cite web}}: CS1 maint: url-status (link) - ^ "COVID-19: Deploying a Critical New PPE Decontamination System". Battelle. 2020-03-29. Retrieved 2020-03-30.
{{cite web}}: CS1 maint: url-status (link) - ^ a b "N95 Respirators and Surgical Masks (Face Masks)". U.S. Food and Drug Administration. 2020-03-11. Retrieved 2020-03-28. This article incorporates text from this source, which is in the public domain.
- ^ Brosseau, Lisa; Ann, Roland Berry (2009-10-14). "N95 Respirators and Surgical Masks". NIOSH Science Blog. Retrieved 2020-03-28.
{{cite web}}: CS1 maint: url-status (link) This article incorporates text from this source, which is in the public domain.
- ^ "Isolation Precautions". U.S. Centers for Disease Control and Prevention. July 22, 2019. Retrieved February 9, 2020.
{{cite web}}: CS1 maint: url-status (link) - ^ 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings (PDF). U.S. Centers for Disease Control and Prevention. July 2019. pp. 55–56. Retrieved February 9, 2020.
{{cite book}}: CS1 maint: url-status (link) - ^ "Respirator Trusted-Source Information: Ancillary Respirator Information". U.S. National Institute for Occupational Safety and Health. 2018-01-26. Retrieved 12 February 2020.
{{cite web}}: CS1 maint: url-status (link) - ^ Wilson, Mark (2020-03-24). "The untold origin story of the N95 mask". Fast Company. Retrieved 2020-03-27.
- ^ Smith, Sandy (June 22, 2006). "Six Respirator Manufacturers Warn President of Shortage of Masks". EHS Today.
- ^ Johnson, Martin (March 26, 2020). "Feds have 1.5 million expired N95 masks in storage despite CDC clearing them for use on COVID-19: report". TheHill.
- ^ a b Zie, John (March 19, 2020). "World Depends on China for Face Masks But Can Country Deliver?". Voice of America.
- ^ Evan, Melanie; Hufford, Austen (March 7, 2020). "Critical Component of Protective Masks in Short Supply - The epidemic has driven up demand for material in N95 filters; 'everyone thinks there is this magic factory somewhere'". The Wall Street Journal.
