The use of air purifiers in schools has been a key sticking point in tensions between the Education Department and the SA teachers’ union, with the State Government claiming the filters are unnecessary despite Victoria, New South Wales, Tasmania and Western Australia all deploying them in classrooms to prevent the spread of COVID-19.

In a press release earlier this month, the department said it commissioned an independent trial that found air purifiers “do not reduce the amount of CO2 within education spaces in any meaningful way and provide minimal improvement to the quality of the air”.

It said it had decided “not to deploy air purifiers to every classroom, staff room and learning space across the state” in accordance with the findings and advice from SA Health, and would instead ensure classrooms had better access to natural ventilation.

But the department revealed this week it had now purchased more than 4000 purifiers.

A local supplier and manufacturer of room air purification systems questioned the department’s initial advice, saying air purifiers are not designed to get rid of carbon dioxide.

Holyoake SA general manager Nick Braithwaite, who is based at Torrensville, said he tried contacting the department and several school principals asking if they were interested in purchasing his products, which retail for $3500.

If such a study was done, that is a news story in itself

He said he recently supplied the Women’s and Children’s Hospital with about 30 air purifiers and it was “naïve” of the Education Department to suggest they were ineffective.

“They (the department) told me the study they did was looking at the carbon dioxide levels, but one thing has got nothing to do with the other,” he told InDaily. 

“In the main, it’s very hard to reduce carbon dioxide levels if you think about it – you could put some plants in there – but all it is really is an indication of how many people are in a room.

“If you do a bit of research on Google, you’ll see it’s very hard to change the makeup of air, as in how much nitrogen, how much oxygen, how much carbon dioxide is in the air in a small environment.

“It’s not an indication of airborne pathogens – and COVID-19 is an airborne pathogen.”

Braithwaite said air purifiers were effective tools for dragging aerosol particles such as COVID-19 from the air and he suspected the decision not to purchase them was driven by financial constraints.

“A room air purifier scrubs the air, it gets rid of airborne pathogens such as COVID-19, such as the common cold,” he said.

“Basically, you end up with air inside that’s cleaner than the air outside and that’s not a gimmick – that’s exactly what they do.”

Medical experts and scientists have also questioned why the Education Department measured carbon dioxide levels to determine whether air purifiers are effective tools for mitigating the spread of COVID-19.

To confuse ventilation with filtration, which removes particles but not CO2, is quite a face-palm error

Sydney paediatrician and ICU specialist Dr Greg Kelly said the department had a “dangerous misunderstanding of (the) role of HEPA air purifiers in reducing COVID-19 transmission”.

“Measuring CO2 is a marker ONLY of ventilation,” he tweeted.

“Imagine dirt in water. We can either rinse it away (ventilation), or filter it.

“To continue the dirty water analogy – the press release is saying that we filtered the water but it was still wet afterwards, therefore the filter doesn’t work. But the filter is designed only to pull out the dirt, NOT to dilute what’s in the water which is what the CO2 measures.

“If such a study was done, that is a news story in itself as it reveals such fundamental misunderstanding.”

Hi @edu_sagov @SAHealth -this press release contains dangerous misunderstanding of role of HEPA air purifiers in reducing #COVID19 transmission

Purifiers DO NOT remove CO2, so this trial says nothing about their ability to remove virus, which they can dohttps://t.co/2kieMgwY7J pic.twitter.com/jrpRkqCJat

— Dr Greg Kelly (@drgregkelly) January 27, 2022

Australian National University Research School of Physics and Engineering Professor Ben Buchler added: “to confuse ventilation with filtration, which removes particles but not CO2, is quite a face-palm error”.

“I guess it’s possible that measurements of air within purifiers showed no meaningful improvement in air quality with respect to aerosol particles, but that is definitely not what this page says,” he tweeted.

The Education Department told InDaily that it accepted that its statement “may have given the incorrect impression that our trial assessed CO2 levels, rather than particle concentration”.

“We would like to clarify that the point we were trying to make was that increased air-flow through ventilation is among the most effective ways of reducing risk, echoing the advice from SA Health that air purifiers are not a means of increasing air flow,” a department spokesperson said.

The spokesperson did not say who it commissioned to conduct the independent trial.

InDaily also sent several questions to SA Health. In response, a spokesperson sent a link to a fact sheet, which stated: “where airflow cannot be improved, air purifiers with HEPA filters (high efficiency particulate air filter) could be considered. However, air purifiers with HEPA filters have not yet been demonstrated to prevent disease in an experimental situation.”

The Education Department’s chief executive Rick Persse told the Australian Education Union yesterday that his staff had purchased a total of 4050 air purifiers for classrooms.

Asked why the department purchased the purifiers given its previous claims, a spokesperson said they would be used for “circumstances where natural ventilation or air quality is impacted by outside environmental conditions, such as in the instance of a bushfire”.

“We have 4,000 units, some of which we’ve already sent to schools, preschools and children’s centres in Port Pirie,” the spokesperson said.

The department said it would “continue working with our education sites across the state to safely maximise the natural air ventilation in classrooms, which is the recommendation of SA Health, and will ensure we have adequate supply of air purifiers to quickly deploy where they are needed”. 

InDaily asked the department how much the air purifiers cost, but is yet to receive a response.

It comes as the Australian Education Union re-ballots teachers to find out if they support postponing strike action next Wednesday.

Teachers have until 5pm tonight to vote on whether to postpone the strike “until further notice”, with the outcome to determine whether the school year will begin as scheduled on February 2.

Almost two-thirds of teachers who responded to a ballot on Monday voted to strike, but AEU officials yesterday afternoon agreed the government had made sufficient progress meeting their demands.

Union members want regular surveillance testing of students and teachers, but the government argues that would provide a false sense of comfort and is only necessary in preschools and early learning centres where staff come in close contact with children.

However, in advice to the national cabinet in November, the Doherty Institute recommended twice-weekly screening of students to reduce the number of exposure days in school.

“Regular screening of students in schools at risk of COVID-19 incursions can result in fewer infections and in-person teaching days lost,” the advice stated.

“The more frequent the screening the greater the benefits.”

Shadow Health Minister Chris Picton said the Doherty Institute had provided “clear advice” that rapid antigen testing should be used frequently in schools.

“Doherty said clearly that twice weekly RATs for students reduces outbreaks and transmission in the community – so why is South Australia bucking that advice?,” he said.

Premier Steven Marshall said yesterday that because rapid antigen tests were a “point in time test” they were “highly inaccurate in terms of false negatives”.