Photo Credit: Aparajhitha Sudarsan
By Katie Kroeze
A new mask decontamination technology developed by University of Guelph researchers can help to alleviate disposable mask shortages in health care during the COVID-19 pandemic, according to a new study.
Dr. Kevin Keener, an engineering professor in the College of Engineering and Physical Sciences, conducted the study with research scientist Dr. Vanessa de Souza and M.Sc. students Aparajhitha Sudarsan and Troy Kozlowski, as well as post-doctoral researcher Dr. Alba Illera and PhD candidate Nooshin Nikmaram.
They found that high-voltage atmospheric cold plasma (HVACP) treatment – a non-thermal technology for effective decontamination of foods – successfully cleaned surgical masks without causing structural or functional damage.
“In the context of a public health emergency, such as the COVID-19 pandemic, the supply of personal protective equipment is under severe strain,” says Keener. “To avoid shortages of this critical equipment, approaches such as re-sterilizing surgical masks after use is recommended.”
This research took place at the beginning of the COVID-19 pandemic, when increased demand for disposable masks outstripped their supply. Direct testing using the COVID-19 virus was unavailable at the time so the research team, using published literature, selected E. coli as a surrogate for the COVID-19-causing virus.
The research team tested four treatments on E. coli-inoculated masks. They found HVACP treatment worked faster than previously studied mask sterilization methods. Only one minute of treatment was required to sterilize the items, with 30 minutes of post-treatment hold time. Under these conditions, high concentrations of ozone, peroxides, and nitrates are produced to inactivate E. coli.
The technology solution, proven effective for the re-use of disposable masks, could also be implemented for decontamination of re-usable masks and other PPE with additional testing.
“In previous studies, low levels of ozone gas have been found to easily inactivate COVID-19; however, ozone gas alone can degrade mask performance such weakening elastic straps, so this is quite promising,” says Keener.
To examine mask integrity, the researchers performed gas permeability testing on the untreated disposable masks and masks put through five decontamination cycles. They found that treatment had no effect on either the pore diameter size (i.e., breathability) or tensile strength of the elastic straps on the masks.
The study’s findings could help reduce waste by providing a technology solution to easily decontaminate masks and other personal protective equipment (PPE) at hospitals and other facilities in a cost-effective manner.
“In the future, we would like to work on a larger treatment chamber to be able to sanitize a higher number of masks at once or other PPE,” says Keener. “This experiment would inform us of the practicality of using this decontamination method.”
This research study, while focused on the COVID-19 pandemic, has shown that cold plasma can be an affordable alternative to existing PPE sterilization technologies, such as steam and ethylene oxide, that are being used in hospitals and medical facilities.
This research was funded by the COVID-19 Research Development and Catalyst Fund and the Barrett Foundation in Sustainable Food Engineering.