Fabric masks can filter out at least half of airborne coronavirus particles. Photo / Getty Images
Fabric masks can filter out at least half of airborne coronavirus particles. Photo / Getty Images
Throughout the Covid-19 pandemic, Kiwis have been encouraged to wear masks in public, as they're still compulsory on public transport in Auckland.
But if you're wearing home-made masks, how do you know they're working?
Researchers at Australia's Flinders University tested commonly available fabric masks and discovered that even the worst performing ones filtered at least half of airborne virus particles.
The study looked at the viral filtration efficiency (VFE) of a number of masks either bought off the internet or made at home.
Researchers challenged the masks by using a standard mask testing method with a model virus, called MS2, which is smaller in size than Covid-19.
Flinders University scientist Dr Harriet Whiley said while a 50 per cent reduction may not seem particularly effective, modelling studies suggested if 80 per cent of the population wore those masks in high transmission areas, the number of Covid-19 deaths in Australia could fall between 17 and 45 per cent.
"This would be even more improved in areas that you have lower transmission rates," she said.
"The information will also inform best practice for fabric face mask design to protect against respiratory diseases and reduce community-based transmission of SARS-CoV-2 (the virus that causes Covid-19)."
The VFE was calculated for two sizes of aerosols – being 6 microns, which is the size of aerosols produced by coughing, and 2.6 microns, which is small enough to be inhaled into the lower respiratory system.
The best performing masks filtered 97 to 99 per cent of the virus numbers.
FACEMASK
One mask, made with two layers of a shopping bag and one cotton layer according to Victoria's health department standards, reduced viral particles by 98.6 per cent.
Another, which had a filtration level of 55 per cent on its own, increased to 98 per cent when a dried baby wipe was inserted.
The VFE improved further after adding a section of a vacuum cleaner bag to 99 per cent.
Co-author Associate Professor Kirstin Ross said further research was needed to test mask design and fitting.
"Fit is very important to reduce the risk of viruses entering through gaps between your face and the mask," she said.
"There also should be an education campaign to inform people about how to wear fabric masks."
Dr Ross added it was important masks were worn correctly and should not be touched unless taking them off.
"Wash your mask after use in water that is hotter than 60°C with soap or laundry detergent," he said.
