But emergency doctor Carl Le said he had repeatedly encountered paramedics delivering patients to hospital while wearing vented masks.
“I’m sort of dumbfounded by what I’m seeing,” he said. “There is a risk of cross-contamination.”
Dr Le said he had personally raised the issue with paramedics.
“They just said, ‘This is what we’re supplied with’.”
When The Age asked Ambulance Victoria about the masks on Tuesday, the organisation said it was moving to non-vented masks “out of an abundance of caution”, with supplies arriving on Wednesday.
“The N95 vented masks are manufactured to Australian standards and provide high levels of protection. They were approved by the Department of Health and Human Services as part of pandemic planning,” a spokeswoman said on Wednesday.
“However, the guidelines around masks continue to evolve as new evidence emerges, so out of an abundance of caution, Ambulance Victoria is transitioning to non-vented N95 masks, with deliveries of stock taking place from today.”
Nine Ambulance Victoria paramedics have so far tested positive to COVID-19.
Australian Medical Association Victoria president Julian Rait said the paramedic mask situation was “another example of inconsistent advice” from the DHHS.
“That is not right for healthcare workers,” he said. “It’s just bizarre.”
Victorian Ambulance Union secretary Danny Hill said it was his understanding the masks were provided to paramedics by Ambulance Victoria. The masks are used when dealing with patients with COVID-19.
“It’s concerning that it’s come to the point where a doctor at a hospital has made a complaint before this issue has been detected,” he said.
On July 10, the official YouTube account of the DHHS uploaded a video of Chief Health Officer Brett Sutton saying valved masks should not be used.
“Make sure that your mask does not have holes or a valve. This can result in breathing out the virus if you have coronavirus,” he said.
On Saturday, Professor Sutton reiterated the advice.
“[A mask with a valve] allows the wearer to breathe out more easily and stops moisture build-up, but the problem is that it allows you to breathe out virus if you’re infected,” he wrote on Twitter.
“So although it might protect you, it won’t properly protect others if you are infected. So please, no valves on masks for COVID-19.”
N95 vented masks are typically sold to construction workers handling hazardous materials. They offer high protection to the user, effectively filtering out paint fumes and asbestos.
But masks worn during COVID-19 have a double purpose: to protect the wearer from the illness and to stop the wearer spreading the virus if they are infected. This is particularly important for people who have the virus but are asymptomatic.
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Healthcare workers use N95 masks without vents for infection protection.
An Ambulance Victoria spokeswoman said paramedics were temperature-checked before every shift. They also did not attend work if they had any flu or COVID-like symptoms or were otherwise unwell.
Liam is The Age and Sydney Morning Herald’s science reporter