Strategies for Optimizing the Supply of N95 Respirators

N95 respirators include standard and surgical N95 respirators. In the United States, all N95 respirators used in occupational settings are approved by the National Institute for Occupational Safety and Health (NIOSH) and used in accordance with OSHA standards.

A NIOSH-approved N95 respirator with an exhalation valve offers the same protection to the wearer as one that does not have a valve. As source control, findings from NIOSH research suggest that, even without covering the valve, N95 respirators with exhalation valves perform the same or better than surgical masks, procedure masks, cloth masks, or fabric coverings.

A surgical N95 respirator is a NIOSH-approved N95 respirator that also meets the FDA surgical mask requirements for fluid penetration, flammability, and biocompatibility. Surgical N95 respirators (sometimes called medical respirators) are recommended for use by HCP who need protection from both airborne and fluid hazards, such as splashes or sprays. In times of shortage, only HCP who are working in a sterile field or who may be exposed to splashes, sprays, or splatters of blood or body fluids should be provided these respirators. Other HCP can use standard N95 respirators. If surgical N95 respirators are not available, and there is a risk that the worker may be exposed to splashes, sprays, or splatters of blood or body fluids, then a faceshield or surgical facemask should be worn over the standard N95 respirator. Care should be taken not to compromise the fit of the respirator if a facemask is placed over the respirator.

Use NIOSH-approved alternatives to N95 respirators where feasible. These include other classes of filtering facepiece respirators, elastomeric half-mask and full facepiece air purifying respirators, and powered air purifying respirators (PAPRs). All of these alternatives will provide equivalent or higher protection than N95 respirators when properly worn. NIOSH maintains a searchable, online version of the certified equipment list identifying all NIOSH-approved respirators.

Every other NIOSH-approved filtering facepiece respirator is at least as protective as the N95. These include N99, N100, P95, P99, P100, R95, R99, and R100 (with or without an exhalation valve). On March 2, 2020, FDA issued an Emergency Use Authorization (EUA)external icon authorizing the use of certain NIOSH-approved respirator models in healthcare settings.

As source control, findings from NIOSH research suggest that all NIOSH-approved filtering facepiece respirators with exhalation valves, even without covering the valve, perform the same or better than surgical masks, procedure masks, cloth masks, or fabric. If there is a risk that the worker may be exposed to splashes, sprays, or splatters of blood or body fluids, then a faceshield or surgical facemask should be worn over the standard N95 respirator. Care should be taken not to compromise the fit of the respirator if a facemask is placed over the respirator.

Elastomeric respirators are half-facepiece or full-facepiece, tight-fitting respirators that are made of synthetic or rubber material permitting them to be repeatedly disinfected, cleaned, and reused. They are equipped with a replaceable particulate filter (N95, N99, N100, P95, P99, P100, R95, R99, or R100) and provide the same protection level as N95 respirators. Elastomeric respirators require annual fit testing. Elastomeric respirators with unfiltered exhalation valves should not be used in surgical settings due to concerns that air coming out of the exhalation valve may contaminate the sterile field. The NIOSH Certified Equipment List identifies the elastomeric respirators without exhalation valves or with filtered exhalation valves that may be used in surgical settings.

PAPRs are reusable respirators that are typically loose-fitting hoods or helmets. These respirators are battery-powered with a blower that pulls air through attached filters or cartridges. When equipped with a high-efficiency (HE) filter, they provide a higher level of protection than N95 respirators, as they are 99.97% efficient against 0.3 micron particles. Loose-fitting PAPRs do not require fit-testing and can be worn by people with facial hair. However, PAPRs should not be used in surgical settings due to concerns that the blower exhaust and exhaled air may contaminate the sterile field.

On March 28, 2020, FDA issued an update to address NIOSH-Approved Air Purifying Respirators for Use in Health Care Settings During Response to the COVID-19 Public Health Emergency. Facilities using elastomeric respirators and PAPRs should have up-to-date cleaning and disinfection procedures, which are an essential part of use for protection against infectious agents.

Currently, CDC recommends discharge of patients with suspected or confirmed SARS-CoV-2 infection when they are medically stable and have an appropriate home environment to which to return. CDC lists considerations for care at home in: Interim Guidance for Implementing Home Care of People Not Requiring Hospitalization for Coronavirus Disease 2019 (COVID-19). If patients cannot be discharged to home for social rather than medical reasons, public health officials might need to identify alternative non-hospital housing where those patients can convalesce.

Facilities can consider temporarily suspending annual fit testing of HCP in times of expected shortages. Important conditions include the HCP has undergone an initial fit test with the same model, style, and size and the HCP has been explained the importance of conducting a user seal check each time the respirator is put on and conducting a fit test if there are visual changes to the employee’s physical condition. In June 2021, OSHA published a COVID-19 Emergency Temporary Standard, including a Mini Respiratory Protection Program, which applies to situations in which respirators are not required. The Mini Respiratory Protection Program emphasizes the importance of conducting a user seal check each time the respirator is donned.

In times of anticipated shortages, surgical N95 respirators should be prioritized for those HCP who are recommended to wear them as respiratory protection when caring for patients. Surgical N95 respirators should not be used by HCP who are only using them for source control.

In times of anticipated shortage, consideration can be made to use N95 respirators beyond the manufacturer-designated shelf life. However, expired respirators might not perform to the requirements for which they were certified. Over time, components such as the strap and material may degrade, which can affect the quality of the fit and seal. Because of this, use of expired respirators could be prioritized for situations where HCP are NOT exposed to pathogens, such as training, fit testing, and source control. As expired respirators can still serve an important purpose, healthcare facilities should retain and reserve all N95 respirators during the pandemic.

Practices allowing extended use of N95 respirators as respiratory protection, when acceptable, can also be considered. The decision to implement policies that permit extended use of N95 respirators should be made by the professionals who manage the institution’s respiratory protection program, in consultation with their occupational health and infection control departments with input from the state/local public health departments. Beyond anticipated shortages, increased feasibility and practicality may also be considered in decisions to implement extended use for HCP who are sequentially caring for a large volume of patients with suspected or confirmed SARS-CoV-2, including those cohorted in a SARS-CoV-2 unit, those placed in quarantine, and residents on units impacted during a SARS-CoV-2 outbreak.

Extended use refers to the practice of wearing the same N95 respirator for repeated close contact encounters with several different patients, without removing the respirator between patient encounters. Extended use is well suited to situations wherein multiple patients with the same infectious disease diagnosis, whose care requires use of a respirator, are cohorted (e.g., housed on the same hospital unit such as a COVID-19 unit). It can also be considered for care of patients with tuberculosis, varicella, measles, and other infectious diseases where use of an N95 respirator or higher respirator is recommended.

When practicing extended use of N95 respirators over the course of a shift, considerations should include 1) the ability of the N95 respirator to retain its fit, 2) contamination concerns, 3) practical considerations (e.g., meal breaks), and 4) comfort of the user. N95 respirators should be discarded immediately after being removed. If removed for a meal break, the respirator should be discarded and a new respirator put on after the break. If it is necessary to re-use N95 respirators in addition to extended use, please see the re-use section under crisis capacity strategies below. N95 respirators should be discarded when contaminated with blood, respiratory or nasal secretions, or other bodily fluids from patients. HCP can consider using a face shield or surgical facemask over the respirator to reduce contamination of the respirator, especially during aerosol generating procedures or procedures that might generate splashes and sprays. It is not known how facemasks placed over the respirator can affect the fit so caution should be used.

Consideration can be made to use N95 respirators beyond the manufacturer-designated shelf life for care of patients with diseases for which a respirator is recommended during their care (e.g., COVID-19, tuberculosis, measles, and varicella). Many models found in U.S. stockpiles and stockpiles of healthcare facilities have been found to continue to perform in accordance with NIOSH performance standards. However, fluid resistance and flammability were not assessed. Use of the N95 respirators recommended in NIOSH’s Beyond Shelf Life/Stockpiled Assessment Results can be considered. It is optimal to use these respirators in the context of a respiratory protection program that includes medical evaluation, training, and fit testing. If used in healthcare delivery, it is particularly important that HCP perform the expected seal check, prior to entering a patient care area. CDC does not recommend using N95s beyond the manufacturer-designated shelf life in surgical settings. On March 2, 2020, FDA issued an Emergency Use Authorization (EUA) authorizing the use of certain NIOSH-approved respirator models in healthcare settings.  The EUA was reissued on July 12, 2021. Due to the increased availability of NIOSH-approved respirators, the FDA removed filtering facepiece respirators that were NIOSH-approved but have since passed the manufacturers’ recommended shelf life.

Other countries approve respirators for occupational use according to country-specific standards. These products are evaluated using some methods that are similar to those used by NIOSH. Some methods are different but are expected to provide protection similar to NIOSH-approved filtering facepiece and elastomeric respirators. Devices supplied by current NIOSH-approval holders producing respirators under the standards authorized in the listed countries below are expected to provide the protection indicated, given that a proper fit is achieved. Therefore, they are considered to be suitable alternatives to provide protection during the COVID-19 response when supplies are short. Within Tables 1 and 2, the country, conformity assessment standards, standards and guidance documents, acceptable product classification, and NIOSH classification are provided in alphabetical order. All of these respirators have protection factors of at least 10 in the countries listed below, as outlined in the standards and guidance documents specified.

Non-NIOSH approved products developed by manufacturers who are not NIOSH approval holders are expected to meet the performance requirements if they have been issued a certificate of approval by an accredited test laboratory indicating they conform to the standards below. Non-NIOSH-approved products developed by manufacturers who are not NIOSH approval holders should not be used when an N95 respirator is recommended to be worn. Visit Factors to Consider When Planning to Purchase Respirators from Another Country and the NIOSH Science Blog for additional information on understanding the use of imported Non-NIOSH-approved respirators.

Table 1. Respirators Approved Under Standards Used in Other Countries That Are Similar to NIOSH-Approved N95 Filtering Facepiece Respirators

Re-use refers to the practice of using the same N95 respirator by one HCP for multiple encounters with different patients but removing it (i.e. doffing) after each encounter. This practice is often referred to as “limited reuse” because restrictions are in place to limit the number of times the same respirator is reused.²

For pathogens for which contact transmission is not a concern, routine limited re-use of single-use  disposable respirators has been practiced for decades. For example, for tuberculosis prevention, a respirator classified as disposable can be reused by the same provider as long as the respirator maintains its structural and functional integrity. If reuse must be implemented in times of shortages, HCP could be encouraged to reuse their N95 respirators when caring for patients with tuberculosis disease first. Limited re-use of N95 respirators when caring for patients with SARS-CoV-2 infection might also become necessary. However, it is unknown what the potential contribution of contact transmission is for SARS-CoV-2, and caution should be used.

It is important to consult with the respirator manufacturer regarding the maximum number of donnings or uses they recommend for the N95 respirator model. If no manufacturer guidance is available, data suggest limiting the number of reuses to no more than five total uses (five total donnings) per device by the same HCP to ensure an adequate respirator performance.³ Example scenario: a HCP wears a respirator to care for a patient, removes it after exiting the room, and then later returns to care for the patient and puts the same respirator on again. This would count as two uses or donnings. HCP should always inspect the respirator and perform a seal check upon donning a re-used respirator.  N95 and other disposable respirators should not be shared by multiple HCP.

During times of crisis, practicing limited re-use while also implementing extended use can be considered. If limited re-use is practiced on top of extended use, caution should be used to minimize self-contamination and degradation of the respirator. If no manufacturer guidance is available, a reasonable limitation should continue to be five total donnings regardless of the number of hours the respirator is worn. Example scenario: An HCP wears a respirator during the first 3 hours of his or her shift, removes the respirator to eat lunch, and puts it back on after lunch. This would count as two uses or donnings.

N95 respirators should not be re-used when caring for patients with varicella or measles, as contact transmission poses a risk to HCP who implement this practice.

Respirators soiled or grossly contaminated with blood, respiratory or nasal secretions, or other bodily fluids from patients should be discarded. HCP can consider using a face shield over the respirator to reduce/prevent contamination of the N95 respirator, especially during aerosol generating procedures or procedures anticipated to generate splashes and sprays. It is important to perform hand hygiene before and after the previously worn N95 respirator is donned or adjusted.

The surfaces of a properly donned and functioning NIOSH-approved N95 respirator will become contaminated with pathogens while filtering the inhalation air of the wearer during exposures to pathogen laden aerosols. The pathogens on the filter materials of the respirator may be transferred to the wearer upon contact with the respirator during activities such as adjusting the respirator, improper doffing of the respirator, or when performing a user-seal check when redonning a previously worn respirator. One potentially effective strategy to mitigate the contact transfer of pathogens from the respirator to the wearer could be to issue each HCP who may be exposed to patients with SARS-CoV-2 infection a minimum of five respirators. Each respirator will be used on a particular day and stored in a breathable paper bag until the next week. This will result in each worker requiring a minimum of five N95 respirators if they put on, take off, care for them, and store them properly each day.  This amount of time in between uses should exceed the 72 hour expected survival time for SARS-CoV-2 (the virus that causes COVID-19).⁴ If this strategy is used, the total number of donnings should still not exceed five times before discarding the respirator, when no manufacturer instructions are provided to indicate otherwise.

Decontamination or bioburden reduction of NIOSH-approved N95 respirators is no longer a strategy to conserve supplies as the availability to NIOSH-approved respirators has significantly increased. In July 2021, the FDA removed the EUA of decontaminated respirators from the scope of authorization.

Use of additional N95 respirators beyond the manufacturer-designated shelf life for care of patients for whom a respirator is recommended during their care (e.g., SARS-CoV-2 infection, tuberculosis, measles, varicella) is no longer authorized as part of an FDA EUA. Some models have been found NOT to perform in accordance with NIOSH performances standards, and previous consideration was given to use these respirators as identified in Use of the N95 respirators recommended in NIOSH’s Beyond Shelf Life/Stockpiled Assessment Results.

The number of infectious particles required to cause an infection (infectious dose) is often uncertain or unknown for respiratory pathogens. Further, there is often uncertainty about the influence of factors such as exposure duration and nature of clinical symptoms on the likelihood of infection transmission from person-to-person.

Source control (i.e., masking of patients) and maintaining physical distance from the patient are particularly important to reduce the risk of transmission. This prioritization approach to conservation is intended to be used when N95 respirators are so limited that routinely practiced standards of care for all HCP wearing N95 respirators when caring for a patient with SARS-CoV-2 infection are no longer possible. N95 respirators beyond their manufacturer-designated shelf life, when available, are preferable to use of well-fitting facemasks. The use of N95s or elastomeric respirators or PAPRs should be prioritized for HCP with the highest potential exposures including being present in the room during aerosol generating procedures performed on persons with SARS-CoV-2 infection.

When facemasks must be used by HCP entering a patient care area, improving the fit of a facemask can reduce exposure to infectious particles. Options to improve the fit of a facemask are discussed in Improve How Your Mask Protects You, and include, but are not limited to selection of a facemask with ties rather than ear loops, use of a mask fitter, tying the facemask’s ear loops and tucking in the side pleats, fastening the facemask’s ear loops behind the wearer’s head, and using a cloth layer over the facemask to help it conform to the wearer’s face. Use of facemasks to care for a patient with suspected or confirmed SARS-CoV-2 infection should only be used as a last resort if respirators are severely limited.

Portable fan devices with high-efficiency particulate air (HEPA) filtration that are carefully placed can increase the effective air changes per hour of clean air to the patient room, reducing risk to individuals entering the room without respiratory protection. NIOSH has developed guidance for using portable HEPA filtration systems to create expedient patient isolation rooms. The expedient patient isolation room approach involves establishing a high-ventilation-rate, negative pressure, inner isolation zone that sits within a “clean” larger ventilated zone. In the absence of any remaining supply of N95 respirators, it may be possible to use this technology in conjunction with HCP wearing well-fitting facemasks.

NIOSH has developed the ventilated headboard that draws exhaled air from a patient in bed into a HEPA filter, decreasing risk of HCP exposure to patient-generated aerosol. This technology consists of lightweight, sturdy, and adjustable aluminum framing with a retractable plastic canopy. The ventilated headboard can be deployed in combination with HEPA fan/filter units to provide surge isolation capacity within a variety of environments, from traditional patient rooms to triage stations, and emergency medical shelters. In the absence of any remaining supply of N95 respirators, it may be possible to use this technology in conjunction with HCP and/or patients wearing well-fitting facemasks.