IRSST - Institut de recherche Robert-Sauvé en santé et en sécurité du travail

IRSST's Notices, Recommendations and Support Tools

The contribution of occupational health and safety (OHS) research to the fight against the COVID-19 pandemic.

Alternatives to N95 type respiratory protection equipment

N95 type respiratory protection equipment (RPE) is a disposable filtering facepiece with an assigned protection factor (APF) of 10. There are several other kinds of RPE that provide equivalent or greater protection. According to the CNESST, all RPE must be approved by the National Institute for Occupational Safety and Health (NIOSH). In addition, a respiratory protection program must be developed and applied for all RPE used by a worker. In case of a shortage of N95s, the US Centers for Disease Control and Prevention (CDC) raise the possibility of using RPE that have been approved by other international organizations1. The employer must then check with the manufacturer, which must confirm the equivalence. If the model or type of RPE used by a worker must be changed, it is essential for training on the new equipment and fit tests to be done based on the regulatory requirements. It always remains necessary to check the seal at each use.

A list of the main classes of RPE available in Quebec follows:

  • Filtering facepieces: disposable half masks (N, P and R95; N, P and R99; N, P and R100).
  • Reusable elastomeric or silicone half masks or full masks with particle filters (non-powered air purification).
  • PAPR (Powered Air-Purifying Respirators): Powered air-purifying RPE that provides positive pressure in the worker’s respiratory zone. This equipment can be used with half masks or full masks, but also with non-hermetically sealed facepieces (helmet, hood or flexible mask/face shield). When used appropriately, this kind of RPE has a higher protection factor than non-powered air-purifying RPE (APF of 25 compared to APF of 10 for N95 RPE); moreover, it does not require seal and fit testing.

Although reusable RPE poses a cleaning problem2, it reduces procurement problems, because, if well maintained, it remains available to the worker over the long term. The workplace and the worker who has reusable RPE must be well trained on how to maintain, clean and store it. Particle filters (usually P100) for reusable half masks and full masks can be used over long periods, reducing the risks of shortage. However, contact contamination must be controlled by appropriate cleaning of their surfaces. In a period of shortage, the preference should be for particle filters encased in hard shells that can be disinfected3. All classes of particle filters can be used with reusable RPE. Note that RPE with exhalation valves cannot be used in operating rooms because the air exhaled by the wearer is not filtered.


In case of a shortage of disposable N95 type RPE, several other kinds of RPE can be used: disposable filtering facepieces (N, P and R95; N, P and R99; N, P and R100); reusable elastomeric half masks and full masks, and powered air-purifying RPE with non-hermetic facepieces of the hood or flexible mask/face shield type.

Extended use and reuse of N95 type RPE

To reduce the number of disposable N95 type RPE needed in case of a shortage, extended use of RPE can be considered. Extended use refers to the practice of wearing the same RPE for successive meetings with several patients without changing it between patients. This strategy can be implemented when several patients are infected with the same respiratory pathogen and they are in adjacent or nearby rooms. Extended use was recommended as an option to preserve RPE inventories during previous epidemics and pandemics4. In addition to protecting the health care worker, the use of a face shield can protect the RPE from splashes, which will make extended use easier. This strategy also has the advantage of protecting from aerosols at eye level. The use of a surgical mask over N95 type RPE is a practice that may be recommended to protect the RPE and facilitate extended use. A key consideration for safe extended use is that the RPE must necessarily keep a good seal throughout the duration of wear. As soon as a worker realizes that his/her RPE has a leak or a poor seal, he/she must immediately move away from the source and withdraw in order to change the RPE. The protocols for safe donning and doffing of RPE must be respected.

Extended use does not mean reuse, which involves doffing, storing and then reusing the RPE5. Reuse is not recommended in the case of infectious agents that are transmissible by contact. Limited reuse can be considered for certain workers who are not directly assigned to the treatment of contagious patients. As proposed in the case of extended use, wearing a procedure or surgical mask over N95 type equipment could prevent it from being soiled by splashing, which allows for limited reuse. This eventuality must not allow for any compromise concerning the seals of N95 type RPE, which must be maintained at all times. If a reuse policy is applied, the used RPE must be hung in a designated zone between uses or kept in a clean, breathable container, such as a paper bag.


  • If there is a shortage of N95 type RPE, an extended use strategy, rather than a reuse strategy, should be promoted in order to limit the risk of repeated contact between the RPE and the worker’s face.
  • Extended use or reuse must be prohibited in the case of aerosol-generating medical procedures (AGMPs).
  • As soon as an N95 type RPE becomes soiled, it must be disposed of.

Use of expired N95 type RPE

In an assessment by NIOSH of reserves of N95 type RPE more than five years old, the results showed that 1% of the disposable N95 that were tested failed the certification tests, presenting penetration levels of over 5% for the most penetrating particles (0.3 µm). The worst-performing N95 type RPE had a penetration level of 10%. Several of the failed RPE had penetration levels between 5% and 6%6.

Two actions must be taken to check the integrity of an expired N95. The physical appearance of the N95 must be meticulously examined to identify any possible physical degradation that would result in a loss of seal. If the N95 is not physically degraded, the worker must absolutely conduct a successful seal check. If the seal is not at the required level, the RPE must be disposed of and a new one must be used, after checking its seal.


In the event of a shortage of N95 type RPE, the use of an expired N95 would be preferable to the use of surgical masks or no RPE at all.

Additional information

Refer to the web tool designed by the IRSST to assist with RPE selection in order to find out about respiratory protection solutions against bioaerosols for workers.

In addition, France’s Institut national de recherche et de sécurité pour la prévention des accidents du travail et des maladies professionnelles (INRS) has published an article (in French) on seals for RPE. The INRS has also issued a fact sheet (in French) on the differences between RPE and surgical and/or procedure masks.

A production of Institut de recherche Robert-Sauvé en santé et en sécurité du travail

  • Geneviève Marchand, researcher, certified microbiologist and biochemist, IRSST
  • Maximilien Debia, researcher and associate professor, Department of environmental and workplace health, School of public health, Université de Montréal, Centre de recherche en santé publique (CReSP)
  • Loïc Wingert, scientific professional, IRSST
  • Alberto Morales, scientific professional and registered occupational hygienist (ROH), IRSST
  • Delphine Lanoie, microbiologist and scientific professional, IRSST

This notice has been prepared by the IRSST, in collaboration with its social partners, employer and worker representatives, and members of its Scientific Advisory Board.


1 [1] Centers for Disease Control and Prevention (CDC). Strategies for Optimizing the Supply of N95 Respirators: Crisis/Alternate Strategies (accessed on March 26, 2020).

2 [2] The IRSST has issued a procedure for the disinfection of reusable elastomeric masks available at

3 [3] Particle filters encased in a hard shell can be disinfected with moistened wipes such as isopropyl alcohol (55%) wipes.

4 [4] Rebmann, T., Alexander, S., Cain, T., Citarella, B., Cloughessy, M., Coll, B., … Wagner, W. (2009). APIC Position Paper: Extending the Use and/or Reusing Respiratory Protection in Healthcare Settings During Disasters:

5 [5] Centers for Disease Control and Prevention (CDC). March 27, 2020. Recommended Guidance for Extended Use and Limited Reuse of N95 Filtering Facepiece Respirators in Healthcare Settings: (accessed on April 6, 2020).

6 [6] Centers for Disease Control and Prevention (CDC). February 28, 2020. Release of Stockpiled N95 Filtering Facepiece Respirators Beyond the Manufacturer-Designated Shelf Life: Considerations for the COVID-19 Response: (accessed on March 26, 2020).