N95 masks

N95 Respirators & PPE:

Desperate Measures = Dangerous Outcomes

With the shortage of N95 respirators for our frontline healthcare workers, hospitals are resorting to the tools they have at hand without realizing they could be infecting rather than protecting their workers. While this may feel like uncharted waters for many healthcare facilities, there are existing studies, tools, and technologies to help guide these critical decisions.

Four things to consider when faced with a shortage of N95 respirators and other PPE:


1. Known challenges with N95 reuse

Under normal circumstances an N95 mask is intended for a single-use.  This is for good reason as single use protective gear is the simplest way for a hospital to maintain sterile conditions.  In the current situation we face the necessity of reusing these masks.  There are some inherent challenges to this, including though not limited to:

  • Achieving disinfection in a porous material
  • Achieving disinfection through possible biofilm
  • Possible degradation of the HEPA filter element
  • Strap degradation
  • Throughput time of disinfection & verification

2. Existing government guidelines

The government, in anticipation of a pandemic crisis, has already established guidelines to help in make the right choices in this time of crisis.  The Office of Public Health and Environmental Hazards convened a panel of medical experts for Project B.R.E.A.T.H.E. who concluded the following;

…during a crisis in which respirators may be in short supply, respirators that are durable enough to be repeatedly decontaminated (e.g., to render infectious materials on the respirator inactive and thus unable to act as a fomite) may be necessary…

OSHA: respirator cleaning procedures “must ensure that the respirator is properly cleaned and disinfected in a manner that prevents damage to the respirator and does not cause harm to the user”

FDA: For reprocessed single-use medical devices, the US Food and Drug Administration (FDA) requires validation data regarding cleaning, sterilization, and functional performance

Institute of Medicine: any method decontaminating a disposable N95 FFR must remove the pathogen, be harmless to the user, and not compromise the integrity of the various parts of the respirator.

The important take-away is that the experts have already made recommendations for how shortages of N95 respirators and PPE should be handled.  The message is clear, when needing to reuse N95 respirators…

They must be cleaned and disinfected
*EPA definition of disinfection is to demonstrate a 5-6 log reduction of an organism
The filter in the respirator must not be damaged by the process
*Proving 95%of the filter’s original capacity
There must be a way to prove disinfection has occurred
*Some sort of biological indicator or a way to prove a reduction of colony forming units
The method used should not cause harm to the user
*No chemicals used which could cause off gassing for the user to inhale
No degradation of materials in the mask
*Both mask and stray retain their ability to fit properly

3. Tools being used to decontaminate N95 Masks, some with mixed results


Aerosolized Hydrogen Peroxide:

This technology is capable of achieving a 99.9999% reduction of bacterial spores in multiple different applications, meaning less than one organism left behind

which permeates the layers of the mask to kills germs, including viruses, without degrading the mask material

Ethylene Oxide:

This gas is sometimes still found in use in the surgical area of the hospital.While it can achieve disinfection of a respirator, this gas is a known carcinogen & therefore a risky choice

UV Light:

This disinfecting light has a significant success when used directly on hard surfaces, however in this application still only achieves a 99.9% reduction, leaving behind 1,000 organisms to propagate

4. Studies that guide us to make the right choices

This 2018 study clearly shows UV treatment of N95 masks results in an insufficient reduction level for achieving decontamination: Ultraviolet germicidal irradiation of influenza-contaminated N95 filtering facepiece respirators https://www.sciencedirect.com/science/article/pii/S0196655318301408

This study proves hydrogen peroxide fogging will not be harmful to the N95 respirator: Evaluation of Five Decontamination Methods for Filtering Facepiece Respirators https://academic.oup.com/annweh/article/53/8/815/154763

This study proves the effectiveness of Hydrogen Peroxide fog in decontaminating HEPA filtration:  Effectiveness of Aerosolized Hydrogen Peroxide in Simultaneous Decontamination of a Laboratory and a Biological Safety Cabinet http://www.curissystem.com/effectiveness-of-aerosolized-h2o2-study/

Having now looked at each of these considerations we find a ray of hope in a seemingly bleak situation.  Given adherence to the established government guidelines, and following the proven science, we can see a clear solution of known technology emerge.  Hydrogen Peroxide fogging is a safe and proven method to employ as a solution to the critical shortage of N95 masks, proving a way to protect the health of the workers on the frontline of this pandemic.

Aerosolized H2O2 Fogging UV Light Ethylene Oxide
Cleaned & Disinfected X
Maintained integrity of filter ?
Proof of Disinfection X
No harm to user X
No degradation of respirator ?






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