New face mask study: Three layers best, but every layer helps
Australian research shows how different mask types stop the spread of droplets.
A new medical research study suggests that three-layer masks are the most effective in helping contain the spread of coronavirus, but highlights that even simple homemade masks can be useful.
The research was conducted by a team of academics from the University of New South Wales. It was published in the British Medical Journal title Thorax for early access and discussion, but hasn't yet been peer reviewed.
The researchers used video imaging to track the impact of three different types of masks on the spread of droplets produced when speaking, sneezing and coughing:
- Three-layer surgical masks, as used by medical professionals
- Two-layer homemade masks made using a method recommended by the US Centers for Disease Control (CDC)
- A "no-sew mask" made from a single sheet of cloth
The study confirmed that more layers confined the spread of droplets better, but noted that even a basic mask did help limit spread:
For speaking, a single-layer cloth face covering reduced the droplet spread but a double-layer covering performed better. Even a single-layer face covering is better than no face covering. However, a double-layer cloth face covering was significantly better at reducing the droplet spread caused by coughing and sneezing. A surgical mask was the best among all the tested scenarios in preventing droplet spread from any respiratory emission.”
The study also noted that mask type alone isn't the sole determinant of efficiency. Materials used, the arrangement of layers and frequency of washing can all have an impact. It recommends multiple layers in homemade masks when that's feasible.
That echoes current advice from doctors. "Reusable masks with 3 layers hit the Goldilocks zone, providing adequate protection while still allowing you to easily breathe," Dr Brad McKay told Finder last week.
Demand for face masks in Australia has shot up dramatically after Victoria introduced mandatory mask wearing in Melbourne and Mitchell Shire last week. Suppliers say that there should be plenty of supplies available, but there's concern that a rush on masks could emulate earlier issues with supply of toilet paper and other essentials.
Want more help with masks? Check out our overview of face masks, how to choose the best one, what doctors recommend when using them, the rules that apply in Australia and our regularly-updated guide on where to buy reusable masks.
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