The COVID-19 caused by the extreme acute respiratory syndrome coronavirus is gripping the world. Health care professionals and those who care for these patients are at serious risk of having the infection. In order to prevent the spread of the infection through aerosols produced when coughing, sneezing, or even breathing, N95 masks have been listed as protective face gear to cover the face, nose, and mouth of the patient.
N95 facial masks have been in short supply since the onset of the COVID-19 pandemic. But because of the shortage, many have to wear the same mask repeatedly. Now, ACS Nano researchers have tested multiple techniques for disinfecting N95 products, finding that heating them retains their filtration ability for 50 disinfection cycles.
About The Study
The researchers write that there is a severe shortage of N95 respirators, and their study aimed to “determine how in these urgent times, we can reuse respirators and other personal protective equipment.” They clarified that there is a fiber layer called “melt-blown polypropylene fibers” in these N95 masks.
These form a breathable fabric that the wearer can breathe through. To filter out and protect the wearer from smaller particles like viruses, they explained these fibers are electrostatically charged.
Recommendations For Use And Disinfection
The Centers for Disease Control and Prevention (CDC) advises that the N95 filtering facepiece respirators (FFR)’ should be part of the health care staff’s Personal Protective Equipment (PPE) to avoid inhalation and exposure to viral aerosols during the COVID-19 pandemic.
This grade is calculated by the National Institute of Occupational Safety and Health ( NIOSH) of the CDC (document 42 CFR Section 84), as stated by the authors. For “0.3 μm (aerodynamic mass mean diameter) of sodium chloride aerosols, this mask, they stated, has a minimum filtration capacity of 95 percent.”
Healthcare workers are forced to reuse these masks because of the shortage. Several methods may be used to clean these masks, according to the CDC. Several of these are;
- Denaturation of proteins by alcohol or heating
- Genetic material disruption-DNA or RNA with Ultraviolet ( UV ) light, peroxides, or oxidizers
- Cell body destruction using phenolics, chlorides, and aldehydes
What Was Done?
These five techniques that could be used for the disinfection and reuse of N95 masks were compared by Yi Cui and colleagues in this report. They wanted to see if the fabric of the masks held up after continuous disinfection using one of these methods and was as successful as before. They examined whether it was capable of filtering the aerosol particles that appeared as respiratory droplets but lacked the novel coronavirus after subjecting a piece of the fabric to the disinfection process. Before and after the disinfection, they compared the fabric’s capacity to flush out the aerosols.
Heating As a Disinfection Method
The results showed that heating at 70 ° C for up to 5 minutes was one of the most effective and user-friendly disinfection methods. The team wrote that it was very productive if the melt-blown fabrics and the N95 masks were heated to less than or equal to 85 ° C at less than 100 percent relative humidity. They wrote that “the most promising, non-destructive approach for maintaining filtration properties” was this approach.
Ultraviolet (UV) Irradiation As a Disinfection Method
The researchers found that Ultraviolet (UV) Irradiation is an alternative to heating. Up to 10 cycles of such irradiation could withstand the masks and the fabrics. There was a “tiny deterioration” of the fabric after around 20 cycles, they noted. They noticed that the sealing and the material strength of the masks could be compromised by UV radiation. However, the dose of UV radiation that could disinfect the masks effectively was not clear.
Other Methods
The researchers wrote that the use of steam, household bleach, and aerosols could lead to degradation of the filtration ability of the masks and thus leave the “consumer susceptible to viral aerosols.” The filtration capability dropped from 96 percent to 56 percent (for alcohol spray) and 73 percent (for bleach spray) if alcohol or chlorine bleach solution was sprayed on the masks.
Conclusion
The team concluded that it is important to find ways to safely clean and reuse the N95 respirators because of the acute scarcity. They warn that the disinfected masks’ ability to flush out the coronavirus was not checked in their study, but results showed that heating remained one of the best methods of disinfecting these masks.
Alcohol solutions, chlorine-based solutions, or soaps for cleaning the respirator “are also recommended as these will alter the electrostatic charge inside the fabric that helps to filtrate the viral aerosols.”
Thankfully, many manufacturers of N95 masks are producing more and more supplies to aid the scarcity of these protective masks. To look for N95 masks for sale, click here.
