Early on in the COVID-19 outbreak, Melbourne ophthalmologist Associate Professor Ehud Zamir was not alone in his concern for dwindling mask stocks.
He had previously used the common surgical fabric Halyard Sterilization Wrap for domestic purposes, prompting him to consider its potential as a basis material for masks.
“The material was designed and proven to be permeable to gas/air while providing a barrier against bacteria and liquids. It’s used in large quantities in every operating theatre and is usually discarded after unwrapping the surgical packs,” he says.
Zamir conducted some encouraging preliminary testing. Then his daughter, Ms Maya Zamir, a veterinary student, stumbled upon Dr Bruce Spiess, a Professor of Anesthesiology at the University of Florida, who had already published a method of producing masks with the same fabric.
Using Spiess’s approach, Maya Zamir formed a volunteer group that is sewing masks for Victorian health professionals, using Halyard material gathered from Melbourne hospitals. More than 400 free masks have now been supplied to ophthalmologists, GPs, anaesthetists and theatre nurses, among other allied health professionals.
While correctly fit P2/N95 masks remain the gold standard, Zamir notes their availability can be limited and highly regulated for those in intensive care units (ICU).
He cautions his hand-made masks haven’t been tested or proven effective. However, he says they probably offer greater protection than a standard surgical mask.
“With masks there are two main parameters; the first is how well it filters and the second is how well it seals. Without a good seal, no mask will protect the wearer, regardless of material. The great thing about our masks is that it sits tightly on your face. It seals well, you can see it breathing in and out. It also blocks various odours, including perfumes, which to me proves that it is an effective filter,” he says.
The mask has been tested and has apparently performed well in qualitative fit tests.
“The filtration ability probably isn’t as high as an N95, but N95 respirators are designed to meet a very high filtration standard, not necessarily representative of clinical exposure. For most of us who don’t work in an ICU, where there are presumably large quantities of virus-containing aerosols, I think the Halyard/ Florida mask will provide some protection, especially if your patients also wear masks.”
In terms of reusability, Halyard masks are made of a material designed to go through the autoclave.
For decontamination and reuse, they can be put in 70C dry heat for 60 minutes, as per the US National Institutes of Health paper on N95 decontamination.
Other methods include hydrogen peroxide mist before hanging to dry, or dipping the mask for 30 seconds in five parts water to one part bleach prior to hanging to dry.