Researchers Find Out Humidity and Heat Together Can Disinfect N95 Masks and Make them Reusable

Researchers Find Out Humidity and Heat Together Can Disinfect N95 Masks and Make them Reusable

Experts have already stressed on the importance of N95 masks for the frontline workers especially the medical staff that treat the Covid-19 patients. However, the shortage of these masks has forced them to reuse the N95 masks despite the fact that they are meant for single use only. Reusing the gear increases the risk of spreading coronavirus.

A group of researchers at the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University, and the University of Texas Medical Branch seem to have come up with an easy way to disinfect the used N95 masks, making them wearable for multiple occasions. This also helps in addressing the issue of shortage of N95 masks.

The newly found research says that the N95 masks can be disinfected used high relative humidity, which inactivates the SARS-CoV-2 virus trapped in them without hampering its performance.

One of the senior authors of this paper, Steven Chu said that if the masks can be recycled about a dozen times then the shortage problem can go down significantly.

Every health practitioner can possess up to a dozen masks. With the facility to decontaminate many N95 masks while they are on a tea break will bring down the chances of masks already contaminated with the coronavirus from being exposed to other patients, Chu added.

In this latest research, Steven Chu along with professors Wah Chiu and Yi Cui from Stanford and University of Texas Medical Branch virologist Scott Weaver, worked on decontaminating the N95 masks using the combination of heat and humidity.

The team worked in a biosafety measure equipped environment at the World Reference Center for Emerging Viruses and Arboviruses. They began with mixing batches of SARS-CoV-2 virus in different liquids that are designed to impersonate the fluids that may spray out of the mouths when we sneeze, cough, breathe, or sing.

Droplets of these different mixtures were sprayed on a piece of melt-blown fabric which is mostly used in the manufacturing of N95 masks. The droplets were left to dry on the fabric after which these samples were heated at various temperatures that ranged from 25 °C to 95 °C with 100% relative humidity for 30 minutes.

High humidity and heat significantly reduced the amount of virus present on mask. The team ensured that they did not increase the heat too much because the researchers, after performing some more tests, found that it lowered the ability of the fabric to filter the coronavirus droplets.

The exact amount of heat they figured out was 85 °C, along with 100% relative humidity. After the masks were put through these conditions, they found no traces of SARS-CoV-2 in them.

A few more results from tests revealed that the masks can be made reusable after decontaminating them for atleast 20 times. Besides the SARS-CoV-2 virus the similar process works on two other viruses – chikungunya virus and a common cold causing human coronavirus.

UT Medical Branch Weaver said that the results revealed are not astonishing because the researchers have long been aware of the fact that humidity and heat can inactivate viruses. However, previously there was never a crucial situation encountered which required a quantitative analysis of something like decontamination of masks. The data he added, would offer quantitative guidance for the future.

Cui said that even when the pandemic was over, this research would prove beneficial because the method can be utilized for other viruses too. Moreover, reusing masks is beneficial for the environment and cost-effective too.

The result of this research was published in the ACS Nano journal on September 25, 2020. It was supported by the DOE Office of Science through the National Virtual Biotechnology Laboratory and was funded by the Coronavirus CARES Act and by the World Reference Center for Emerging Viruses and Arboviruses, funded by the National Institutes of Health.

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