COVID-19: Interim Recommendations Concerning the Use of Expired N95 Masks

COVID-19 preventive measures in the workplace
These measures apply when sustained community transmission has been confirmed by public health authorities.
N95 masks generally have a shelf life of five years following the date of manufacture.

According to the Centers for Disease Control and Prevention (CDC), if there is a shortage of unexpired masks, expired N95 masks may be used in the context of the COVID‑19 pandemic in certain conditions (https://www.cdc.gov/coronavirus/2019-ncov/release-stockpiled-N95.html February 28, 2020) :

  • The elastic straps and nose clips can become degraded, compromising the mask’s seal. In some mask models, the filter material can also become degraded. It is consequently important to inspect and seal-check expired masks;
  • Storage (stockpiling) conditions for masks also need to be verified, as they must comply with manufacturer recommendations for storage conditions;
  • Employers must have a respiratory protection program in place that complies with Occupational Safety and Health Administration (OSHA) requirements.

Studies supporting this position

A series of studies of 10 major N95 mask stockpile facilities in regions across the United States conducted by the National Personal Protective Assessment Laboratory at the National Institute for Occupational Safety and Health (NIOSH) showed that some models of masks remain effective after their expiration date.

NIOSH tested the filtration performance and exhalation/inhalation resistance of 11 models of N95 masks between 5 and 13 years (8 to 12 years in the majority of cases) after manufacture. Between 172 and 602 masks per site (at least 300 masks at most sites) were tested at the 10 stockpile facilities. The project to test expired masks remains ongoing, but the 10 reports on outcomes at individual facilities are now available on the NIOSH website at https://www.cdc.gov/niosh/npptl/ppecase.html (March 1, 2020).

  • Based on testing, the models of expired masks recommended by the CDC for use after their expiration date are:
    • 3M 1860 (tested by NIOSH at 8 sites)1
    • 3M 1870 (tested at 3 sites)2
    • 3M 8210 (tested at 3 sites)2
    • 3M 9010 (tested at 3 sites)2
    • Gerson 1730 (testés dans 3 sites)2
    • Medline/Alpha Protech NON27501 (tested at 1 site)2
    • Moldex 1512 (tested at 1 site)2
    • Moldex 2201 (tested at 1 site)2
  • Testing has shown that the following models of expired N95 masks exhibited lower performance and are not recommended:

    • Kimberly-Clark 46827 (34/559 (6.1%) of expired masks of this model did not pass filtration performance criteria)3;
    • Kimberly-Clark 46727 (40/387 (10.3%) of expired masks from five different sites did not pass filtration performance criteria).

Other considerations

  • The CDC notes that before using expired N95&nbp;masks, it is important to inform users that the masks have expired and need to be inspected and seal-checked.
  • The CDC and Cal/OSHA recommend not using expired N95 masks during surgical procedures, as in the studies cited above, NIOSH did not test masks for fluid resistance or flammability, which are important characteristics in the surgical context.
  • Cal/OSHA recommends using unexpired masks for higher-risk situations and tasks (https://www.dir.ca.gov/dosh/Use-of-Respirator-Supplies.html (March 2020) and https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/FAQ-N95.aspx (updated March 10, 2020).
  • Cal/OSHA also recommends that expired masks be used only by those with lower or less frequent risk of exposure to the virus (e.g. general practitioners).
  • It is to be noted that the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) has never conducted performance tests on expired N95 masks. Quebec-specific data are not available in this regard.

Note: The preceding recommendations are based on the latest available information at the time of writing. The current situation and our knowledge concerning the SARS CoV 2 (COVID 19) virus are evolving rapidly, and the recommendations set out in this document are consequently subject to change.

References

 

Additional references proposed by the California Department of Public Health


1 It is to be noted concerning the 3M 1860 that 2/1,247 (0.16%) of expired masks from different sites did not pass filtration performance criteria on NIOSH tests.
2 All (100%) masks of this model tested passed filtration performance criteria on NIOSH tests.
3 All 34 masks that failed testing came from a single site; masks of the same model from the other six sites passed the tests.

Interim Recommendations Concerning the Use of Expired N95 Masks

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