A teacher on Queensland's Sunshine Coast is questioning how effective the mask mandate will be when school starts next week, arguing students would not be wearing them most of the time.
Air quality experts have also called for more effective masks, respirators, to be worn, warning coronavirus was "potentially very transmissible" in a classroom setting.
Under the Queensland government's back-to-school plan, high school students and teachers must wear a mask unless they are seated or are able to maintain a 1.5 metres distance from others.
Carmel Walton, a secondary school teacher in Noosaville, said the mask protocol "seems completely pointless".
"As any teacher knows, the students are seated for the majority of the time in the classroom … so there's no mandatory masks happening at all," Ms Walton said.
"Then they're also saying the teacher doesn't have to wear a mask while they're teaching, which is the whole time inside the classroom as well — so I don't see when they think they're going to wear them."
Due to safety concerns, Ms Walton has decided not to teach at the start of the year and has a contingency plan for her two high school children.
"The youngest is starting year 7 and it's really important for her to be socialising," Ms Walton said.
"If cases start appearing, and of course they're going to spread very quickly if none of them are wearing masks, then we will keep them at home."
Ms Walton said it would have "reassured" her if students and teachers were expected to always wear face masks in school.
"Because of my science background, my children know what to do and all the risks, so they will probably wear a mask in class despite not having to," Ms Walton said.
"But for a teenager, that can be quite hard when all their peers aren't wearing them."
She is also concerned her 14-year-old is not eligible for the booster, despite receiving her second vaccination four months ago.
If her children get infected, Ms Walton said she is worried they will infect their 84-year-old grandmother and 87-year-old grandfather.
'Classrooms potentially 'very transmissible'
QUT's International Laboratory for Air Quality and Health director Lidia Morawska said COVID is "potentially very transmissible" in a classroom setting.
"We are talking about a group of people — let's say, 20 to 30 kids in a classroom," Professor Morawska said.
"So this creates situations in which the transmissibility of the virals will be quite high."
As COVID is an airborne disease, Professor Morawska said she "can't quite understand" why the government's back-to-school plan allows teachers to remove their masks to teach, and children to remove them when they are seated.
"[Transmission has] nothing to do with whether people are sitting or standing, or walking for that matter, it has to do with recovery activities," she said.
Professor Morawska said acts of vocalisation like talking and singing increases the risk of transmission because of aerosol emissions.
Aerosols are small particles that contain the COVID-19 virus and linger in the air "like cigarette smoke" when people breathe out.
"You could be sitting and singing, and [aerosol] emissions would be quite high," Professor Morawska said.
"Sitting and breathing, if the kids are close to each other, also creates a problem.
"I cannot quite understand why younger children wouldn't be required to wear masks."
Professor Morawska is an executive member of OzSage, a network of independent Australian experts established in the wake of the pandemic, which recommends all children in school wear respirators instead of cloth or surgical masks.
Respirators are masks that are sealed around the face and filter out small particles, like those found in bushfire smoke.
"Cloth and surgical masks are leaky so they don't offer as good protection as an N95/P2 respirator, which are specifically designed to protect us from airborne hazards," OzSage said in a statement.
OzSage said the fit of the mask is important so appropriately sized respirators such as child-size KF94 respirators should be used.
Air purifiers to be supplied if needed
In addition to using high-quality masks, Professor Morawska said another "very important" preventative measure in schools should be ventilation.
Professor Morawska explained, "ventilation is removing the virals from the air and ensuring that the ventilation is as good as possible".
She said carbon dioxide monitors could be used to assess whether the classroom or building was well-ventilated.
"Sometimes we can open a window, or adjust some settings, and we assume that perhaps the ventilation is fine, but unless we check it, we don't know this."
The Queensland government said schools would have access to these measuring devices and, "after considering all actions to improve ventilation, if it is deemed necessary, the department will provide portable air purifiers".
Education Minister Grace Grace said the government had refined its ventilation plan in consultation with a committee of government and non-government entities like QUT, the Doherty Institute and Safe Work Australia.
"We are nearly there with every single classroom in this state being air-conditioned or having manual ventilation of some sort but air conditioning is almost there and there's more to say about that very soon," Ms Grace said.
Chief Health Officer John Gerrard said children are unlikely to experience severe COVID symptoms.
"Obviously, there'll be infections among children but we don't expect many hospitalisations from that," Dr Gerrard said.
"The bigger risk from the schools opening is the parents and grandparents being infected from a child. That is the bigger risk. So it is critically important that the parents get vaccinated and the grandparents get that booster."
Dr Gerrard said they expect the overall numbers of COVID-19 cases to decline in aggregate across Queensland over the next week.
"The exact impact of schools is not clear," he said.
