How a nebuliser can give coronavirus millions more droplets to 'hitch a ride on'
A guest in Melbourne's hotel quarantine system was positive with COVID-19 when they used a nebuliser, believe experts, who say every second they used the machine they would have been releasing up to 10,000 times more aerosol particles than if they were breathing normally.
And that would have given SARS CoV2 — the virus that causes COVID-19 — millions more droplets to "hitch a ride" on.
According to senior lecturer in mechanical and aerospace engineering at Monash University Daniel Duke, a nebuliser does not make the virus more potent, travel further or hang around in the air longer.
"There is simply more opportunity for the virus to be transmitted by aerosol," he said.
The use of the device is being investigated by Victorian Health Authorities, with the number of cases linked to the Melbourne Holiday Inn outbreak now at eight.
Victoria's Chief Health Officer Brett Sutton said at least three of those were believed to be linked to the use of the nebuliser.
Experts say it is a step forward that health authorities are acknowledging the aerosol spread of SARS CoV2 — the virus that causes COVID-19 — but insist more needs to be done to protect those working among it.
A nebuliser is a medical device designed to vaporise medication for users to inhale, sending a concentrated dose straight to their lungs.
Someone using a nebuliser attaches a mask to their face and breathes in and out, but a device can become contaminated if the user is shedding a virus at the time.
Dr Duke said the whole point of a nebuliser was to deliver as many aerosol droplets to the lungs as possible.
"The problem with nebulisers is that they ... are purposefully designed to produce thousands of times more aerosol than natural breathing," he said.
"When someone inhales a nebuliser mist, it goes into their lungs and then they breathe a lot of it back out again.
"A substantial portion of that aerosol has been in contact with the person's upper airway."If the person is shedding a lot of virus, there is likely to be a high chance a lot of those virus particles will hitch a ride on those aerosol droplets."
Dr Duke said the whole point of a nebuliser was to deliver as many aerosol droplets to the lungs as possible.
"The problem with nebulisers is that they ... are purposefully designed to produce thousands of times more aerosol than natural breathing," he said.
"When someone inhales a nebuliser mist, it goes into their lungs and then they breathe a lot of it back out again.
"A substantial portion of that aerosol has been in contact with the person's upper airway.
https://www.abc.net.au/news/2021-02-11/how-a-nebuliser-produces-droplets-covid-19-can-hitch-a-ride-on/13140554
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