With the 9th month of the COVID-19 pandemic, one of the simplest medical devices is still out of reach: protective facemasks of the medical level, generally built and equipped for one-use purposes only. Chinese and U.S. engineers are now designing innovative methods to decontaminate and reuse masks that hospitals are already in charge to fulfil the crucial and increasingly growing demand. Several of these techniques require special equipment while some are relatively easy to use at home.
CDC's N95 FFR Supply Optimisation Strategies were established with a view to continuum using the traditional surge capacity approach, contingency and crisis. After each use, N95 FFRs should be disposed of. To help health facilities maintain their resources in the face of scarcity, the CDC has established emergency and crisis plans.
If the supply of N95 FFRs due to an anticipated shortage is limited, supplies should first be maintained by contingency strategies.
With extended use, N95 FFR is worn for a prolonged time before removing and replacing it for several patient contacts. This will slow down the N95 FFR burning rate to mitigate supply problems.
N95 masks are used for performance monitoring and training beyond the supplier's defined shelf-life.
Crash capacity strategies can be used following attempts of the above contingency strategies, and a documented lack of N95 FFRs and available resources can not satisfy needs based on the current burn rate.
Crisis Capacity Strategies
In addition to the manufacturer-designated health care product shelf life, respirators (including N95 FFRs and other types of respirators) are used.
Respirators are used that are identical to those approved by NIOSH but not approved by NIOSH and are licenced in other countries according to the requirements. NIOSH has tested the efficiency of some globally recognised breathing machines, and the findings are available here.
Respirators are used that have not been tested by NIOSH but have exceeded the specified shelf life of the product.
With minimal reuse, one patient contact receives an N95 FFR, then stores and processed for a minimal number of donations, before being used for other patients' communication.
The use of N95 facemasks is given priority by form.
The guidelines include specifications on a healthcare facility can function during the COVID-19 pandemic and how to properly reuse and reuse N95 FFRs after decontamination during N95 FFR disaster crises.
As after 72 hours, many organisations have advocated rotation and reuse strategy because coronaviruses are losing their viability significantly. The CDC suggests that masks can be re-used for five times under the following strategy if no grounding occurs and no viral contamination to masks.
CDC, mask firms and significant academic / industry partners are currently researching mask decontamination techniques. Specific re-processing criteria include:
- The mechanism needs to disable the viral load on the mask adequately.
- The mask can not be soiled.
- As far as possible, filtration capability and electrostatic charging must be -maintained.
- There is no compromise on the fit of the mask.
Most experiments have been conducted with flu virus or bacterial spores on N95 decontamination and thorough extrapolation to the present pandemic. Fortunately, newly published SARS-CoV-2 investigations have explicitly begun, and positive results have been found.
Here is a concise description of the existing evidence assisted decontamination processes. Because of the pace of the study, some papers have not yet been reviewed by peers. Besides, note that N95 masks with different straps and shapes are available in several models. Therefore, for one mask form, one approach will work well, not for another one.
Hydrogen Peroxide Vaporization
In pilot studies, decontamination of hydrogen peroxide vapour (HPV) has been demonstrated to provide appropriate functional maintenance for multiple processing cycles of N95. It has now been authorised by FDA for emergency decontamination of N95 by medical workers during the pandemic of COVID-19. Only N95 models that do not include cellulose, for example, 1860 may use this decontamination process. It is utilised via the equipment of Sterrad or Steris in industrial installations such as Battelle and individual hospitals.
Proper N95 mask UV treatment requires specific protocols and maximum surface illumination to guarantee airborne particles with mask degradation are correctly deactivated. The use of UV light at home is not recommended because of the accuracy required. Some hospital systems in the United States have adopted this decontamination process.
The moist heat that is heating 60–70 and relative moisture 80–85% is sufficient for influenza viruses. Still, the temperature, moisture, and time data needed for the inactivation of the viral particles from the SARS-COV-2 were small. Besides, the parameters to kill the virus will affect the efficacy of mask filtration. This approach is not currently suggested because of the lack of clear data on a protocol to accomplish both purposes.
For 30 minutes, the dry heating of the mask with 70° C has been proposed to destroy viruses properly and maintain the integrity of the philtre for re-use. The recent NIH tests on SARS-CoV-2 showed that this approach can be used without compromising fit for two cycles to kill the virus. The efforts of the CDC are still underway to define optimal parameters.
For the re-use and re-processing of N95, there is no clear "best practise." These approaches are crisis options and should not be used regularly if an adequate supply of masks is required. The best strategy for every individual or organisation varies depending on the resources available in each organisation.