When should limited reuse be implemented?

Limited FFR reuse is just one of several strategies available for addressing an N95 FFR crisis capacity situation when there is a known shortage of devices after conventional and contingency capacity strategies have been implemented. It should only be considered during a crisis capacity situation during a declared public health emergency. When an N95 FFR crisis situation no longer exists, limited FFR reuse should not be utilized.

Before deciding to implement FFR reuse, facilities should explore opportunities to switch to respirators that are designed to be decontaminated and reused (e.g., elastomeric respirators or powered air-purifying respirators) to reduce demand for FFRs and the need for crisis capacity strategies.

Limitations for Limited FFR reuse

Decrease in N95 FFR fit and filtration performance

NIOSH-certified N95 FFRs are designed to filter 95% of particles when appropriately fitted to the wearer’s face. This means that an N95 that is not properly fitted to the face will likely give the wearer less protection. N95 FFRs are designed to be single-use devices but may be used multiple times under crisis capacity strategies. N95 FFR performance will decrease as the number of hours and number of donnings and doffings increase.

The number of times that an FFR can be reused will likely be limited by its fit because the tethering straps can become weaker or stretched after each donning. Each time an N95 FFR is donned or doffed, the integrity of the straps may be impacted. Repeated donning and doffing will result in the straps no longer being able to generate enough force to create a tight seal with the face. The resulting poor seal will allow unfiltered air to enter the N95 FFR and into the wearer’s breathing zone.

CDC recommends limiting the number of donnings for an N95 FFR to no more than five per device. It may be possible to don some models of FFRs more than five times [2]. One study reported that fit performance decreased over multiple, consecutive donnings and fit varied among the different models of FFRs examined [3]. If manufacturer guidance on how many times a particular FFR can be donned is not available, the CDC recommends limiting the number of uses to no more than five per device based on published data on changes in FFR fit from a limited number of FFR models over multiple donnings.

A recent observational study conducted in a hospital emergency room during the COVID-19 pandemic found that extended use and reuse of N95 FFRs as measured by the total hours and shifts the mask was worn and the number of donnings and doffings was associated with an increase in the fit failure of the respirators. This study also showed that it may be possible to don some models of FFRs more than five times [2]. Fit performance during limited reuse should be monitored by the respiratory protection program manager or appropriate safety personnel. Information about how to assess N95 FFR fit during limited reuse can be found below. More information on limited FFR reuse can be found here.