According to findings published in the journal Environmental Science and Technology Letters, this could allow users to safely reuse limited supplies of respirators, originally intended to be single-use items.
N95 respiratory masks are the gold standard for personal protective equipment that protects the wearer against droplets and airborne particles, such as the coronavirus responsible for Covid-19.
“A cloth or surgical mask protects others from droplets the wearer might expel, but a respiratory mask protects the wearer by filtering out smaller particles that may carry the virus,” said Thanh Nguyen, professor at the University. from Illinois to Urbana-Champaign in the US.
Strong demand during the Covid-19 pandemic created severe shortages of healthcare providers and other essential workers, prompting a search for creative approaches to sanitation.
“There are many ways to sterilize something, but most will destroy the filtration or fit of an N95 respirator,” University of Illinois Professor Vishal Verma said.
“Any method of sanitation would require decontaminating all surfaces of the respirator, but it is equally important to maintain the efficiency of filtration and the fit of the respirator on the wearer’s face. Otherwise, it won’t offer the right protection, ”Verma said.
Researchers see the potential of the electric cooker method to be useful for healthcare workers and first responders, especially those in small clinics or hospitals that do not have access to large-scale thermal disinfection equipment .
It may be useful for others who may have an N95 respirator at home – for example, from a pre-pandemic home improvement project – and wish to reuse it, they said.
The researchers hypothesized that dry heat could be a method to meet all three criteria – decontamination, filtration, and adjustment – without requiring special preparation or leaving chemical residue.
They also wanted to find a method that would be widely available to people at home.
The team decided to test an electric cooker, a type of appliance that many people have in their pantries.
They verified that a cook cycle, which keeps the contents of the stove at around 100 degrees Celsius for 50 minutes, decontaminated masks, inside and out, of four different classes of viruses, including a coronavirus – and did it more effectively than ultraviolet. light.
“We built a chamber in my aerosol testing lab specifically to examine the filtration of N95 respirators, and measured the particles that pass through it,” Verma said.
“The respirators maintained their filtration capacity of over 95 percent and held their shape, still properly seated on the user’s face, even after 20 cycles of decontamination in the electric range,” he said. .
The researchers note that the heat should be dry heat – no water added to the stove, the temperature should be kept at 100 degrees Celsius for 50 minutes, and a small towel should cover the bottom of the stove to prevent any part of the stove. respirator in direct contact with the heating element.
However, multiple masks can be stacked to fit inside the stove at the same time, Nguyen added.