Chennai: A research has concluded that N95 respirators, originally intended for one-time-use, could be reused after 50 minutes of dry heat in an electric cooker, such as a rice cooker or instant pot.
The University of Illinois, Urbana-Champaign study decontaminated N95 respirators inside and out while maintaining their filtration and fit.
N95 respirator masks are the gold standard of personal protective equipment that protect the wearer against airborne droplets and particles, such as the coronavirus that causes Covid-19.
Led by civil and environmental engineering professors Thanh ‘Helen’ Nguyen and Vishal Verma, the researchers published their findings in the journal Environmental Science and Technology Letters.
According to Nguyen, “a cloth mask or surgical mask protects others from droplets the wearer might expel, but a respirator mask protects the wearer by filtering out smaller particles that might carry the virus.”
High demand during the Covid-19 pandemic has created severe shortages for health care providers and other essential workers, prompting a search for creative approaches to sanitisation.
“There are many different ways to sterilise something, but most of them will destroy the filtration or the fit of an N95 respirator,” Verma said and added: “Any sanitation method would need to decontaminate all surfaces of the respirator, but equally important is maintaining the filtration efficacy and the fit of the respirator to the face of the wearer. Otherwise, it will not offer the right protection.”
The scientists hypothesised that dry heat might be a method to meet all three criteria—decontamination, filtration and fit — without requiring special preparation or leaving any chemical residue. They also wanted to find a method that would be widely accessible for people at home. They decided to test an electric cooker, a type of device many people have in their pantries.
They verified that one cooking cycle, which maintains the contents of the cooker at around 100 degrees Celsius or 212 Fahrenheit for 50 minutes, decontaminated the masks, inside and out, from four different classes of virus, including a coronavirus — and did so more effectively than ultraviolet light. Then, they tested the filtration and fit.
Verma said, “We built a chamber in my aerosol-testing lab specifically to look at the filtration of the N95 respirators, and measured particles going through it. The respirators maintained their filtration capacity of more than 95 percent and kept their fit, still properly seated on the wearer’s face, even after 20 cycles of decontamination in the electric cooker.”