I'm posting in its own thread because I think this could be helpful now that the CDC is recommending that people wear face protection. With the shortage of PPE impacting the medical community, having a viable decontamination method could elongate the usable life of critical equipment.
Does anybody have any materials research connections or contacts at 3M? I have a proposed decontamination method that could work for areas with less access to resources and also could be adapted to mitigate the "Fit" concern for disposable PPE
I've been doing as much reading on this topic that I can find (Even called a microbiology PhD Ag friend and emailed the authors of this paper https://elautoclave.files.wordpress.com/2020/03/stanford-2020.pdf).
First, Its important to state that Dr. Price and Dr. Chu's paper's specifically mentions that they have not tested the efficacy of these methods against decontaminating against COVID-19. They have simply been testing the integrity of the meltdown material in the N95 masks.
As their paper states, "To be useful a decontamination method must eliminate the viral threat, be harmless to end users, and retain respirator integrity." The paper summarizes, "70C/158F heating in an oven for 30 min... is an effective decontamination method". In an updated paper they increased the temperature to 75C. I thought of a possible "low tech" solution that could be leveraged in situations where specialized equipment is unavailable (ex. vacuum ovens or Vaporous Hydrogen Peroxide (VHP) autoclaves).
My proposed solution consists of placing an N95 mask in a vessel (ex. ziploc bag) and immersing in a water bath set to 75C(or higher) for 30 min (or longer)? Home chefs use this method often for cooking sous vide (under vacuum) and holding food at a set temperature for extended periods of time. The lower the temperature, the longer you have to hold to kill bacteria and viruses.
I think this method should also be tested by materials scientists to measure the impact to the meltblown fibers. Perhaps this water bath method would cause less damage to respirator integrity due to the nature of a gentle thermal load. Additionally, perhaps masks could be held at a lower temperature for longer periods of time, decreasing the impact to meltdown, elastic, and nose padding.
The Vacuum oven method mentioned in the Stanford paper requires that masks be placed on a rack or flat surface. One of the additional concerns the CDC and The National Institute for Occupational Safety and Health (NIOSH) mentions is the fit of the masks after multiple decontamination cycles. [url=https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html][/url]https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html
Additional considerations to the water bath method: Molds could be developed to place masks over before sealing in "the vessel" and immersed, essentially maintaining (or resetting) the masks shape and therefore its fit.
Vaporous Hydrogen peroxide (VHP) enclaves are probably a better solution but they are going to take some time to be available in other areas in the nation let alone globally. In poorer countries, they wont even have that as an option.
This method needs to be tested for impact to the meltdown material, needs to be researched on its impact to COVID-19, and needs to be run by manufacturers to see if the "mold" consideration can assist with fit concerns.
I'm asking for anybody's thoughts here on Texags. If you know someone who is in materials research and can weigh in or possibly know someone who is connected to 3M engineering, let me know.
Does anybody have any materials research connections or contacts at 3M? I have a proposed decontamination method that could work for areas with less access to resources and also could be adapted to mitigate the "Fit" concern for disposable PPE
I've been doing as much reading on this topic that I can find (Even called a microbiology PhD Ag friend and emailed the authors of this paper https://elautoclave.files.wordpress.com/2020/03/stanford-2020.pdf).
First, Its important to state that Dr. Price and Dr. Chu's paper's specifically mentions that they have not tested the efficacy of these methods against decontaminating against COVID-19. They have simply been testing the integrity of the meltdown material in the N95 masks.
As their paper states, "To be useful a decontamination method must eliminate the viral threat, be harmless to end users, and retain respirator integrity." The paper summarizes, "70C/158F heating in an oven for 30 min... is an effective decontamination method". In an updated paper they increased the temperature to 75C. I thought of a possible "low tech" solution that could be leveraged in situations where specialized equipment is unavailable (ex. vacuum ovens or Vaporous Hydrogen Peroxide (VHP) autoclaves).
My proposed solution consists of placing an N95 mask in a vessel (ex. ziploc bag) and immersing in a water bath set to 75C(or higher) for 30 min (or longer)? Home chefs use this method often for cooking sous vide (under vacuum) and holding food at a set temperature for extended periods of time. The lower the temperature, the longer you have to hold to kill bacteria and viruses.
I think this method should also be tested by materials scientists to measure the impact to the meltblown fibers. Perhaps this water bath method would cause less damage to respirator integrity due to the nature of a gentle thermal load. Additionally, perhaps masks could be held at a lower temperature for longer periods of time, decreasing the impact to meltdown, elastic, and nose padding.
The Vacuum oven method mentioned in the Stanford paper requires that masks be placed on a rack or flat surface. One of the additional concerns the CDC and The National Institute for Occupational Safety and Health (NIOSH) mentions is the fit of the masks after multiple decontamination cycles. [url=https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html][/url]https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html
Additional considerations to the water bath method: Molds could be developed to place masks over before sealing in "the vessel" and immersed, essentially maintaining (or resetting) the masks shape and therefore its fit.
Vaporous Hydrogen peroxide (VHP) enclaves are probably a better solution but they are going to take some time to be available in other areas in the nation let alone globally. In poorer countries, they wont even have that as an option.
This method needs to be tested for impact to the meltdown material, needs to be researched on its impact to COVID-19, and needs to be run by manufacturers to see if the "mold" consideration can assist with fit concerns.
I'm asking for anybody's thoughts here on Texags. If you know someone who is in materials research and can weigh in or possibly know someone who is connected to 3M engineering, let me know.