Faye Yap, left, and Zhen Liu, graduate students at Rice University, describe a sample of a mask. A framework for effectively decontaminating disposable facemasks has been devised by researchers from Rice and the University of Texas Medical Branch, Galveston.
More than 99.9% of the viruses they examined, including SARS-CoV-2, were found to be destroyed by heating a mask in a 160°F oven for five minutes. Credit: Rice University/Jeff Fitlow, Rice University Creates
The correct amount of heating PPE destroys 99.9% of the SARS-CoV-2 virus without deteriorating the material.
Here’s how to disinfect a disposable face mask: It should be heated in an oven for five minutes at 160 degrees Fahrenheit. Own oven is an option.
Engineers at Rice University have concluded that adequate heating will successfully eradicate the virus that causes COVID-19 from a common disposable surgical mask without causing the mask itself to degrade. They claim that the science now supports their findings.
Masks can be decontaminated and worn again before degrading, according to research by mechanical engineer Daniel Preston of Rice’s George R. Brown School of Engineering, graduate student Faye Yap, and associates at the University of Texas Medical Branch (UTMB), Galveston. Rice University Creates
The best part is that heating
to 70 degrees Celsius (about 160 F) killed almost 99.9% of SARS-CoV-2 and other viruses they tested, complying with FDA decontamination criteria. This indicates potential for modifying the strategy to manage epidemics in the future where personal protective equipment (PPE) is expensive.
Faye Yap, left, and Zhen Liu, graduate students at Rice University, describe a sample of a mask. A framework for effectively decontaminating disposable facemasks has been devised by researchers from Rice and the University of Texas Medical Branch, Galveston. VA Home Loans
More than 99.9% of the viruses they examined, including SARS-CoV-2, were found to be destroyed by heating a mask in a 160°F oven for five minutes. Credit: Rice University/Jeff Fitlow
The paper is the third,Rice University Creates
in a series that was motivated by the COVID-19 epidemic and funded by a Rapid Response Research grant from the National Science Foundation. In August 2020, the first study made the case for the viability of a thermal decontamination method. The second article,
which was published in May, evaluated how the virus fared in different parts of the United States depending on ambient temperature ranges. Rice University Creates
The current study introduces a modeling framework that scientists can use to calculate the precise amount of heat and duration needed to kill a certain virus. Preston emphasized that the framework is applicable to viruses that reside on surfaces and spread predominantly through touch in addition to airborne viruses like SARS-CoV-2.
Authors of the study Yap and Preston described existing decontamination techniques that have been tried but only partially effective: steam, which can compromise a mask’s structural integrity; exposure to ultraviolet light, which can leave harmful residues and may also degrade the material; or chemical disinfectants.
According to Preston, Rice University Creates
an assistant professor of mechanical engineering, ultraviolet radiation is generally quite successful, especially for flat or smooth surfaces. There is a lot of excellent work out there, but not everyone has access to UV light, and heat fixes any problems caused by cloth folds or fissures. Rice University Creates
Preston thought his lab was the best place for the project, along with collaborators in Galveston who handled the majority of the heating tests, after seeing that little had been done to develop a modeling framework for decontaminating PPE.
He remembered, “We actually couldn’t locate anything in the literature that discussed the effect of temperature on virus decontamination. “At the very least, nothing that could be used to combat the pandemic. Even before we submitted our grant application, that put us in this situation. VA Home Loans
The temperature inactivation of the virus,
he continued, “may be simply described by a combination of two fundamental relationships, which is ultimately what we postulated and have now proved to be correct.” The Arrhenius equation,
which connects the reaction parameters to temperature, is one of them. The rate law, on the other hand, employs those reaction parameters to determine how quickly a reaction takes place. The virus itself is rendered inactive in this situation.
The mask must be heated all the way through, according to Yap. Masks are thin, so that’s less of a problem than decontaminating bulkier materials, a subject the Preston lab will research in the future. Cloth masks should function just as well when heated to 70 C as long as all layers attain the necessary temperature for the full five minutes.
She pointed out that, as they could see in microscope photos of their samples, the polymer fibers that make up the majority of masks will melt if the heat is too high. The middle filter layer in the mask begins to deform at around 125 C, and it melts at 160 C, according to Yap. “There’s a narrow line when you start to go close to the melting point of the material.”
However, the decontamination technique does work quite well in those instances. You may still inactivate the viruses in five minutes, according to Yap, if you can get the entire mass to reach the necessary temperature, which is 70 degrees Celsius. Masks did not considerably degrade even after being heated to the appropriate temperature for up to 30 minutes, she claimed.
While Preston expressed hope that COVID-19
is receding in the West, she added that PPE shortages continue to be an issue in many regions of the world. Many people could benefit from a quick and efficient way to disinfect masks. However, reusing masks is not the only way to ensure your safety during a pandemic.
I don’t want to say that stopping the spread of COVID-19 by thermally inactivating viruses that have been stabilized on surfaces, he added. “Viruses will continue to be transmitted from person to person via aerosolized droplets. That can be avoided with masks, and disinfection is a supplementary measure to stop the spread.
Reference: Te Faye Yap, Jason C. Hsu, Zhen Liu, Kempaiah Rayavara, Vivian Tat, Chien-Te, K. Tseng, and Daniel J. Preston, “Efficacy and Self-Similarity of SARS-CoV-2 Thermal Decontamination,” Journal of Hazardous Materials, 7 November 2021. DOI: 10.1016/j.jhazmat.2021.127709