Surgical masks are loose, single-use fabric masks intended to shield the body or other dangerous fluids from large droplets, splashes, or sprays. As the user inhales, these types of masks suffer leakage around the edges and do not have a reliable respiratory degree of protection against smaller airborne particles.
These masks are commonly regarded as single-use disposable products in professional healthcare settings. We find no existing literature on the decontamination processes of used surgical face masks as of this writing. Since they are not designed to protect the consumer against the spread of airborne diseases and are inexpensive enough to be treated as single-use disposable products, it is likely that no research on their decontamination for reuse has been conducted.
Decontaminate of surgical mask:
The intense competition for personal protective equipment during the novel outbreak of coronavirus has prompted the need to implement supply conservation strategies. To allow for surgical mask reuse, little is known about decontamination interventions.
The aim is to define and synthesize original research data to test strategies to decontaminate surgical masks for reuse purposes.
The method used to kill pathogens and decontaminate masks while maintaining their filtering ability, we optimized the temperature used in the dry heat pasteurization process.
The present study shows that dry heat could successfully kill 6 species of respiratory bacteria and one species of fungi for 1 hour at both 60 ° C and 70 ° C, and inactivate the H1N1 indicator virus. The N95 respirators and surgical face masks showed no improvements in their shape and components after being heated at 70 ° C for 1, 2, and 3 hours.
For N95 respirators, the filtering efficiency of bacterial aerosol was 98 percent, 98 percent, and 97 percent after heating for 1, 2, and 3 hours, respectively, all of which were over the 95 percent efficiency needed and comparable to the value before heating (99 percent). The filtering efficiency for surgical face masks for 1, 2, and 3 hours of heating was 97 percent, 97 percent, and 96 percent, respectively, all of which were also close to the value before heating (97 percent).
Decontamination interventions for Surgical masks:
For prospective original research on decontamination interventions for surgical masks, MEDLINE, Embase, CENTRAL, Global Health, the WHO COVID-19 database, Google Scholar, Disaster Lit, preprint servers, and prominent journals were searched from initiation to April 8, 2020.
Citation screening was carried out in duplicate, separately. Two independent reviewers extracted research attributes, interventions, and conclusions from the included studies. Outcomes of concern included the impact on surgical mask efficiency and germicidal effects of decontamination measures.
Seven studies met eligibility criteria: one measured the impact on mask performance of heat and chemical interventions applied after mask use, and six examined interventions applied to improve antimicrobial properties and/or mask performance prior to mask use. With heterogeneous test conditions, mask efficiency and germicidal effects were assessed. Protection results were seldom measured.
There is little evidence that surgical mask decontamination is safe or successful. We are unable to draw conclusions on the most successful and safe intervention for decontaminating surgical masks, given the heterogeneous methods used in studies to date.
Methods of decontamination:
Hydrogen Peroxide Vapor (HPV):
As an industrial decontaminant, hydrogen peroxide vapor has long been used, and recent studies by the Dutch National Institute of Health have shown that this approach is effective in inactivating similar viruses and does not affect N95 masks.
The Duke University facility provides a Bioquelltm Clarustm C system with a hydrogen peroxide solution and a delivery system of 35 percent concentration that is used in the decontamination room to reach a uniform concentration of 480ppm+ throughout the decontamination room.
A 10-minute conditioning process, 30-40 min gassing phase at 16 g / min, 25 min dwell phase, and 150 min aeration phase were included in the HPV cycle (15). In the center of the decontamination chamber, 100 N95 masks were hanging from a metal rack while the cycle was working.
Heat & Moisture:
There is a growing body of evidence supporting potential SARS-CoV-2 viral inactivation through the use of heat, relative humidity, and time.
Research carried out at standard 121C sterilization temperatures with autoclaving masks showed inconsistent results. One study (9) showed that a specific mask could be processed up to five times without loss of filtration performance or fit.
Viral inactivation studies were not conducted because tests with commonly accepted parameters for steam sterilization were conducted. However, when tests were performed on different masks under similar parameters (8), the results showed unacceptable physical deformation preventing proper fit as well as philter efficiency degradation below acceptable limits.
Microwave Generated Steam (MGS):
As shown, perforated plastic reservoirs are filled at room temperature with about 50 mL of tap water, the contaminated N95 mask is placed on top of the center of the assembly and loaded into a commercially available microwave oven and exposed to radiation for two minutes (one minute on each side of the mask)
The use of this technique resulted in an average log reduction of viable viruses of 5.06. Notice that many N95 mask designs feature metallic nosebands that will melt the surrounding area of the mask when exposed to microwave radiation, making it unusable (12). However, for masks subjected to this method of disinfection that did not contain any metallic components, average aerosol penetration and airflow resistance were not shown to have significantly changed.